diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index ad417c4c8d8..51cf38e5f41 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -5922,10 +5922,74 @@ module ts {
             return unknownSignature;
         }
 
+        // Re-order candidate signatures into the result array. Assumes the result array to be empty.
+        // The candidate list orders groups in reverse, but within a group signatures are kept in declaration order
+        // A nit here is that we reorder only signatures that belong to the same symbol,
+        // so order how inherited signatures are processed is still preserved.
+        // interface A { (x: string): void }
+        // interface B extends A { (x: 'foo'): string }
+        // var b: B;
+        // b('foo') // <- here overloads should be processed as [(x:'foo'): string, (x: string): void]
+        function reorderCandidates(signatures: Signature[], result: Signature[]): void {
+            var lastParent: Node;
+            var lastSymbol: Symbol;
+            var cutoffIndex: number = 0;
+            var index: number;
+            var specializedIndex: number = -1;
+            var spliceIndex: number;
+            Debug.assert(!result.length);
+            for (var i = 0; i < signatures.length; i++) {
+                var signature = signatures[i];
+                var symbol = signature.declaration && getSymbolOfNode(signature.declaration);
+                var parent = signature.declaration && signature.declaration.parent;
+                if (!lastSymbol || symbol === lastSymbol) {
+                    if (lastParent && parent === lastParent) {
+                        index++;
+                    }
+                    else {
+                        lastParent = parent;
+                        index = cutoffIndex;
+                    }
+                }
+                else {
+                    // current declaration belongs to a different symbol
+                    // set cutoffIndex so re-orderings in the future won't change result set from 0 to cutoffIndex
+                    index = cutoffIndex = result.length;
+                    lastParent = parent;
+                }
+                lastSymbol = symbol;
+
+                // specialized signatures always need to be placed before non-specialized signatures regardless
+                // of the cutoff position; see GH#1133
+                if (signature.hasStringLiterals) {
+                    specializedIndex++;
+                    spliceIndex = specializedIndex;
+                    // The cutoff index always needs to be greater than or equal to the specialized signature index
+                    // in order to prevent non-specialized signatures from being added before a specialized
+                    // signature.
+                    cutoffIndex++;
+                }
+                else {
+                    spliceIndex = index;
+                }
+
+                result.splice(spliceIndex, 0, signature);
+            }
+        }
+
+        function getSpreadArgumentIndex(args: Expression[]): number {
+            for (var i = 0; i < args.length; i++) {
+                if (args[i].kind === SyntaxKind.SpreadElementExpression) {
+                    return i;
+                }
+            }
+            return -1;
+        }
+
         function hasCorrectArity(node: CallLikeExpression, args: Expression[], signature: Signature) {
-            var adjustedArgCount: number;
-            var typeArguments: NodeArray<TypeNode>;
-            var callIsIncomplete: boolean;
+            var adjustedArgCount: number;            // Apparent number of arguments we will have in this call
+            var typeArguments: NodeArray<TypeNode>;  // Type arguments (undefined if none)
+            var callIsIncomplete: boolean;           // In incomplete call we want to be lenient when we have too few arguments
 
             if (node.kind === SyntaxKind.TaggedTemplateExpression) {
                 var tagExpression = <TaggedTemplateExpression>node;
@@ -5970,35 +6034,29 @@ module ts {
                 typeArguments = callExpression.typeArguments;
             }
 
-            Debug.assert(adjustedArgCount !== undefined, "'adjustedArgCount' undefined");
-            Debug.assert(callIsIncomplete !== undefined, "'callIsIncomplete' undefined");
-
-            return checkArity(adjustedArgCount, typeArguments, callIsIncomplete, signature);
-
-            /**
-             * @param adjustedArgCount The "apparent" number of arguments that we will have in this call.
-             * @param typeArguments    Type arguments node of the call if it exists; undefined otherwise.
-             * @param callIsIncomplete Whether or not a call is unfinished, and we should be "lenient" when we have too few arguments.
-             * @param signature        The signature whose arity we are comparing.
-             */
-            function checkArity(adjustedArgCount: number, typeArguments: NodeArray<TypeNode>, callIsIncomplete: boolean, signature: Signature): boolean {
-                // Too many arguments implies incorrect arity.
-                if (!signature.hasRestParameter && adjustedArgCount > signature.parameters.length) {
-                    return false;
-                }
-
-                // If the user supplied type arguments, but the number of type arguments does not match
-                // the declared number of type parameters, the call has an incorrect arity.
-                var hasRightNumberOfTypeArgs = !typeArguments ||
-                    (signature.typeParameters && typeArguments.length === signature.typeParameters.length);
-                if (!hasRightNumberOfTypeArgs) {
-                    return false;
-                }
-
-                // If the call is incomplete, we should skip the lower bound check.
-                var hasEnoughArguments = adjustedArgCount >= signature.minArgumentCount;
-                return callIsIncomplete || hasEnoughArguments;
+            // If the user supplied type arguments, but the number of type arguments does not match
+            // the declared number of type parameters, the call has an incorrect arity.
+            var hasRightNumberOfTypeArgs = !typeArguments ||
+                (signature.typeParameters && typeArguments.length === signature.typeParameters.length);
+            if (!hasRightNumberOfTypeArgs) {
+                return false;
             }
+
+            // If spread arguments are present, check that they correspond to a rest parameter. If so, no
+            // further checking is necessary.
+            var spreadArgIndex = getSpreadArgumentIndex(args);
+            if (spreadArgIndex >= 0) {
+                return signature.hasRestParameter && spreadArgIndex >= signature.parameters.length - 1;
+            }
+
+            // Too many arguments implies incorrect arity.
+            if (!signature.hasRestParameter && adjustedArgCount > signature.parameters.length) {
+                return false;
+            }
+
+            // If the call is incomplete, we should skip the lower bound check.
+            var hasEnoughArguments = adjustedArgCount >= signature.minArgumentCount;
+            return callIsIncomplete || hasEnoughArguments;
         }
 
         // If type has a single call signature and no other members, return that signature. Otherwise, return undefined.
@@ -6031,18 +6089,20 @@ module ts {
             // We perform two passes over the arguments. In the first pass we infer from all arguments, but use
             // wildcards for all context sensitive function expressions.
             for (var i = 0; i < args.length; i++) {
-                if (args[i].kind === SyntaxKind.OmittedExpression) {
-                    continue;
+                var arg = args[i];
+                if (arg.kind !== SyntaxKind.OmittedExpression) {
+                    var paramType = getTypeAtPosition(signature, arg.kind === SyntaxKind.SpreadElementExpression ? -1 : i);
+                    if (i === 0 && args[i].parent.kind === SyntaxKind.TaggedTemplateExpression) {
+                        var argType = globalTemplateStringsArrayType;
+                    }
+                    else {
+                        // For context sensitive arguments we pass the identityMapper, which is a signal to treat all
+                        // context sensitive function expressions as wildcards
+                        var mapper = excludeArgument && excludeArgument[i] !== undefined ? identityMapper : inferenceMapper;
+                        var argType = checkExpressionWithContextualType(arg, paramType, mapper);
+                    }
+                    inferTypes(context, argType, paramType);
                 }
-                var parameterType = getTypeAtPosition(signature, i);
-                if (i === 0 && args[i].parent.kind === SyntaxKind.TaggedTemplateExpression) {
-                    inferTypes(context, globalTemplateStringsArrayType, parameterType);
-                    continue;
-                }
-                // For context sensitive arguments we pass the identityMapper, which is a signal to treat all
-                // context sensitive function expressions as wildcards
-                var mapper = excludeArgument && excludeArgument[i] !== undefined ? identityMapper : inferenceMapper;
-                inferTypes(context, checkExpressionWithContextualType(args[i], parameterType, mapper), parameterType);
             }
 
             // In the second pass we visit only context sensitive arguments, and only those that aren't excluded, this
@@ -6050,13 +6110,11 @@ module ts {
             // as we construct types for contextually typed parameters)
             if (excludeArgument) {
                 for (var i = 0; i < args.length; i++) {
-                    if (args[i].kind === SyntaxKind.OmittedExpression) {
-                        continue;
-                    }
-                    // No need to special-case tagged templates; their excludeArgument value will be 'undefined'.
+                    // No need to check for omitted args and template expressions, their exlusion value is always undefined
                     if (excludeArgument[i] === false) {
-                        var parameterType = getTypeAtPosition(signature, i);
-                        inferTypes(context, checkExpressionWithContextualType(args[i], parameterType, inferenceMapper), parameterType);
+                        var arg = args[i];
+                        var paramType = getTypeAtPosition(signature, arg.kind === SyntaxKind.SpreadElementExpression ? -1 : i);
+                        inferTypes(context, checkExpressionWithContextualType(arg, paramType, inferenceMapper), paramType);
                     }
                 }
             }
@@ -6094,37 +6152,24 @@ module ts {
             return typeArgumentsAreAssignable;
         }
 
-        function checkApplicableSignature(node: CallLikeExpression, args: Node[], signature: Signature, relation: Map<RelationComparisonResult>, excludeArgument: boolean[], reportErrors: boolean) {
+        function checkApplicableSignature(node: CallLikeExpression, args: Expression[], signature: Signature, relation: Map<RelationComparisonResult>, excludeArgument: boolean[], reportErrors: boolean) {
             for (var i = 0; i < args.length; i++) {
                 var arg = args[i];
-                var argType: Type;
-
-                if (arg.kind === SyntaxKind.OmittedExpression) {
-                    continue;
-                }
-
-                var paramType = getTypeAtPosition(signature, i);
-
-                if (i === 0 && node.kind === SyntaxKind.TaggedTemplateExpression) {
-                    // A tagged template expression has something of a
-                    // "virtual" parameter with the "cooked" strings array type.
-                    argType = globalTemplateStringsArrayType;
-                }
-                else {
-                    // String literals get string literal types unless we're reporting errors
-                    argType = arg.kind === SyntaxKind.StringLiteral && !reportErrors
-                        ? getStringLiteralType(<LiteralExpression>arg)
-                        : checkExpressionWithContextualType(<LiteralExpression>arg, paramType, excludeArgument && excludeArgument[i] ? identityMapper : undefined);
-                }
-
-                // Use argument expression as error location when reporting errors
-                var isValidArgument = checkTypeRelatedTo(argType, paramType, relation, reportErrors ? arg : undefined,
-                    Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1);
-                if (!isValidArgument) {
-                    return false;
+                if (arg.kind !== SyntaxKind.OmittedExpression) {
+                    // Check spread elements against rest type (from arity check we know spread argument corresponds to a rest parameter)
+                    var paramType = getTypeAtPosition(signature, arg.kind === SyntaxKind.SpreadElementExpression ? -1 : i);
+                    // A tagged template expression provides a special first argument, and string literals get string literal types
+                    // unless we're reporting errors
+                    var argType = i === 0 && node.kind === SyntaxKind.TaggedTemplateExpression ? globalTemplateStringsArrayType :
+                        arg.kind === SyntaxKind.StringLiteral && !reportErrors ? getStringLiteralType(<LiteralExpression>arg) :
+                        checkExpressionWithContextualType(arg, paramType, excludeArgument && excludeArgument[i] ? identityMapper : undefined);
+                    // Use argument expression as error location when reporting errors
+                    if (!checkTypeRelatedTo(argType, paramType, relation, reportErrors ? arg : undefined,
+                        Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1)) {
+                        return false;
+                    }
                 }
             }
-
             return true;
         }
 
@@ -6191,8 +6236,8 @@ module ts {
             }
 
             var candidates = candidatesOutArray || [];
-            // collectCandidates fills up the candidates array directly
-            collectCandidates();
+            // reorderCandidates fills up the candidates array directly
+            reorderCandidates(signatures, candidates);
             if (!candidates.length) {
                 error(node, Diagnostics.Supplied_parameters_do_not_match_any_signature_of_call_target);
                 return resolveErrorCall(node);
@@ -6382,60 +6427,6 @@ module ts {
                 return undefined;
             }
 
-            // The candidate list orders groups in reverse, but within a group signatures are kept in declaration order
-            // A nit here is that we reorder only signatures that belong to the same symbol,
-            // so order how inherited signatures are processed is still preserved.
-            // interface A { (x: string): void }
-            // interface B extends A { (x: 'foo'): string }
-            // var b: B;
-            // b('foo') // <- here overloads should be processed as [(x:'foo'): string, (x: string): void]
-            function collectCandidates(): void {
-                var result = candidates;
-                var lastParent: Node;
-                var lastSymbol: Symbol;
-                var cutoffIndex: number = 0;
-                var index: number;
-                var specializedIndex: number = -1;
-                var spliceIndex: number;
-                Debug.assert(!result.length);
-                for (var i = 0; i < signatures.length; i++) {
-                    var signature = signatures[i];
-                    var symbol = signature.declaration && getSymbolOfNode(signature.declaration);
-                    var parent = signature.declaration && signature.declaration.parent;
-                    if (!lastSymbol || symbol === lastSymbol) {
-                        if (lastParent && parent === lastParent) {
-                            index++;
-                        }
-                        else {
-                            lastParent = parent;
-                            index = cutoffIndex;
-                        }
-                    }
-                    else {
-                        // current declaration belongs to a different symbol
-                        // set cutoffIndex so re-orderings in the future won't change result set from 0 to cutoffIndex
-                        index = cutoffIndex = result.length;
-                        lastParent = parent;
-                    }
-                    lastSymbol = symbol;
-
-                    // specialized signatures always need to be placed before non-specialized signatures regardless
-                    // of the cutoff position; see GH#1133
-                    if (signature.hasStringLiterals) {
-                        specializedIndex++;
-                        spliceIndex = specializedIndex;
-                        // The cutoff index always needs to be greater than or equal to the specialized signature index
-                        // in order to prevent non-specialized signatures from being added before a specialized
-                        // signature.
-                        cutoffIndex++;
-                    }
-                    else {
-                        spliceIndex = index;
-                    }
-
-                    result.splice(spliceIndex, 0, signature);
-                }
-            }
         }
 
         function resolveCallExpression(node: CallExpression, candidatesOutArray: Signature[]): Signature {
@@ -6491,6 +6482,13 @@ module ts {
         }
 
         function resolveNewExpression(node: NewExpression, candidatesOutArray: Signature[]): Signature {
+            if (node.arguments && languageVersion < ScriptTarget.ES6) {
+                var spreadIndex = getSpreadArgumentIndex(node.arguments);
+                if (spreadIndex >= 0) {
+                    error(node.arguments[spreadIndex], Diagnostics.Spread_operator_in_new_expressions_is_only_available_when_targeting_ECMAScript_6_and_higher);
+                }
+            }
+
             var expressionType = checkExpression(node.expression);
             // TS 1.0 spec: 4.11
             // If ConstructExpr is of type Any, Args can be any argument
@@ -6636,9 +6634,14 @@ module ts {
         }
 
         function getTypeAtPosition(signature: Signature, pos: number): Type {
+            if (pos >= 0) {
+                return signature.hasRestParameter ?
+                    pos < signature.parameters.length - 1 ? getTypeOfSymbol(signature.parameters[pos]) : getRestTypeOfSignature(signature) :
+                    pos < signature.parameters.length ? getTypeOfSymbol(signature.parameters[pos]) : anyType;
+            }
             return signature.hasRestParameter ?
-                pos < signature.parameters.length - 1 ? getTypeOfSymbol(signature.parameters[pos]) : getRestTypeOfSignature(signature) :
-                pos < signature.parameters.length ? getTypeOfSymbol(signature.parameters[pos]) : anyType;
+                getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]) :
+                anyArrayType;
         }
 
         function assignContextualParameterTypes(signature: Signature, context: Signature, mapper: TypeMapper) {
@@ -11085,9 +11088,32 @@ module ts {
                     }
                 }
             }
+
+            var checkLetConstNames =  languageVersion >= ScriptTarget.ES6 && (isLet(node) || isConst(node));
+
+            // 1. LexicalDeclaration : LetOrConst BindingList ;
+            // It is a Syntax Error if the BoundNames of BindingList contains "let".
+            // 2. ForDeclaration: ForDeclaration : LetOrConst ForBinding
+            // It is a Syntax Error if the BoundNames of ForDeclaration contains "let".
+
             // It is a SyntaxError if a VariableDeclaration or VariableDeclarationNoIn occurs within strict code 
             // and its Identifier is eval or arguments 
-            return checkGrammarEvalOrArgumentsInStrictMode(node, <Identifier>node.name);
+            return (checkLetConstNames && checkGrammarNameInLetOrConstDeclarations(node.name)) ||
+                checkGrammarEvalOrArgumentsInStrictMode(node, <Identifier>node.name);
+        }
+
+        function checkGrammarNameInLetOrConstDeclarations(name: Identifier | BindingPattern): boolean {
+            if (name.kind === SyntaxKind.Identifier) {
+                if ((<Identifier>name).text === "let") {
+                    return grammarErrorOnNode(name, Diagnostics.let_is_not_allowed_to_be_used_as_a_name_in_let_or_const_declarations);
+                }
+            }
+            else {
+                var elements = (<BindingPattern>name).elements;
+                for (var i = 0; i < elements.length; ++i) {
+                    checkGrammarNameInLetOrConstDeclarations(elements[i].name);
+                }
+            }
         }
 
         function checkGrammarVariableDeclarationList(declarationList: VariableDeclarationList): boolean {
diff --git a/src/compiler/diagnosticInformationMap.generated.ts b/src/compiler/diagnosticInformationMap.generated.ts
index 7d5681c706a..635336ac361 100644
--- a/src/compiler/diagnosticInformationMap.generated.ts
+++ b/src/compiler/diagnosticInformationMap.generated.ts
@@ -307,6 +307,7 @@ module ts {
         The_0_operator_cannot_be_applied_to_type_symbol: { code: 2469, category: DiagnosticCategory.Error, key: "The '{0}' operator cannot be applied to type 'symbol'." },
         Symbol_reference_does_not_refer_to_the_global_Symbol_constructor_object: { code: 2470, category: DiagnosticCategory.Error, key: "'Symbol' reference does not refer to the global Symbol constructor object." },
         A_computed_property_name_of_the_form_0_must_be_of_type_symbol: { code: 2471, category: DiagnosticCategory.Error, key: "A computed property name of the form '{0}' must be of type 'symbol'." },
+        Spread_operator_in_new_expressions_is_only_available_when_targeting_ECMAScript_6_and_higher: { code: 2472, category: DiagnosticCategory.Error, key: "Spread operator in 'new' expressions is only available when targeting ECMAScript 6 and higher." },
         Import_declaration_0_is_using_private_name_1: { code: 4000, category: DiagnosticCategory.Error, key: "Import declaration '{0}' is using private name '{1}'." },
         Type_parameter_0_of_exported_class_has_or_is_using_private_name_1: { code: 4002, category: DiagnosticCategory.Error, key: "Type parameter '{0}' of exported class has or is using private name '{1}'." },
         Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1: { code: 4004, category: DiagnosticCategory.Error, key: "Type parameter '{0}' of exported interface has or is using private name '{1}'." },
@@ -383,6 +384,7 @@ module ts {
         const_enum_member_initializer_was_evaluated_to_a_non_finite_value: { code: 4086, category: DiagnosticCategory.Error, key: "'const' enum member initializer was evaluated to a non-finite value." },
         const_enum_member_initializer_was_evaluated_to_disallowed_value_NaN: { code: 4087, category: DiagnosticCategory.Error, key: "'const' enum member initializer was evaluated to disallowed value 'NaN'." },
         Property_0_does_not_exist_on_const_enum_1: { code: 4088, category: DiagnosticCategory.Error, key: "Property '{0}' does not exist on 'const' enum '{1}'." },
+        let_is_not_allowed_to_be_used_as_a_name_in_let_or_const_declarations: { code: 4089, category: DiagnosticCategory.Error, key: "'let' is not allowed to be used as a name in 'let' or 'const' declarations." },
         The_current_host_does_not_support_the_0_option: { code: 5001, category: DiagnosticCategory.Error, key: "The current host does not support the '{0}' option." },
         Cannot_find_the_common_subdirectory_path_for_the_input_files: { code: 5009, category: DiagnosticCategory.Error, key: "Cannot find the common subdirectory path for the input files." },
         Cannot_read_file_0_Colon_1: { code: 5012, category: DiagnosticCategory.Error, key: "Cannot read file '{0}': {1}" },
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index e3c3be59a01..3da6e0bf22c 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1220,6 +1220,10 @@
         "category": "Error",
         "code": 2471
     },
+    "Spread operator in 'new' expressions is only available when targeting ECMAScript 6 and higher.": {
+        "category": "Error",
+        "code": 2472
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
@@ -1525,6 +1529,10 @@
         "category": "Error",
         "code": 4088
     },
+    "'let' is not allowed to be used as a name in 'let' or 'const' declarations.": {
+        "category": "Error",
+        "code": 4089
+    },
     "The current host does not support the '{0}' option.": {
         "category": "Error",
         "code": 5001
diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
index 63099bf2c60..31da36e3512 100644
--- a/src/compiler/emitter.ts
+++ b/src/compiler/emitter.ts
@@ -1998,7 +1998,7 @@ module ts {
                         break;
                     }
                     // _a .. _h, _j ... _z, _0, _1, ...
-                    name = "_" + (tempCount < 25 ? String.fromCharCode(tempCount + (tempCount < 8 ? 0: 1) + CharacterCodes.a) : tempCount - 25);
+                    name = "_" + (tempCount < 25 ? String.fromCharCode(tempCount + (tempCount < 8 ? 0 : 1) + CharacterCodes.a) : tempCount - 25);
                     tempCount++;
                 }
                 var result = <Identifier>createNode(SyntaxKind.Identifier);
@@ -2427,22 +2427,10 @@ module ts {
                 return true;
             }
 
-            function emitArrayLiteral(node: ArrayLiteralExpression) {
-                var elements = node.elements;
-                var length = elements.length;
-                if (length === 0) {
-                    write("[]");
-                    return;
-                }
-                if (languageVersion >= ScriptTarget.ES6) {
-                    write("[");
-                    emitList(elements, 0, elements.length, /*multiLine*/(node.flags & NodeFlags.MultiLine) !== 0,
-                        /*trailingComma*/ elements.hasTrailingComma);
-                    write("]");
-                    return;
-                }
+            function emitListWithSpread(elements: Expression[], multiLine: boolean, trailingComma: boolean) {
                 var pos = 0;
                 var group = 0;
+                var length = elements.length;
                 while (pos < length) {
                     // Emit using the pattern <group0>.concat(<group1>, <group2>, ...)
                     if (group === 1) {
@@ -2463,8 +2451,7 @@ module ts {
                             i++;
                         }
                         write("[");
-                        emitList(elements, pos, i - pos, /*multiLine*/ (node.flags & NodeFlags.MultiLine) !== 0,
-                            /*trailingComma*/ elements.hasTrailingComma);
+                        emitList(elements, pos, i - pos, multiLine, trailingComma && i === length);
                         write("]");
                         pos = i;
                     }
@@ -2475,6 +2462,23 @@ module ts {
                 }
             }
 
+            function emitArrayLiteral(node: ArrayLiteralExpression) {
+                var elements = node.elements;
+                if (elements.length === 0) {
+                    write("[]");
+                }
+                else if (languageVersion >= ScriptTarget.ES6) {
+                    write("[");
+                    emitList(elements, 0, elements.length, /*multiLine*/ (node.flags & NodeFlags.MultiLine) !== 0,
+                        /*trailingComma*/ elements.hasTrailingComma);
+                    write("]");
+                }
+                else {
+                    emitListWithSpread(elements, /*multiLine*/ (node.flags & NodeFlags.MultiLine) !== 0,
+                        /*trailingComma*/ elements.hasTrailingComma);
+                }
+            }
+
             function emitObjectLiteral(node: ObjectLiteralExpression) {
                 write("{");
                 var properties = node.properties;
@@ -2569,7 +2573,80 @@ module ts {
                 write("]");
             }
 
+            function hasSpreadElement(elements: Expression[]) {
+                return forEach(elements, e => e.kind === SyntaxKind.SpreadElementExpression);
+            }
+
+            function skipParentheses(node: Expression): Expression {
+                while (node.kind === SyntaxKind.ParenthesizedExpression || node.kind === SyntaxKind.TypeAssertionExpression) {
+                    node = (<ParenthesizedExpression | TypeAssertion>node).expression;
+                }
+                return node;
+            }
+
+            function emitCallTarget(node: Expression): Expression {
+                if (node.kind === SyntaxKind.Identifier || node.kind === SyntaxKind.ThisKeyword || node.kind === SyntaxKind.SuperKeyword) {
+                    emit(node);
+                    return node;
+                }
+                var temp = createTempVariable(node);
+                recordTempDeclaration(temp);
+                write("(");
+                emit(temp);
+                write(" = ");
+                emit(node);
+                write(")");
+                return temp;
+            }
+
+            function emitCallWithSpread(node: CallExpression) {
+                var target: Expression;
+                var expr = skipParentheses(node.expression);
+                if (expr.kind === SyntaxKind.PropertyAccessExpression) {
+                    // Target will be emitted as "this" argument
+                    target = emitCallTarget((<PropertyAccessExpression>expr).expression);
+                    write(".");
+                    emit((<PropertyAccessExpression>expr).name);
+                }
+                else if (expr.kind === SyntaxKind.ElementAccessExpression) {
+                    // Target will be emitted as "this" argument
+                    target = emitCallTarget((<PropertyAccessExpression>expr).expression);
+                    write("[");
+                    emit((<ElementAccessExpression>expr).argumentExpression);
+                    write("]");
+                }
+                else if (expr.kind === SyntaxKind.SuperKeyword) {
+                    target = expr;
+                    write("_super");
+                }
+                else {
+                    emit(node.expression);
+                }
+                write(".apply(");
+                if (target) {
+                    if (target.kind === SyntaxKind.SuperKeyword) {
+                        // Calls of form super(...) and super.foo(...)
+                        emitThis(target);
+                    }
+                    else {
+                        // Calls of form obj.foo(...)
+                        emit(target);
+                    }
+                }
+                else {
+                    // Calls of form foo(...)
+                    write("void 0");
+                }
+                write(", ");
+                emitListWithSpread(node.arguments, /*multiLine*/ false, /*trailingComma*/ false);
+                write(")");
+            }
+
             function emitCallExpression(node: CallExpression) {
+                if (languageVersion < ScriptTarget.ES6 && hasSpreadElement(node.arguments)) {
+                    emitCallWithSpread(node);
+                    return;
+                }
                 var superCall = false;
                 if (node.expression.kind === SyntaxKind.SuperKeyword) {
                     write("_super");
diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index 642821ffbcd..fd53064d058 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -336,11 +336,16 @@ module ts {
     }
 
     function fixupParentReferences(sourceFile: SourceFile) {
-        // normally parent references are set during binding.
-        // however here SourceFile data is used only for syntactic features so running the whole binding process is an overhead.
-        // walk over the nodes and set parent references
+        // normally parent references are set during binding. However, for clients that only need
+        // a syntax tree, and no semantic features, then the binding process is an unnecessary 
+        // overhead.  This functions allows us to set all the parents, without all the expense of
+        // binding.
+
         var parent: Node = sourceFile;
-        function walk(n: Node): void {
+        forEachChild(sourceFile, visitNode);
+        return;
+
+        function visitNode(n: Node): void {
             // walk down setting parents that differ from the parent we think it should be.  This
             // allows us to quickly bail out of setting parents for subtrees during incremental 
             // parsing
@@ -349,33 +354,53 @@ module ts {
 
                 var saveParent = parent;
                 parent = n;
-                forEachChild(n, walk);
+                forEachChild(n, visitNode);
                 parent = saveParent;
             }
         }
-
-        forEachChild(sourceFile, walk);
     }
 
-    function moveElementEntirelyPastChangeRange(element: IncrementalElement, delta: number) {
-        if (element.length) {
+    function shouldCheckNode(node: Node) {
+        switch (node.kind) {
+            case SyntaxKind.StringLiteral:
+            case SyntaxKind.NumericLiteral:
+            case SyntaxKind.Identifier:
+                return true;
+        }
+
+        return false;
+    }
+
+    function moveElementEntirelyPastChangeRange(element: IncrementalElement, isArray: boolean, delta: number, oldText: string, newText: string, aggressiveChecks: boolean) {
+        if (isArray) {
             visitArray(<IncrementalNodeArray>element);
         }
         else {
             visitNode(<IncrementalNode>element);
         }
+        return;
 
         function visitNode(node: IncrementalNode) {
+            if (aggressiveChecks && shouldCheckNode(node)) {
+                var text = oldText.substring(node.pos, node.end);
+            }
+
             // Ditch any existing LS children we may have created.  This way we can avoid 
             // moving them forward.
             node._children = undefined;
             node.pos += delta;
             node.end += delta;
 
+            if (aggressiveChecks && shouldCheckNode(node)) {
+                Debug.assert(text === newText.substring(node.pos, node.end));
+            }
+
             forEachChild(node, visitNode, visitArray);
+            checkNodePositions(node, aggressiveChecks);
         }
 
         function visitArray(array: IncrementalNodeArray) {
+            array._children = undefined;
             array.pos += delta;
             array.end += delta;
 
@@ -388,6 +413,7 @@ module ts {
     function adjustIntersectingElement(element: IncrementalElement, changeStart: number, changeRangeOldEnd: number, changeRangeNewEnd: number, delta: number) {
         Debug.assert(element.end >= changeStart, "Adjusting an element that was entirely before the change range");
         Debug.assert(element.pos <= changeRangeOldEnd, "Adjusting an element that was entirely after the change range");
+        Debug.assert(element.pos <= element.end);
 
         // We have an element that intersects the change range in some way.  It may have its
         // start, or its end (or both) in the changed range.  We want to adjust any part
@@ -459,14 +485,36 @@ module ts {
         }
     }
 
-    function updateTokenPositionsAndMarkElements(node: IncrementalNode, changeStart: number, changeRangeOldEnd: number, changeRangeNewEnd: number, delta: number): void {
-        visitNode(node);
+    function checkNodePositions(node: Node, aggressiveChecks: boolean) {
+        if (aggressiveChecks) {
+            var pos = node.pos;
+            forEachChild(node, child => {
+                Debug.assert(child.pos >= pos);
+                pos = child.end;
+            });
+            Debug.assert(pos <= node.end);
+        }
+    }
+
+    function updateTokenPositionsAndMarkElements(
+        sourceFile: IncrementalNode,
+        changeStart: number,
+        changeRangeOldEnd: number,
+        changeRangeNewEnd: number,
+        delta: number,
+        oldText: string,
+        newText: string,
+        aggressiveChecks: boolean): void {
+
+        visitNode(sourceFile);
+        return;
 
         function visitNode(child: IncrementalNode) {
+            Debug.assert(child.pos <= child.end);
             if (child.pos > changeRangeOldEnd) {
                 // Node is entirely past the change range.  We need to move both its pos and 
                 // end, forward or backward appropriately.
-                moveElementEntirelyPastChangeRange(child, delta);
+                moveElementEntirelyPastChangeRange(child, /*isArray:*/ false, delta, oldText, newText, aggressiveChecks);
                 return;
             }
 
@@ -476,44 +524,50 @@ module ts {
             var fullEnd = child.end;
             if (fullEnd >= changeStart) {
                 child.intersectsChange = true;
+                child._children = undefined;
 
                 // Adjust the pos or end (or both) of the intersecting element accordingly.
                 adjustIntersectingElement(child, changeStart, changeRangeOldEnd, changeRangeNewEnd, delta);
                 forEachChild(child, visitNode, visitArray);
+
+                checkNodePositions(child, aggressiveChecks);
                 return;
             }
 
             // Otherwise, the node is entirely before the change range.  No need to do anything with it.
+            Debug.assert(fullEnd < changeStart);
         }
 
         function visitArray(array: IncrementalNodeArray) {
+            Debug.assert(array.pos <= array.end);
             if (array.pos > changeRangeOldEnd) {
                 // Array is entirely after the change range.  We need to move it, and move any of
                 // its children.
-                moveElementEntirelyPastChangeRange(array, delta);
+                moveElementEntirelyPastChangeRange(array, /*isArray:*/ true, delta, oldText, newText, aggressiveChecks);
+                return;
             }
-            else {
-                // Check if the element intersects the change range.  If it does, then it is not
-                // reusable.  Also, we'll need to recurse to see what constituent portions we may
-                // be able to use.
-                var fullEnd = array.end;
-                if (fullEnd >= changeStart) {
-                    array.intersectsChange = true;
 
-                    // Adjust the pos or end (or both) of the intersecting array accordingly.
-                    adjustIntersectingElement(array, changeStart, changeRangeOldEnd, changeRangeNewEnd, delta);
-                    for (var i = 0, n = array.length; i < n; i++) {
-                        visitNode(array[i]);
-                    }
+            // Check if the element intersects the change range.  If it does, then it is not
+            // reusable.  Also, we'll need to recurse to see what constituent portions we may
+            // be able to use.
+            var fullEnd = array.end;
+            if (fullEnd >= changeStart) {
+                array.intersectsChange = true;
+                array._children = undefined;
+
+                // Adjust the pos or end (or both) of the intersecting array accordingly.
+                adjustIntersectingElement(array, changeStart, changeRangeOldEnd, changeRangeNewEnd, delta);
+                for (var i = 0, n = array.length; i < n; i++) {
+                    visitNode(array[i]);
                 }
-                // else {
-                // Otherwise, the array is entirely before the change range.  No need to do anything with it.
-                // }
+                return;
             }
+
+            // Otherwise, the array is entirely before the change range.  No need to do anything with it.
+            Debug.assert(fullEnd < changeStart);
         }
     }
 
-
     function extendToAffectedRange(sourceFile: SourceFile, changeRange: TextChangeRange): TextChangeRange {
         // Consider the following code:
         //      void foo() { /; }
@@ -534,6 +588,7 @@ module ts {
         // start of the tree.
         for (var i = 0; start > 0 && i <= maxLookahead; i++) {
             var nearestNode = findNearestNodeStartingBeforeOrAtPosition(sourceFile, start);
+            Debug.assert(nearestNode.pos <= start);
             var position = nearestNode.pos;
 
             start = Math.max(0, position - 1);
@@ -640,6 +695,22 @@ module ts {
         }
     }
 
+    function checkChangeRange(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks: boolean) {
+        var oldText = sourceFile.text;
+        if (textChangeRange) {
+            Debug.assert((oldText.length - textChangeRange.span.length + textChangeRange.newLength) === newText.length);
+
+            if (aggressiveChecks || Debug.shouldAssert(AssertionLevel.VeryAggressive)) {
+                var oldTextPrefix = oldText.substr(0, textChangeRange.span.start);
+                var newTextPrefix = newText.substr(0, textChangeRange.span.start);
+                Debug.assert(oldTextPrefix === newTextPrefix);
+
+                var oldTextSuffix = oldText.substring(textSpanEnd(textChangeRange.span), oldText.length);
+                var newTextSuffix = newText.substring(textSpanEnd(textChangeRangeNewSpan(textChangeRange)), newText.length);
+                Debug.assert(oldTextSuffix === newTextSuffix);
+            }
+        }
+    }
 
     // Produces a new SourceFile for the 'newText' provided. The 'textChangeRange' parameter 
     // indicates what changed between the 'text' that this SourceFile has and the 'newText'.
@@ -650,7 +721,10 @@ module ts {
     // from this SourceFile that are being held onto may change as a result (including 
     // becoming detached from any SourceFile).  It is recommended that this SourceFile not
     // be used once 'update' is called on it.
-    export function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange): SourceFile {
+    export function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile {
+        aggressiveChecks = aggressiveChecks || Debug.shouldAssert(AssertionLevel.Aggressive);
+
+        checkChangeRange(sourceFile, newText, textChangeRange, aggressiveChecks);
         if (textChangeRangeIsUnchanged(textChangeRange)) {
             // if the text didn't change, then we can just return our current source file as-is.
             return sourceFile;
@@ -659,14 +733,32 @@ module ts {
         if (sourceFile.statements.length === 0) {
             // If we don't have any statements in the current source file, then there's no real
             // way to incrementally parse.  So just do a full parse instead.
-            return parseSourceFile(sourceFile.fileName, newText, sourceFile.languageVersion,/*syntaxCursor*/ undefined, /*setNodeParents*/ true)
+            return parseSourceFile(sourceFile.fileName, newText, sourceFile.languageVersion, /*syntaxCursor*/ undefined, /*setNodeParents*/ true)
         }
 
+        // Make sure we're not trying to incrementally update a source file more than once.  Once
+        // we do an update the original source file is considered unusbale from that point onwards. 
+        //
+        // This is because we do incremental parsing in-place.  i.e. we take nodes from the old
+        // tree and give them new positions and parents.  From that point on, trusting the old
+        // tree at all is not possible as far too much of it may violate invariants.
+        var incrementalSourceFile = <IncrementalNode><Node>sourceFile;
+        Debug.assert(!incrementalSourceFile.hasBeenIncrementallyParsed);
+        incrementalSourceFile.hasBeenIncrementallyParsed = true;
+
+        var oldText = sourceFile.text;
         var syntaxCursor = createSyntaxCursor(sourceFile);
 
         // Make the actual change larger so that we know to reparse anything whose lookahead 
         // might have intersected the change.
         var changeRange = extendToAffectedRange(sourceFile, textChangeRange);
+        checkChangeRange(sourceFile, newText, changeRange, aggressiveChecks);
+
+        // Ensure that extending the affected range only moved the start of the change range 
+        // earlier in the file.
+        Debug.assert(changeRange.span.start <= textChangeRange.span.start);
+        Debug.assert(textSpanEnd(changeRange.span) === textSpanEnd(textChangeRange.span));
+        Debug.assert(textSpanEnd(textChangeRangeNewSpan(changeRange)) === textSpanEnd(textChangeRangeNewSpan(textChangeRange)));
 
         // The is the amount the nodes after the edit range need to be adjusted.  It can be 
         // positive (if the edit added characters), negative (if the edit deleted characters)
@@ -674,8 +766,8 @@ module ts {
         var delta = textChangeRangeNewSpan(changeRange).length - changeRange.span.length;
 
         // If we added or removed characters during the edit, then we need to go and adjust all
-        // the nodes after the edit.  Those nodes may move forward down (if we inserted chars)
-        // or they may move backward (if we deleted chars).
+        // the nodes after the edit.  Those nodes may move forward (if we inserted chars) or they 
+        // may move backward (if we deleted chars).
         //
         // Doing this helps us out in two ways.  First, it means that any nodes/tokens we want
         // to reuse are already at the appropriate position in the new text.  That way when we
@@ -692,8 +784,8 @@ module ts {
         //
         // Also, mark any syntax elements that intersect the changed span.  We know, up front,
         // that we cannot reuse these elements.
-        updateTokenPositionsAndMarkElements(<IncrementalNode><Node>sourceFile,
-            changeRange.span.start, textSpanEnd(changeRange.span), textSpanEnd(textChangeRangeNewSpan(changeRange)), delta);
+        updateTokenPositionsAndMarkElements(incrementalSourceFile,
+            changeRange.span.start, textSpanEnd(changeRange.span), textSpanEnd(textChangeRangeNewSpan(changeRange)), delta, oldText, newText, aggressiveChecks);
 
         // Now that we've set up our internal incremental state just proceed and parse the
         // source file in the normal fashion.  When possible the parser will retrieve and
@@ -733,6 +825,7 @@ module ts {
     }
 
     interface IncrementalNode extends Node, IncrementalElement {
+        hasBeenIncrementallyParsed: boolean
     }
 
     interface IncrementalNodeArray extends NodeArray<IncrementalNode>, IncrementalElement {
@@ -768,7 +861,7 @@ module ts {
                     // Much of the time the parser will need the very next node in the array that 
                     // we just returned a node from.So just simply check for that case and move 
                     // forward in the array instead of searching for the node again.
-                    if (current && current.end === position && currentArrayIndex < currentArray.length) {
+                    if (current && current.end === position && currentArrayIndex < (currentArray.length - 1)) {
                         currentArrayIndex++;
                         current = currentArray[currentArrayIndex];
                     }
@@ -804,6 +897,7 @@ module ts {
 
             // Recurse into the source file to find the highest node at this position.
             forEachChild(sourceFile, visitNode, visitArray);
+            return;
 
             function visitNode(node: Node) {
                 if (position >= node.pos && position < node.end) {
@@ -863,7 +957,6 @@ module ts {
         var identifiers: Map<string> = {};
         var identifierCount = 0;
         var nodeCount = 0;
-        var scanner: Scanner;
         var token: SyntaxKind;
 
         var sourceFile = <SourceFile>createNode(SyntaxKind.SourceFile, /*pos*/ 0);
@@ -956,7 +1049,7 @@ module ts {
         var parseErrorBeforeNextFinishedNode: boolean = false;
 
         // Create and prime the scanner before parsing the source elements.
-        scanner = createScanner(languageVersion, /*skipTrivia*/ true, sourceText, scanError);
+        var scanner = createScanner(languageVersion, /*skipTrivia*/ true, sourceText, scanError);
         token = nextToken();
 
         processReferenceComments(sourceFile);
@@ -975,6 +1068,7 @@ module ts {
             fixupParentReferences(sourceFile);
         }
 
+        syntaxCursor = undefined;
         return sourceFile;
 
         function setContextFlag(val: Boolean, flag: ParserContextFlags) {
@@ -1422,7 +1516,6 @@ module ts {
                 case ParsingContext.TypeParameters:
                     return isIdentifier();
                 case ParsingContext.ArgumentExpressions:
-                    return token === SyntaxKind.CommaToken || isStartOfExpression();
                 case ParsingContext.ArrayLiteralMembers:
                     return token === SyntaxKind.CommaToken || token === SyntaxKind.DotDotDotToken || isStartOfExpression();
                 case ParsingContext.Parameters:
@@ -1575,8 +1668,8 @@ module ts {
             return result;
         }
 
-        function parseListElement<T extends Node>(kind: ParsingContext, parseElement: () => T): T {
-            var node = currentNode(kind);
+        function parseListElement<T extends Node>(parsingContext: ParsingContext, parseElement: () => T): T {
+            var node = currentNode(parsingContext);
             if (node) {
                 return <T>consumeNode(node);
             }
@@ -1733,29 +1826,10 @@ module ts {
                     case SyntaxKind.InterfaceDeclaration:
                     case SyntaxKind.ModuleDeclaration:
                     case SyntaxKind.EnumDeclaration:
-
-                    // Keep in sync with isStatement:
-                    case SyntaxKind.FunctionDeclaration:
-                    case SyntaxKind.VariableStatement:
-                    case SyntaxKind.Block:
-                    case SyntaxKind.IfStatement:
-                    case SyntaxKind.ExpressionStatement:
-                    case SyntaxKind.ThrowStatement:
-                    case SyntaxKind.ReturnStatement:
-                    case SyntaxKind.SwitchStatement:
-                    case SyntaxKind.BreakStatement:
-                    case SyntaxKind.ContinueStatement:
-                    case SyntaxKind.ForInStatement:
-                    case SyntaxKind.ForStatement:
-                    case SyntaxKind.WhileStatement:
-                    case SyntaxKind.WithStatement:
-                    case SyntaxKind.EmptyStatement:
-                    case SyntaxKind.TryStatement:
-                    case SyntaxKind.LabeledStatement:
-                    case SyntaxKind.DoStatement:
-                    case SyntaxKind.DebuggerStatement:
                         return true;
                 }
+
+                return isReusableStatement(node);
             }
 
             return false;
@@ -1861,9 +1935,13 @@ module ts {
         }
 
         function isReusableParameter(node: Node) {
-            // TODO: this most likely needs the same initializer check that 
-            // isReusableVariableDeclaration has.
-            return node.kind === SyntaxKind.Parameter;
+            if (node.kind !== SyntaxKind.Parameter) {
+                return false;
+            }
+
+            // See the comment in isReusableVariableDeclaration for why we do this.
+            var parameter = <ParameterDeclaration>node;
+            return parameter.initializer === undefined;
         }
 
         // Returns true if we should abort parsing.
@@ -3528,12 +3606,6 @@ module ts {
             return finishNode(node);
         }
 
-        function parseAssignmentExpressionOrOmittedExpression(): Expression {
-            return token === SyntaxKind.CommaToken
-                ? <Expression>createNode(SyntaxKind.OmittedExpression)
-                : parseAssignmentExpressionOrHigher();
-        }
-
         function parseSpreadElement(): Expression {
             var node = <SpreadElementExpression>createNode(SyntaxKind.SpreadElementExpression);
             parseExpected(SyntaxKind.DotDotDotToken);
@@ -3541,19 +3613,21 @@ module ts {
             return finishNode(node);
         }
 
-        function parseArrayLiteralElement(): Expression {
-            return token === SyntaxKind.DotDotDotToken ? parseSpreadElement() : parseAssignmentExpressionOrOmittedExpression();
+        function parseArgumentOrArrayLiteralElement(): Expression {
+            return token === SyntaxKind.DotDotDotToken ? parseSpreadElement() :
+                token === SyntaxKind.CommaToken ? <Expression>createNode(SyntaxKind.OmittedExpression) :
+                parseAssignmentExpressionOrHigher();
         }
 
         function parseArgumentExpression(): Expression {
-            return allowInAnd(parseAssignmentExpressionOrOmittedExpression);
+            return allowInAnd(parseArgumentOrArrayLiteralElement);
         }
 
         function parseArrayLiteralExpression(): ArrayLiteralExpression {
             var node = <ArrayLiteralExpression>createNode(SyntaxKind.ArrayLiteralExpression);
             parseExpected(SyntaxKind.OpenBracketToken);
             if (scanner.hasPrecedingLineBreak()) node.flags |= NodeFlags.MultiLine;
-            node.elements = parseDelimitedList(ParsingContext.ArrayLiteralMembers, parseArrayLiteralElement);
+            node.elements = parseDelimitedList(ParsingContext.ArrayLiteralMembers, parseArgumentOrArrayLiteralElement);
             parseExpected(SyntaxKind.CloseBracketToken);
             return finishNode(node);
         }
diff --git a/src/harness/fourslash.ts b/src/harness/fourslash.ts
index d829ce0b83e..603a78b5f75 100644
--- a/src/harness/fourslash.ts
+++ b/src/harness/fourslash.ts
@@ -16,6 +16,7 @@
 /// <reference path='..\services\services.ts' />
 /// <reference path='harnessLanguageService.ts' />
 /// <reference path='harness.ts' />
+/// <reference path='fourslashRunner.ts' />
 
 module FourSlash {
     ts.disableIncrementalParsing = false;
@@ -245,11 +246,9 @@ module FourSlash {
 
     export class TestState {
         // Language service instance
-        public languageServiceShimHost: Harness.LanguageService.TypeScriptLS;
+        private languageServiceAdapterHost: Harness.LanguageService.LanguageServiceAdapterHost;
         private languageService: ts.LanguageService;
-
-        // A reference to the language service's compiler state's compiler instance
-        private compiler: () => { getSyntaxTree(fileName: string): ts.SourceFile };
+        private cancellationToken: TestCancellationToken;
 
         // The current caret position in the active file
         public currentCaretPosition = 0;
@@ -263,8 +262,6 @@ module FourSlash {
 
         public formatCodeOptions: ts.FormatCodeOptions;
 
-        public cancellationToken: TestCancellationToken;
-
         private scenarioActions: string[] = [];
         private taoInvalidReason: string = null;
 
@@ -275,19 +272,31 @@ module FourSlash {
         private addMatchedInputFile(referenceFilePath: string) {
             var inputFile = this.inputFiles[referenceFilePath];
             if (inputFile && !Harness.isLibraryFile(referenceFilePath)) {
-                this.languageServiceShimHost.addScript(referenceFilePath, inputFile);
+                this.languageServiceAdapterHost.addScript(referenceFilePath, inputFile);
             }
         }
 
-        constructor(public testData: FourSlashData) {
-            // Initialize the language service with all the scripts
+        private getLanguageServiceAdapter(testType: FourSlashTestType, cancellationToken: TestCancellationToken, compilationOptions: ts.CompilerOptions): Harness.LanguageService.LanguageServiceAdapter {
+            switch (testType) {
+                case FourSlashTestType.Native:
+                    return new Harness.LanguageService.NativeLanugageServiceAdapter(cancellationToken, compilationOptions);
+                case FourSlashTestType.Shims:
+                    return new Harness.LanguageService.ShimLanugageServiceAdapter(cancellationToken, compilationOptions);
+                default:
+                    throw new Error("Unknown FourSlash test type: ");
+            }
+        }
+
+        constructor(private basePath: string, private testType: FourSlashTestType, public testData: FourSlashData) {
+            // Create a new Services Adapter
             this.cancellationToken = new TestCancellationToken();
-            this.languageServiceShimHost = new Harness.LanguageService.TypeScriptLS(this.cancellationToken);
+            var compilationOptions = convertGlobalOptionsToCompilerOptions(this.testData.globalOptions);
+            var languageServiceAdapter = this.getLanguageServiceAdapter(testType, this.cancellationToken, compilationOptions);
+            this.languageServiceAdapterHost = languageServiceAdapter.getHost();
+            this.languageService = languageServiceAdapter.getLanguageService();
 
-            var compilationSettings = convertGlobalOptionsToCompilerOptions(this.testData.globalOptions);
-            this.languageServiceShimHost.setCompilationSettings(compilationSettings);
-
-            var startResolveFileRef: FourSlashFile = undefined;
+            // Initialize the language service with all the scripts
+            var startResolveFileRef: FourSlashFile;
 
             ts.forEach(testData.files, file => {
                 // Create map between fileName and its content for easily looking up when resolveReference flag is specified
@@ -302,18 +311,16 @@ module FourSlash {
 
             if (startResolveFileRef) {
                 // Add the entry-point file itself into the languageServiceShimHost
-                this.languageServiceShimHost.addScript(startResolveFileRef.fileName, startResolveFileRef.content);
+                this.languageServiceAdapterHost.addScript(startResolveFileRef.fileName, startResolveFileRef.content);
 
-                var jsonResolvedResult = JSON.parse(this.languageServiceShimHost.getCoreService().getPreProcessedFileInfo(startResolveFileRef.fileName,
-                    createScriptSnapShot(startResolveFileRef.content)));
-                var resolvedResult = jsonResolvedResult.result;
-                var referencedFiles: ts.IFileReference[] = resolvedResult.referencedFiles;
-                var importedFiles: ts.IFileReference[] = resolvedResult.importedFiles;
+                var resolvedResult = languageServiceAdapter.getPreProcessedFileInfo(startResolveFileRef.fileName, startResolveFileRef.content);
+                var referencedFiles: ts.FileReference[] = resolvedResult.referencedFiles;
+                var importedFiles: ts.FileReference[] = resolvedResult.importedFiles;
 
                 // Add triple reference files into language-service host
                 ts.forEach(referencedFiles, referenceFile => {
                     // Fourslash insert tests/cases/fourslash into inputFile.unitName so we will properly append the same base directory to refFile path
-                    var referenceFilePath = "tests/cases/fourslash/" + referenceFile.path;
+                    var referenceFilePath = this.basePath + '/' + referenceFile.fileName;
                     this.addMatchedInputFile(referenceFilePath);
                 });
 
@@ -321,29 +328,24 @@ module FourSlash {
                 ts.forEach(importedFiles, importedFile => {
                     // Fourslash insert tests/cases/fourslash into inputFile.unitName and import statement doesn't require ".ts"
                     // so convert them before making appropriate comparison
-                    var importedFilePath = "tests/cases/fourslash/" + importedFile.path + ".ts";
+                    var importedFilePath = this.basePath + '/' + importedFile.fileName + ".ts";
                     this.addMatchedInputFile(importedFilePath);
                 });
 
                 // Check if no-default-lib flag is false and if so add default library
                 if (!resolvedResult.isLibFile) {
-                    this.languageServiceShimHost.addDefaultLibrary();
+                    this.languageServiceAdapterHost.addScript(Harness.Compiler.defaultLibFileName, Harness.Compiler.defaultLibSourceFile.text);
                 }
             } else {
                 // resolveReference file-option is not specified then do not resolve any files and include all inputFiles
                 ts.forEachKey(this.inputFiles, fileName => {
                     if (!Harness.isLibraryFile(fileName)) {
-                        this.languageServiceShimHost.addScript(fileName, this.inputFiles[fileName]);
+                        this.languageServiceAdapterHost.addScript(fileName, this.inputFiles[fileName]);
                     }
                 });
-                this.languageServiceShimHost.addDefaultLibrary();
+                this.languageServiceAdapterHost.addScript(Harness.Compiler.defaultLibFileName, Harness.Compiler.defaultLibSourceFile.text);
             }
 
-            // Sneak into the language service and get its compiler so we can examine the syntax trees
-            this.languageService = this.languageServiceShimHost.getLanguageService().languageService;
-            var compilerState = (<any>this.languageService).compiler;
-            this.compiler = () => compilerState.compiler;
-
             this.formatCodeOptions = {
                 IndentSize: 4,
                 TabSize: 4,
@@ -369,6 +371,11 @@ module FourSlash {
             this.openFile(0);
         }
 
+        private getFileContent(fileName: string): string {
+            var script = this.languageServiceAdapterHost.getScriptInfo(fileName);
+            return script.content;
+        }
+
         // Entry points from fourslash.ts
         public goToMarker(name = '') {
             var marker = this.getMarkerByName(name);
@@ -376,8 +383,8 @@ module FourSlash {
                 this.openFile(marker.fileName);
             }
 
-            var scriptSnapshot = this.languageServiceShimHost.getScriptSnapshot(marker.fileName);
-            if (marker.position === -1 || marker.position > scriptSnapshot.getLength()) {
+            var content = this.getFileContent(marker.fileName);
+            if (marker.position === -1 || marker.position > content.length) {
                 throw new Error('Marker "' + name + '" has been invalidated by unrecoverable edits to the file.');
             }
             this.lastKnownMarker = name;
@@ -387,14 +394,14 @@ module FourSlash {
         public goToPosition(pos: number) {
             this.currentCaretPosition = pos;
 
-            var lineStarts = ts.computeLineStarts(this.getCurrentFileContent());
+            var lineStarts = ts.computeLineStarts(this.getFileContent(this.activeFile.fileName));
             var lineCharPos = ts.computeLineAndCharacterOfPosition(lineStarts, pos);
             this.scenarioActions.push('<MoveCaretToLineAndChar LineNumber="' + lineCharPos.line + '" CharNumber="' + lineCharPos.character + '" />');
         }
 
         public moveCaretRight(count = 1) {
             this.currentCaretPosition += count;
-            this.currentCaretPosition = Math.min(this.currentCaretPosition, this.languageServiceShimHost.getScriptSnapshot(this.activeFile.fileName).getLength());
+            this.currentCaretPosition = Math.min(this.currentCaretPosition, this.getFileContent(this.activeFile.fileName).length);
             if (count > 0) {
                 this.scenarioActions.push('<MoveCaretRight NumberOfChars="' + count + '" />');
             } else {
@@ -453,7 +460,7 @@ module FourSlash {
         private getAllDiagnostics(): ts.Diagnostic[] {
             var diagnostics: ts.Diagnostic[] = [];
 
-            var fileNames = JSON.parse(this.languageServiceShimHost.getScriptFileNames());
+            var fileNames = this.languageServiceAdapterHost.getFilenames();
             for (var i = 0, n = fileNames.length; i < n; i++) {
                 diagnostics.push.apply(this.getDiagnostics(fileNames[i]));
             }
@@ -805,7 +812,6 @@ module FourSlash {
             }
         }
 
-
         public verifyQuickInfoDisplayParts(kind: string, kindModifiers: string, textSpan: { start: number; length: number; },
             displayParts: ts.SymbolDisplayPart[],
             documentation: ts.SymbolDisplayPart[]) {
@@ -1211,8 +1217,7 @@ module FourSlash {
                 var file = this.testData.files[i];
                 var active = (this.activeFile === file);
                 Harness.IO.log('=== Script (' + file.fileName + ') ' + (active ? '(active, cursor at |)' : '') + ' ===');
-                var snapshot = this.languageServiceShimHost.getScriptSnapshot(file.fileName);
-                var content = snapshot.getText(0, snapshot.getLength());
+                var content = this.getFileContent(file.fileName);
                 if (active) {
                     content = content.substr(0, this.currentCaretPosition) + (makeCaretVisible ? '|' : "") + content.substr(this.currentCaretPosition);
                 }
@@ -1246,8 +1251,7 @@ module FourSlash {
         }
 
         public printContext() {
-            var fileNames: string[] = JSON.parse(this.languageServiceShimHost.getScriptFileNames());
-            ts.forEach(fileNames, Harness.IO.log);
+            ts.forEach(this.languageServiceAdapterHost.getFilenames(), Harness.IO.log);
         }
 
         public deleteChar(count = 1) {
@@ -1260,7 +1264,7 @@ module FourSlash {
 
             for (var i = 0; i < count; i++) {
                 // Make the edit
-                this.languageServiceShimHost.editScript(this.activeFile.fileName, offset, offset + 1, ch);
+                this.languageServiceAdapterHost.editScript(this.activeFile.fileName, offset, offset + 1, ch);
                 this.updateMarkersForEdit(this.activeFile.fileName, offset, offset + 1, ch);
 
                 if (i % checkCadence === 0) {
@@ -1287,7 +1291,7 @@ module FourSlash {
         public replace(start: number, length: number, text: string) {
             this.taoInvalidReason = 'replace NYI';
 
-            this.languageServiceShimHost.editScript(this.activeFile.fileName, start, start + length, text);
+            this.languageServiceAdapterHost.editScript(this.activeFile.fileName, start, start + length, text);
             this.updateMarkersForEdit(this.activeFile.fileName, start, start + length, text);
             this.checkPostEditInvariants();
         }
@@ -1302,7 +1306,7 @@ module FourSlash {
             for (var i = 0; i < count; i++) {
                 offset--;
                 // Make the edit
-                this.languageServiceShimHost.editScript(this.activeFile.fileName, offset, offset + 1, ch);
+                this.languageServiceAdapterHost.editScript(this.activeFile.fileName, offset, offset + 1, ch);
                 this.updateMarkersForEdit(this.activeFile.fileName, offset, offset + 1, ch);
 
                 if (i % checkCadence === 0) {
@@ -1347,7 +1351,7 @@ module FourSlash {
             for (var i = 0; i < text.length; i++) {
                 // Make the edit
                 var ch = text.charAt(i);
-                this.languageServiceShimHost.editScript(this.activeFile.fileName, offset, offset, ch);
+                this.languageServiceAdapterHost.editScript(this.activeFile.fileName, offset, offset, ch);
                 this.languageService.getBraceMatchingAtPosition(this.activeFile.fileName, offset);
 
                 this.updateMarkersForEdit(this.activeFile.fileName, offset, offset, ch);
@@ -1390,7 +1394,7 @@ module FourSlash {
 
             var start = this.currentCaretPosition;
             var offset = this.currentCaretPosition;
-            this.languageServiceShimHost.editScript(this.activeFile.fileName, offset, offset, text);
+            this.languageServiceAdapterHost.editScript(this.activeFile.fileName, offset, offset, text);
             this.updateMarkersForEdit(this.activeFile.fileName, offset, offset, text);
             this.checkPostEditInvariants();
             offset += text.length;
@@ -1412,14 +1416,19 @@ module FourSlash {
         }
 
         private checkPostEditInvariants() {
+            if (this.testType !== FourSlashTestType.Native) { 
+                // getSourcefile() results can not be serialized. Only perform these verifications 
+                // if running against a native LS object.
+                return;
+            }
+
             var incrementalSourceFile = this.languageService.getSourceFile(this.activeFile.fileName);
             Utils.assertInvariants(incrementalSourceFile, /*parent:*/ undefined);
 
             var incrementalSyntaxDiagnostics = incrementalSourceFile.parseDiagnostics;
 
             // Check syntactic structure
-            var snapshot = this.languageServiceShimHost.getScriptSnapshot(this.activeFile.fileName);
-            var content = snapshot.getText(0, snapshot.getLength());
+            var content = this.getFileContent(this.activeFile.fileName);
 
             var referenceSourceFile = ts.createLanguageServiceSourceFile(
                 this.activeFile.fileName, createScriptSnapShot(content), ts.ScriptTarget.Latest, /*version:*/ "0", /*setNodeParents:*/ false);
@@ -1433,7 +1442,7 @@ module FourSlash {
             // The caret can potentially end up between the \r and \n, which is confusing. If
             // that happens, move it back one character
             if (this.currentCaretPosition > 0) {
-                var ch = this.languageServiceShimHost.getScriptSnapshot(this.activeFile.fileName).getText(this.currentCaretPosition - 1, this.currentCaretPosition);
+                var ch = this.getFileContent(this.activeFile.fileName).substring(this.currentCaretPosition - 1, this.currentCaretPosition);
                 if (ch === '\r') {
                     this.currentCaretPosition--;
                 }
@@ -1446,10 +1455,9 @@ module FourSlash {
             var runningOffset = 0;
             edits = edits.sort((a, b) => a.span.start - b.span.start);
             // Get a snapshot of the content of the file so we can make sure any formatting edits didn't destroy non-whitespace characters
-            var snapshot = this.languageServiceShimHost.getScriptSnapshot(fileName);
-            var oldContent = snapshot.getText(0, snapshot.getLength());
+            var oldContent = this.getFileContent(this.activeFile.fileName);
             for (var j = 0; j < edits.length; j++) {
-                this.languageServiceShimHost.editScript(fileName, edits[j].span.start + runningOffset, ts.textSpanEnd(edits[j].span) + runningOffset, edits[j].newText);
+                this.languageServiceAdapterHost.editScript(fileName, edits[j].span.start + runningOffset, ts.textSpanEnd(edits[j].span) + runningOffset, edits[j].newText);
                 this.updateMarkersForEdit(fileName, edits[j].span.start + runningOffset, ts.textSpanEnd(edits[j].span) + runningOffset, edits[j].newText);
                 var change = (edits[j].span.start - ts.textSpanEnd(edits[j].span)) + edits[j].newText.length;
                 runningOffset += change;
@@ -1458,8 +1466,7 @@ module FourSlash {
             }
 
             if (isFormattingEdit) {
-                snapshot = this.languageServiceShimHost.getScriptSnapshot(fileName);
-                var newContent = snapshot.getText(0, snapshot.getLength());
+                var newContent = this.getFileContent(fileName);
 
                 if (newContent.replace(/\s/g, '') !== oldContent.replace(/\s/g, '')) {
                     this.raiseError('Formatting operation destroyed non-whitespace content');
@@ -1506,7 +1513,7 @@ module FourSlash {
         }
 
         public goToEOF() {
-            var len = this.languageServiceShimHost.getScriptSnapshot(this.activeFile.fileName).getLength();
+            var len = this.getFileContent(this.activeFile.fileName).length;
             this.goToPosition(len);
         }
 
@@ -1627,7 +1634,7 @@ module FourSlash {
         public verifyCurrentFileContent(text: string) {
             this.taoInvalidReason = 'verifyCurrentFileContent NYI';
 
-            var actual = this.getCurrentFileContent();
+            var actual = this.getFileContent(this.activeFile.fileName);
             var replaceNewlines = (str: string) => str.replace(/\r\n/g, "\n");
             if (replaceNewlines(actual) !== replaceNewlines(text)) {
                 throw new Error('verifyCurrentFileContent\n' +
@@ -1639,7 +1646,7 @@ module FourSlash {
         public verifyTextAtCaretIs(text: string) {
             this.taoInvalidReason = 'verifyCurrentFileContent NYI';
 
-            var actual = this.languageServiceShimHost.getScriptSnapshot(this.activeFile.fileName).getText(this.currentCaretPosition, this.currentCaretPosition + text.length);
+            var actual = this.getFileContent(this.activeFile.fileName).substring(this.currentCaretPosition, this.currentCaretPosition + text.length);
             if (actual !== text) {
                 throw new Error('verifyTextAtCaretIs\n' +
                     '\tExpected: "' + text + '"\n' +
@@ -1657,7 +1664,7 @@ module FourSlash {
                     '\t  Actual: undefined');
             }
 
-            var actual = this.languageServiceShimHost.getScriptSnapshot(this.activeFile.fileName).getText(span.start, ts.textSpanEnd(span));
+            var actual = this.getFileContent(this.activeFile.fileName).substring(span.start, ts.textSpanEnd(span));
             if (actual !== text) {
                 this.raiseError('verifyCurrentNameOrDottedNameSpanText\n' +
                     '\tExpected: "' + text + '"\n' +
@@ -1731,8 +1738,8 @@ module FourSlash {
 
             function jsonMismatchString() {
                 return ts.sys.newLine +
-                    "expected: '" + ts.sys.newLine + JSON.stringify(expected,(k, v) => v, 2) + "'" + ts.sys.newLine +
-                    "actual:   '" + ts.sys.newLine + JSON.stringify(actual,(k, v) => v, 2) + "'";
+                    "expected: '" + ts.sys.newLine + JSON.stringify(expected, (k, v) => v, 2) + "'" + ts.sys.newLine +
+                    "actual:   '" + ts.sys.newLine + JSON.stringify(actual, (k, v) => v, 2) + "'";
             }
         }
 
@@ -1744,7 +1751,7 @@ module FourSlash {
         }
 
         public verifySyntacticClassifications(expected: { classificationType: string; text: string }[]) {
-            var actual = this.languageService.getSyntacticClassifications(this.activeFile.fileName, 
+            var actual = this.languageService.getSyntacticClassifications(this.activeFile.fileName,
                 ts.createTextSpan(0, this.activeFile.content.length));
 
             this.verifyClassifications(expected, actual);
@@ -1820,69 +1827,6 @@ module FourSlash {
             }
         }
 
-        public verifyTypesAgainstFullCheckAtPositions(positions: number[]) {
-            this.taoInvalidReason = 'verifyTypesAgainstFullCheckAtPositions impossible';
-
-            // Create a from-scratch LS to check against
-            var referenceLanguageServiceShimHost = new Harness.LanguageService.TypeScriptLS();
-            var referenceLanguageServiceShim = referenceLanguageServiceShimHost.getLanguageService();
-            var referenceLanguageService = referenceLanguageServiceShim.languageService;
-
-            // Add lib.d.ts to the reference language service
-            referenceLanguageServiceShimHost.addDefaultLibrary();
-
-            for (var i = 0; i < this.testData.files.length; i++) {
-                var file = this.testData.files[i];
-
-                var snapshot = this.languageServiceShimHost.getScriptSnapshot(file.fileName);
-                var content = snapshot.getText(0, snapshot.getLength());
-                referenceLanguageServiceShimHost.addScript(this.testData.files[i].fileName, content);
-            }
-
-            for (i = 0; i < positions.length; i++) {
-                var nameOf = (type: ts.QuickInfo) => type ? ts.displayPartsToString(type.displayParts) : '(none)';
-
-                var pullName: string, refName: string;
-                var anyFailed = false;
-
-                var errMsg = '';
-
-                try {
-                    var pullType = this.languageService.getQuickInfoAtPosition(this.activeFile.fileName, positions[i]);
-                    pullName = nameOf(pullType);
-                } catch (err1) {
-                    errMsg = 'Failed to get pull type check. Exception: ' + err1 + '\r\n';
-                    if (err1.stack) errMsg = errMsg + err1.stack;
-                    pullName = '(failed)';
-                    anyFailed = true;
-                }
-
-                try {
-                    var referenceType = referenceLanguageService.getQuickInfoAtPosition(this.activeFile.fileName, positions[i]);
-                    refName = nameOf(referenceType);
-                } catch (err2) {
-                    errMsg = 'Failed to get full type check. Exception: ' + err2 + '\r\n';
-                    if (err2.stack) errMsg = errMsg + err2.stack;
-                    refName = '(failed)';
-                    anyFailed = true;
-                }
-
-                var failure = anyFailed || (refName !== pullName);
-                if (failure) {
-                    snapshot = this.languageServiceShimHost.getScriptSnapshot(this.activeFile.fileName);
-                    content = snapshot.getText(0, snapshot.getLength());
-                    var textAtPosition = content.substr(positions[i], 10);
-                    var positionDescription = 'Position ' + positions[i] + ' ("' + textAtPosition + '"...)';
-
-                    if (anyFailed) {
-                        throw new Error('Exception thrown in language service for ' + positionDescription + '\r\n' + errMsg);
-                    } else if (refName !== pullName) {
-                        throw new Error('Pull/Full disagreement failed at ' + positionDescription + ' - expected full typecheck type "' + refName + '" to equal pull type "' + pullName + '".');
-                    }
-                }
-            }
-        }
-
         /*
             Check number of navigationItems which match both searchValue and matchKind.
             Report an error if expected value and actual value do not match.
@@ -2069,12 +2013,11 @@ module FourSlash {
             // The current caret position (in line/col terms)
             var line = this.getCurrentCaretFilePosition().line;
             // The line/col of the start of this line
-            var pos = this.languageServiceShimHost.lineColToPosition(this.activeFile.fileName, line, 1);
+            var pos = this.languageServiceAdapterHost.lineColToPosition(this.activeFile.fileName, line, 1);
             // The index of the current file
 
             // The text from the start of the line to the end of the file
-            var snapshot = this.languageServiceShimHost.getScriptSnapshot(this.activeFile.fileName);
-            var text = snapshot.getText(pos, snapshot.getLength());
+            var text = this.getFileContent(this.activeFile.fileName).substring(pos);
 
             // Truncate to the first newline
             var newlinePos = text.indexOf('\n');
@@ -2089,13 +2032,8 @@ module FourSlash {
             }
         }
 
-        private getCurrentFileContent() {
-            var snapshot = this.languageServiceShimHost.getScriptSnapshot(this.activeFile.fileName);
-            return snapshot.getText(0, snapshot.getLength());
-        }
-
         private getCurrentCaretFilePosition() {
-            var result = this.languageServiceShimHost.positionToZeroBasedLineCol(this.activeFile.fileName, this.currentCaretPosition);
+            var result = this.languageServiceAdapterHost.positionToZeroBasedLineCol(this.activeFile.fileName, this.currentCaretPosition);
             if (result.line >= 0) {
                 result.line++;
             }
@@ -2153,8 +2091,10 @@ module FourSlash {
                 }
             } else if (typeof indexOrName === 'string') {
                 var name = <string>indexOrName;
+
                 // names are stored in the compiler with this relative path, this allows people to use goTo.file on just the fileName
-                name = name.indexOf('/') === -1 ? 'tests/cases/fourslash/' + name : name;
+                name = name.indexOf('/') === -1 ? (this.basePath + '/' + name) : name;
+
                 var availableNames: string[] = [];
                 var foundIt = false;
                 for (var i = 0; i < this.testData.files.length; i++) {
@@ -2180,7 +2120,7 @@ module FourSlash {
         }
 
         private getLineColStringAtPosition(position: number) {
-            var pos = this.languageServiceShimHost.positionToZeroBasedLineCol(this.activeFile.fileName, position);
+            var pos = this.languageServiceAdapterHost.positionToZeroBasedLineCol(this.activeFile.fileName, position);
             return 'line ' + (pos.line + 1) + ', col ' + pos.character;
         }
 
@@ -2206,23 +2146,31 @@ module FourSlash {
                 originalName: ''
             };
         }
+
+        public setCancelled(numberOfCalls: number): void {
+            this.cancellationToken.setCancelled(numberOfCalls)
+        }
+
+        public resetCancelled(): void {
+            this.cancellationToken.resetCancelled();
+        }
     }
 
     // TOOD: should these just use the Harness's stdout/stderr?
     var fsOutput = new Harness.Compiler.WriterAggregator();
     var fsErrors = new Harness.Compiler.WriterAggregator();
     export var xmlData: TestXmlData[] = [];
-    export function runFourSlashTest(fileName: string) {
+    export function runFourSlashTest(basePath: string, testType: FourSlashTestType, fileName: string) {
         var content = Harness.IO.readFile(fileName);
-        var xml = runFourSlashTestContent(content, fileName);
+        var xml = runFourSlashTestContent(basePath, testType, content, fileName);
         xmlData.push(xml);
     }
 
-    export function runFourSlashTestContent(content: string, fileName: string): TestXmlData {
+    export function runFourSlashTestContent(basePath: string, testType: FourSlashTestType, content: string, fileName: string): TestXmlData {
         // Parse out the files and their metadata
-        var testData = parseTestData(content, fileName);
+        var testData = parseTestData(basePath, content, fileName);
 
-        currentTestState = new TestState(testData);
+        currentTestState = new TestState(basePath, testType, testData);
 
         var result = '';
         var host = Harness.Compiler.createCompilerHost([{ unitName: Harness.Compiler.fourslashFileName, content: undefined },
@@ -2265,7 +2213,7 @@ module FourSlash {
         return lines.map(s => s.substr(1)).join('\n');
     }
 
-    function parseTestData(contents: string, fileName: string): FourSlashData {
+    function parseTestData(basePath: string, contents: string, fileName: string): FourSlashData {
         // Regex for parsing options in the format "@Alpha: Value of any sort"
         var optionRegex = /^\s*@(\w+): (.*)\s*/;
 
@@ -2333,7 +2281,7 @@ module FourSlash {
                                 currentFileName = fileName;
                             }
 
-                            currentFileName = 'tests/cases/fourslash/' + match[2];
+                            currentFileName = basePath + '/' + match[2];
                             currentFileOptions[match[1]] = match[2];
                         } else {
                             // Add other fileMetadata flag
diff --git a/src/harness/fourslashRunner.ts b/src/harness/fourslashRunner.ts
index 1ecb02df292..fe3b6c7a91f 100644
--- a/src/harness/fourslashRunner.ts
+++ b/src/harness/fourslashRunner.ts
@@ -2,19 +2,35 @@
 ///<reference path='harness.ts'/>
 ///<reference path='runnerbase.ts' />
 
-class FourslashRunner extends RunnerBase {
-    public basePath = 'tests/cases/fourslash';
+const enum FourSlashTestType { 
+    Native,
+    Shims
+}
 
-    constructor() {
+class FourSlashRunner extends RunnerBase {
+    protected basePath: string;
+    protected testSuiteName: string;
+
+    constructor(private testType: FourSlashTestType) {
         super();
+        switch (testType) {
+            case FourSlashTestType.Native:
+                this.basePath = 'tests/cases/fourslash';
+                this.testSuiteName = 'fourslash';
+                break;
+            case FourSlashTestType.Shims:
+                this.basePath = 'tests/cases/fourslash/shims';
+                this.testSuiteName = 'fourslash-shims';
+                break;
+        }
     }
 
     public initializeTests() {
         if (this.tests.length === 0) {
-            this.tests = this.enumerateFiles(this.basePath, /\.ts/i);
+            this.tests = this.enumerateFiles(this.basePath, /\.ts/i, { recursive: false });
         }
 
-        describe("fourslash tests", () => {
+        describe(this.testSuiteName, () => {
             this.tests.forEach((fn: string) => {
                 fn = ts.normalizeSlashes(fn);
                 var justName = fn.replace(/^.*[\\\/]/, '');
@@ -24,8 +40,8 @@ class FourslashRunner extends RunnerBase {
                 if (testIndex >= 0) fn = fn.substr(testIndex);
 
                 if (justName && !justName.match(/fourslash\.ts$/i) && !justName.match(/\.d\.ts$/i)) {
-                    it('FourSlash test ' + justName + ' runs correctly', function () {
-                        FourSlash.runFourSlashTest(fn);
+                    it(this.testSuiteName + ' test ' + justName + ' runs correctly',() => {
+                        FourSlash.runFourSlashTest(this.basePath, this.testType, fn);
                     });
                 }
             });
@@ -82,9 +98,9 @@ class FourslashRunner extends RunnerBase {
     }
 }
 
-class GeneratedFourslashRunner extends FourslashRunner {
-    constructor() {
-        super();
+class GeneratedFourslashRunner extends FourSlashRunner {
+    constructor(testType: FourSlashTestType) {
+        super(testType);
         this.basePath += '/generated/';
     }
 }
\ No newline at end of file
diff --git a/src/harness/harness.ts b/src/harness/harness.ts
index 5fbf7d976ff..534bf85d119 100644
--- a/src/harness/harness.ts
+++ b/src/harness/harness.ts
@@ -19,6 +19,7 @@
 /// <reference path='external\mocha.d.ts'/>
 /// <reference path='external\chai.d.ts'/>
 /// <reference path='sourceMapRecorder.ts'/>
+/// <reference path='runnerbase.ts'/>
 
 declare var require: any;
 declare var process: any;
@@ -691,8 +692,6 @@ module Harness {
     }
 }
 
-
-
 module Harness {
     var tcServicesFileName = "typescriptServices.js";
 
diff --git a/src/harness/harnessLanguageService.ts b/src/harness/harnessLanguageService.ts
index bf9c75a7167..2f95f5072d0 100644
--- a/src/harness/harnessLanguageService.ts
+++ b/src/harness/harnessLanguageService.ts
@@ -1,5 +1,6 @@
 /// <reference path='..\services\services.ts' />
 /// <reference path='..\services\shims.ts' />
+/// <reference path='harness.ts' />
 
 module Harness.LanguageService {
     export class ScriptInfo {
@@ -54,12 +55,11 @@ module Harness.LanguageService {
         }
     }
 
-    class ScriptSnapshotShim implements ts.ScriptSnapshotShim {
-        private lineMap: number[] = null;
-        private textSnapshot: string;
-        private version: number;
+    class ScriptSnapshot implements ts.IScriptSnapshot {
+        public textSnapshot: string;
+        public version: number;
 
-        constructor(private scriptInfo: ScriptInfo) {
+        constructor(public scriptInfo: ScriptInfo) {
             this.textSnapshot = scriptInfo.content;
             this.version = scriptInfo.version;
         }
@@ -72,9 +72,28 @@ module Harness.LanguageService {
             return this.textSnapshot.length;
         }
 
+        public getChangeRange(oldScript: ts.IScriptSnapshot): ts.TextChangeRange {
+            var oldShim = <ScriptSnapshot>oldScript;
+            return this.scriptInfo.getTextChangeRangeBetweenVersions(oldShim.version, this.version);
+        }
+    }
+
+    class ScriptSnapshotProxy implements ts.ScriptSnapshotShim {
+        constructor(public scriptSnapshot: ts.IScriptSnapshot) {
+        }
+
+        public getText(start: number, end: number): string {
+            return this.scriptSnapshot.getText(start, end);
+        }
+
+        public getLength(): number {
+            return this.scriptSnapshot.getLength();
+        }
+
         public getChangeRange(oldScript: ts.ScriptSnapshotShim): string {
-            var oldShim = <ScriptSnapshotShim>oldScript;
-            var range = this.scriptInfo.getTextChangeRangeBetweenVersions(oldShim.version, this.version);
+            var oldShim = <ScriptSnapshotProxy>oldScript;
+
+            var range = this.scriptSnapshot.getChangeRange(oldShim.scriptSnapshot);
             if (range === null) {
                 return null;
             }
@@ -94,77 +113,38 @@ module Harness.LanguageService {
         }
     }
 
-    export class NonCachingDocumentRegistry implements ts.DocumentRegistry {
-        public static Instance: ts.DocumentRegistry = new NonCachingDocumentRegistry();
-
-        public acquireDocument(
-            fileName: string,
-            compilationSettings: ts.CompilerOptions,
-            scriptSnapshot: ts.IScriptSnapshot,
-            version: string): ts.SourceFile {
-            var sourceFile = Compiler.createSourceFileAndAssertInvariants(fileName, scriptSnapshot.getText(0, scriptSnapshot.getLength()), compilationSettings.target);
-            sourceFile.version = version;
-            return sourceFile;
-        }
-
-        public updateDocument(
-            document: ts.SourceFile,
-            fileName: string,
-            compilationSettings: ts.CompilerOptions,
-            scriptSnapshot: ts.IScriptSnapshot,
-            version: string,
-            textChangeRange: ts.TextChangeRange
-            ): ts.SourceFile {
-            var result = ts.updateLanguageServiceSourceFile(document, scriptSnapshot, version, textChangeRange);
-            Utils.assertInvariants(result, /*parent:*/ undefined);
-            return result;
-        }
-
-        public releaseDocument(fileName: string, compilationSettings: ts.CompilerOptions): void {
-            // no op since this class doesn't cache anything
-        }
+    export interface LanguageServiceAdapter {
+        getHost(): LanguageServiceAdapterHost;
+        getLanguageService(): ts.LanguageService;
+        getClassifier(): ts.Classifier;
+        getPreProcessedFileInfo(fileName: string, fileContents: string): ts.PreProcessedFileInfo;
     }
-    export class TypeScriptLS implements ts.LanguageServiceShimHost {
-        private ls: ts.LanguageServiceShim = null;
 
-        private fileNameToScript: ts.Map<ScriptInfo> = {};
-        private settings: ts.CompilerOptions = {};
-
-        constructor(private cancellationToken: ts.CancellationToken = CancellationToken.None) {
-        }
-
-        public trace(s: string) {
+    export class LanguageServiceAdapterHost  {
+        protected fileNameToScript: ts.Map<ScriptInfo> = {};
+        
+        constructor(protected cancellationToken: ts.CancellationToken = CancellationToken.None,
+            protected settings = ts.getDefaultCompilerOptions()) { 
         }
 
         public getNewLine(): string {
             return "\r\n";
         }
 
-        public addDefaultLibrary() {
-            this.addScript(Harness.Compiler.defaultLibFileName, Harness.Compiler.defaultLibSourceFile.text);
+        public getFilenames(): string[] {
+            var fileNames: string[] = [];
+            ts.forEachKey(this.fileNameToScript,(fileName) => { fileNames.push(fileName); });
+            return fileNames;
         }
 
-        public getHostIdentifier(): string {
-            return "TypeScriptLS";
-        }
-
-        public addFile(fileName: string) {
-            var code = Harness.IO.readFile(fileName);
-            this.addScript(fileName, code);
-        }
-
-        private getScriptInfo(fileName: string): ScriptInfo {
+        public getScriptInfo(fileName: string): ScriptInfo {
             return ts.lookUp(this.fileNameToScript, fileName);
         }
 
-        public addScript(fileName: string, content: string) {
+        public addScript(fileName: string, content: string): void {
             this.fileNameToScript[fileName] = new ScriptInfo(fileName, content);
         }
 
-        private contains(fileName: string): boolean {
-            return ts.hasProperty(this.fileNameToScript, fileName);
-        }
-
         public updateScript(fileName: string, content: string) {
             var script = this.getScriptInfo(fileName);
             if (script !== null) {
@@ -185,107 +165,10 @@ module Harness.LanguageService {
             throw new Error("No script with name '" + fileName + "'");
         }
 
-        //////////////////////////////////////////////////////////////////////
-        // ILogger implementation
-        //
-        public information(): boolean { return false; }
-        public debug(): boolean { return true; }
-        public warning(): boolean { return true; }
-        public error(): boolean { return true; }
-        public fatal(): boolean { return true; }
-
-        public log(s: string): void {
-            // For debugging...
-            //TypeScript.Environment.standardOut.WriteLine("TypeScriptLS:" + s);
-        }
-
-        //////////////////////////////////////////////////////////////////////
-        // LanguageServiceShimHost implementation
-        //
-
-        /// Returns json for Tools.CompilationSettings
-        public getCompilationSettings(): string {
-            return JSON.stringify(this.settings);
-        }
-
-        public getCancellationToken(): ts.CancellationToken {
-            return this.cancellationToken;
-        }
-
-        public getCurrentDirectory(): string {
-            return "";
-        }
-
-        public getDefaultLibFileName(): string {
-            return "";
-        }
-
-        public getScriptFileNames(): string {
-            var fileNames: string[] = [];
-            ts.forEachKey(this.fileNameToScript,(fileName) => { fileNames.push(fileName); });
-            return JSON.stringify(fileNames);
-        }
-
-        public getScriptSnapshot(fileName: string): ts.ScriptSnapshotShim {
-            if (this.contains(fileName)) {
-                return new ScriptSnapshotShim(this.getScriptInfo(fileName));
-            }
-            return undefined;
-        }
-
-        public getScriptVersion(fileName: string): string {
-            if (this.contains(fileName)) {
-                return this.getScriptInfo(fileName).version.toString();
-            }
-            return undefined;
-        }
-
-        public getLocalizedDiagnosticMessages(): string {
-            return JSON.stringify({});
-        }
-
-        /** Return a new instance of the language service shim, up-to-date wrt to typecheck.
-         *  To access the non-shim (i.e. actual) language service, use the "ls.languageService" property.
-         */
-        public getLanguageService(): ts.LanguageServiceShim {
-            this.ls = new TypeScript.Services.TypeScriptServicesFactory().createLanguageServiceShim(this);
-            return this.ls;
-        }
-
-        public setCompilationSettings(settings: ts.CompilerOptions) {
-            for (var key in settings) {
-                if (settings.hasOwnProperty(key)) {
-                    this.settings[key] = settings[key];
-                }
-            }
-        }
-
-        /** Return a new instance of the classifier service shim */
-        public getClassifier(): ts.ClassifierShim {
-            return new TypeScript.Services.TypeScriptServicesFactory().createClassifierShim(this);
-        }
-
-        public getCoreService(): ts.CoreServicesShim {
-            return new TypeScript.Services.TypeScriptServicesFactory().createCoreServicesShim(this);
-        }
-
-        /** Parse file given its source text */
-        public parseSourceText(fileName: string, sourceText: ts.IScriptSnapshot): ts.SourceFile {
-            var result = Compiler.createSourceFileAndAssertInvariants(fileName, sourceText.getText(0, sourceText.getLength()), ts.ScriptTarget.Latest);
-            result.version = "1";
-            return result;
-        }
-
-        /** Parse a file on disk given its fileName */
-        public parseFile(fileName: string) {
-            var sourceText = ts.ScriptSnapshot.fromString(Harness.IO.readFile(fileName));
-            return this.parseSourceText(fileName, sourceText);
-        }
-
         /**
-         * @param line 1 based index
-         * @param col 1 based index
-        */
+          * @param line 1 based index
+          * @param col 1 based index
+          */
         public lineColToPosition(fileName: string, line: number, col: number): number {
             var script: ScriptInfo = this.fileNameToScript[fileName];
             assert.isNotNull(script);
@@ -296,9 +179,9 @@ module Harness.LanguageService {
         }
 
         /**
-         * @param line 0 based index
-         * @param col 0 based index
-        */
+          * @param line 0 based index
+          * @param col 0 based index
+          */
         public positionToZeroBasedLineCol(fileName: string, position: number): ts.LineAndCharacter {
             var script: ScriptInfo = this.fileNameToScript[fileName];
             assert.isNotNull(script);
@@ -309,105 +192,254 @@ module Harness.LanguageService {
             assert.isTrue(result.character >= 1);
             return { line: result.line - 1, character: result.character - 1 };
         }
+    }
 
-        /** Verify that applying edits to sourceFileName result in the content of the file baselineFileName */
-        public checkEdits(sourceFileName: string, baselineFileName: string, edits: ts.TextChange[]) {
-            var script = Harness.IO.readFile(sourceFileName);
-            var formattedScript = this.applyEdits(script, edits);
-            var baseline = Harness.IO.readFile(baselineFileName);
+    /// Native adapter
+    class NativeLanguageServiceHost extends LanguageServiceAdapterHost implements ts.LanguageServiceHost { 
+        getCompilationSettings(): ts.CompilerOptions { return this.settings; }
+        getCancellationToken(): ts.CancellationToken { return this.cancellationToken; }
+        getCurrentDirectory(): string { return ""; }
+        getDefaultLibFileName(): string { return ""; }
+        getScriptFileNames(): string[] { return this.getFilenames(); }
+        getScriptSnapshot(fileName: string): ts.IScriptSnapshot {
+            var script = this.getScriptInfo(fileName);
+            return script ? new ScriptSnapshot(script) : undefined;
+        }
+        getScriptVersion(fileName: string): string {
+            var script = this.getScriptInfo(fileName);
+            return script ? script.version.toString() : undefined;
+        }
+        log(s: string): void { }
+        trace(s: string): void { }
+        error(s: string): void { }
+    }
 
-            function noDiff(text1: string, text2: string) {
-                text1 = text1.replace(/^\s+|\s+$/g, "").replace(/\r\n?/g, "\n");
-                text2 = text2.replace(/^\s+|\s+$/g, "").replace(/\r\n?/g, "\n");
+    export class NativeLanugageServiceAdapter implements LanguageServiceAdapter {
+        private host: NativeLanguageServiceHost;
+        constructor(cancellationToken?: ts.CancellationToken, options?: ts.CompilerOptions) { 
+            this.host = new NativeLanguageServiceHost(cancellationToken, options);
+        }
+        getHost() { return this.host; }
+        getLanguageService(): ts.LanguageService { return ts.createLanguageService(this.host); }
+        getClassifier(): ts.Classifier { return ts.createClassifier(); }
+        getPreProcessedFileInfo(fileName: string, fileContents: string): ts.PreProcessedFileInfo { return ts.preProcessFile(fileContents); }
+    }
 
-                if (text1 !== text2) {
-                    var errorString = "";
-                    var text1Lines = text1.split(/\n/);
-                    var text2Lines = text2.split(/\n/);
-                    for (var i = 0; i < text1Lines.length; i++) {
-                        if (text1Lines[i] !== text2Lines[i]) {
-                            errorString += "Difference at line " + (i + 1) + ":\n";
-                            errorString += "                  Left File: " + text1Lines[i] + "\n";
-                            errorString += "                 Right File: " + text2Lines[i] + "\n\n";
-                        }
-                    }
-                    throw (new Error(errorString));
-                }
-            }
-            assert.isTrue(noDiff(formattedScript, baseline));
-            assert.equal(formattedScript, baseline);
+    /// Shim adapter
+    class ShimLanguageServiceHost extends LanguageServiceAdapterHost implements ts.LanguageServiceShimHost {
+        private nativeHost: NativeLanguageServiceHost;
+        constructor(cancellationToken?: ts.CancellationToken, options?: ts.CompilerOptions) {
+            super(cancellationToken, options);
+            this.nativeHost = new NativeLanguageServiceHost(cancellationToken, options);
         }
 
+        getFilenames(): string[] { return this.nativeHost.getFilenames(); }
+        getScriptInfo(fileName: string): ScriptInfo { return this.nativeHost.getScriptInfo(fileName); }
+        addScript(fileName: string, content: string): void { this.nativeHost.addScript(fileName, content); }
+        updateScript(fileName: string, content: string): void { return this.nativeHost.updateScript(fileName, content); }
+        editScript(fileName: string, minChar: number, limChar: number, newText: string): void { this.nativeHost.editScript(fileName, minChar, limChar, newText); }
+        lineColToPosition(fileName: string, line: number, col: number): number { return this.nativeHost.lineColToPosition(fileName, line, col); }
+        positionToZeroBasedLineCol(fileName: string, position: number): ts.LineAndCharacter { return this.nativeHost.positionToZeroBasedLineCol(fileName, position); }
 
-        /** Apply an array of text edits to a string, and return the resulting string. */
-        public applyEdits(content: string, edits: ts.TextChange[]): string {
-            var result = content;
-            edits = this.normalizeEdits(edits);
-
-            for (var i = edits.length - 1; i >= 0; i--) {
-                var edit = edits[i];
-                var prefix = result.substring(0, edit.span.start);
-                var middle = edit.newText;
-                var suffix = result.substring(ts.textSpanEnd(edit.span));
-                result = prefix + middle + suffix;
-            }
-            return result;
+        getCompilationSettings(): string { return JSON.stringify(this.nativeHost.getCompilationSettings()); }
+        getCancellationToken(): ts.CancellationToken { return this.nativeHost.getCancellationToken(); }
+        getCurrentDirectory(): string { return this.nativeHost.getCurrentDirectory(); }
+        getDefaultLibFileName(): string { return this.nativeHost.getDefaultLibFileName(); }
+        getScriptFileNames(): string { return JSON.stringify(this.nativeHost.getScriptFileNames()); }
+        getScriptSnapshot(fileName: string): ts.ScriptSnapshotShim {
+            var nativeScriptSnapshot = this.nativeHost.getScriptSnapshot(fileName);
+            return nativeScriptSnapshot && new ScriptSnapshotProxy(nativeScriptSnapshot); 
         }
+        getScriptVersion(fileName: string): string { return this.nativeHost.getScriptVersion(fileName); }
+        getLocalizedDiagnosticMessages(): string { return JSON.stringify({}); }
+        log(s: string): void { this.nativeHost.log(s); }
+        trace(s: string): void { this.nativeHost.trace(s); }
+        error(s: string): void { this.nativeHost.error(s); }
+    }
 
-        /** Normalize an array of edits by removing overlapping entries and sorting entries on the minChar position. */
-        private normalizeEdits(edits: ts.TextChange[]): ts.TextChange[] {
-            var result: ts.TextChange[] = [];
+    class ClassifierShimProxy implements ts.Classifier { 
+        constructor(private shim: ts.ClassifierShim) {
+        }
+        getClassificationsForLine(text: string, lexState: ts.EndOfLineState, classifyKeywordsInGenerics?: boolean): ts.ClassificationResult {
+            var result = this.shim.getClassificationsForLine(text, lexState, classifyKeywordsInGenerics).split('\n');
+            var entries: ts.ClassificationInfo[] = [];
+            var i = 0;
+            var position = 0;
 
-            function mapEdits(edits: ts.TextChange[]): { edit: ts.TextChange; index: number; }[] {
-                var result: { edit: ts.TextChange; index: number; }[] = [];
-                for (var i = 0; i < edits.length; i++) {
-                    result.push({ edit: edits[i], index: i });
-                }
-                return result;
+            for (; i < result.length - 1; i += 2) {
+                var t = entries[i / 2] = {
+                    length: parseInt(result[i]),
+                    classification: parseInt(result[i + 1])
+                };
+
+                assert.isTrue(t.length > 0, "Result length should be greater than 0, got :" + t.length);
+                position += t.length;
             }
+            var finalLexState = parseInt(result[result.length - 1]);
 
-            var temp = mapEdits(edits).sort(function (a, b) {
-                var result = a.edit.span.start - b.edit.span.start;
-                if (result === 0)
-                    result = a.index - b.index;
-                return result;
+            assert.equal(position, text.length, "Expected cumulative length of all entries to match the length of the source. expected: " + text.length + ", but got: " + position);
+
+            return {
+                finalLexState,
+                entries
+            };
+        }
+    }
+
+    function unwrapJSONCallResult(result: string): any {
+        var parsedResult = JSON.parse(result);
+        if (parsedResult.error) {
+            throw new Error("Language Service Shim Error: " + JSON.stringify(parsedResult.error));
+        }
+        else if (parsedResult.canceled) { 
+            throw new ts.OperationCanceledException();
+        }
+        return parsedResult.result;
+    }
+
+    class LanguageServiceShimProxy implements ts.LanguageService {
+        constructor(private shim: ts.LanguageServiceShim) {
+        }
+        private unwrappJSONCallResult(result: string): any {
+            var parsedResult = JSON.parse(result);
+            if (parsedResult.error) {
+                throw new Error("Language Service Shim Error: " + JSON.stringify(parsedResult.error));
+            }
+            return parsedResult.result;
+        }
+        cleanupSemanticCache(): void {
+            this.shim.cleanupSemanticCache();
+        }
+        getSyntacticDiagnostics(fileName: string): ts.Diagnostic[] {
+            return unwrapJSONCallResult(this.shim.getSyntacticDiagnostics(fileName));
+        }
+        getSemanticDiagnostics(fileName: string): ts.Diagnostic[] {
+            return unwrapJSONCallResult(this.shim.getSemanticDiagnostics(fileName));
+        }
+        getCompilerOptionsDiagnostics(): ts.Diagnostic[] {
+            return unwrapJSONCallResult(this.shim.getCompilerOptionsDiagnostics());
+        }
+        getSyntacticClassifications(fileName: string, span: ts.TextSpan): ts.ClassifiedSpan[] {
+            return unwrapJSONCallResult(this.shim.getSyntacticClassifications(fileName, span.start, span.length));
+        }
+        getSemanticClassifications(fileName: string, span: ts.TextSpan): ts.ClassifiedSpan[] {
+            return unwrapJSONCallResult(this.shim.getSemanticClassifications(fileName, span.start, span.length));
+        }
+        getCompletionsAtPosition(fileName: string, position: number): ts.CompletionInfo {
+            return unwrapJSONCallResult(this.shim.getCompletionsAtPosition(fileName, position));
+        }
+        getCompletionEntryDetails(fileName: string, position: number, entryName: string): ts.CompletionEntryDetails {
+            return unwrapJSONCallResult(this.shim.getCompletionEntryDetails(fileName, position, entryName));
+        }
+        getQuickInfoAtPosition(fileName: string, position: number): ts.QuickInfo {
+            return unwrapJSONCallResult(this.shim.getQuickInfoAtPosition(fileName, position));
+        }
+        getNameOrDottedNameSpan(fileName: string, startPos: number, endPos: number): ts.TextSpan {
+            return unwrapJSONCallResult(this.shim.getNameOrDottedNameSpan(fileName, startPos, endPos));
+        }
+        getBreakpointStatementAtPosition(fileName: string, position: number): ts.TextSpan {
+            return unwrapJSONCallResult(this.shim.getBreakpointStatementAtPosition(fileName, position));
+        }
+        getSignatureHelpItems(fileName: string, position: number): ts.SignatureHelpItems {
+            return unwrapJSONCallResult(this.shim.getSignatureHelpItems(fileName, position));
+        }
+        getRenameInfo(fileName: string, position: number): ts.RenameInfo {
+            return unwrapJSONCallResult(this.shim.getRenameInfo(fileName, position));
+        }
+        findRenameLocations(fileName: string, position: number, findInStrings: boolean, findInComments: boolean): ts.RenameLocation[] {
+            return unwrapJSONCallResult(this.shim.findRenameLocations(fileName, position, findInStrings, findInComments));
+        }
+        getDefinitionAtPosition(fileName: string, position: number): ts.DefinitionInfo[] {
+            return unwrapJSONCallResult(this.shim.getDefinitionAtPosition(fileName, position));
+        }
+        getReferencesAtPosition(fileName: string, position: number): ts.ReferenceEntry[] {
+            return unwrapJSONCallResult(this.shim.getReferencesAtPosition(fileName, position));
+        }
+        getOccurrencesAtPosition(fileName: string, position: number): ts.ReferenceEntry[] {
+            return unwrapJSONCallResult(this.shim.getOccurrencesAtPosition(fileName, position));
+        }
+        getNavigateToItems(searchValue: string): ts.NavigateToItem[] {
+            return unwrapJSONCallResult(this.shim.getNavigateToItems(searchValue));
+        }
+        getNavigationBarItems(fileName: string): ts.NavigationBarItem[] {
+            return unwrapJSONCallResult(this.shim.getNavigationBarItems(fileName));
+        }
+        getOutliningSpans(fileName: string): ts.OutliningSpan[] {
+            return unwrapJSONCallResult(this.shim.getOutliningSpans(fileName));
+        }
+        getTodoComments(fileName: string, descriptors: ts.TodoCommentDescriptor[]): ts.TodoComment[] {
+            return unwrapJSONCallResult(this.shim.getTodoComments(fileName, JSON.stringify(descriptors)));
+        }
+        getBraceMatchingAtPosition(fileName: string, position: number): ts.TextSpan[] {
+            return unwrapJSONCallResult(this.shim.getBraceMatchingAtPosition(fileName, position));
+        }
+        getIndentationAtPosition(fileName: string, position: number, options: ts.EditorOptions): number {
+            return unwrapJSONCallResult(this.shim.getIndentationAtPosition(fileName, position, JSON.stringify(options)));
+        }
+        getFormattingEditsForRange(fileName: string, start: number, end: number, options: ts.FormatCodeOptions): ts.TextChange[] {
+            return unwrapJSONCallResult(this.shim.getFormattingEditsForRange(fileName, start, end, JSON.stringify(options)));
+        }
+        getFormattingEditsForDocument(fileName: string, options: ts.FormatCodeOptions): ts.TextChange[] {
+            return unwrapJSONCallResult(this.shim.getFormattingEditsForDocument(fileName, JSON.stringify(options)));
+        }
+        getFormattingEditsAfterKeystroke(fileName: string, position: number, key: string, options: ts.FormatCodeOptions): ts.TextChange[] {
+            return unwrapJSONCallResult(this.shim.getFormattingEditsAfterKeystroke(fileName, position, key, JSON.stringify(options)));
+        }
+        getEmitOutput(fileName: string): ts.EmitOutput {
+            return unwrapJSONCallResult(this.shim.getEmitOutput(fileName));
+        }
+        getProgram(): ts.Program {
+            throw new Error("Program can not be marshaled across the shim layer.");
+        }
+        getSourceFile(fileName: string): ts.SourceFile {
+            throw new Error("SourceFile can not be marshaled across the shim layer.");
+        }
+        dispose(): void { this.shim.dispose({}); }
+    }
+
+    export class ShimLanugageServiceAdapter implements LanguageServiceAdapter {
+        private host: ShimLanguageServiceHost;
+        private factory: ts.TypeScriptServicesFactory;
+        constructor(cancellationToken?: ts.CancellationToken, options?: ts.CompilerOptions) {
+            this.host = new ShimLanguageServiceHost(cancellationToken, options);
+            this.factory = new TypeScript.Services.TypeScriptServicesFactory();
+        }
+        getHost() { return this.host; }
+        getLanguageService(): ts.LanguageService { return new LanguageServiceShimProxy(this.factory.createLanguageServiceShim(this.host)); }
+        getClassifier(): ts.Classifier { return new ClassifierShimProxy(this.factory.createClassifierShim(this.host)); }
+        getPreProcessedFileInfo(fileName: string, fileContents: string): ts.PreProcessedFileInfo {
+            var shimResult: {
+                referencedFiles: ts.IFileReference[];
+                importedFiles: ts.IFileReference[];
+                isLibFile: boolean;
+            };
+
+            var coreServicesShim = this.factory.createCoreServicesShim(this.host);
+            shimResult = unwrapJSONCallResult(coreServicesShim.getPreProcessedFileInfo(fileName, ts.ScriptSnapshot.fromString(fileContents)));
+
+            var convertResult: ts.PreProcessedFileInfo = {
+                referencedFiles: [],
+                importedFiles: [],
+                isLibFile: shimResult.isLibFile
+            };
+
+            ts.forEach(shimResult.referencedFiles, refFile => {
+                convertResult.referencedFiles.push({
+                    fileName: refFile.path,
+                    pos: refFile.position,
+                    end: refFile.position + refFile.length
+                });
             });
 
-            var current = 0;
-            var next = 1;
-            while (current < temp.length) {
-                var currentEdit = temp[current].edit;
+            ts.forEach(shimResult.importedFiles, importedFile => {
+                convertResult.importedFiles.push({
+                    fileName: importedFile.path,
+                    pos: importedFile.position,
+                    end: importedFile.position + importedFile.length
+                });
+            });
 
-                // Last edit
-                if (next >= temp.length) {
-                    result.push(currentEdit);
-                    current++;
-                    continue;
-                }
-                var nextEdit = temp[next].edit;
-
-                var gap = nextEdit.span.start - ts.textSpanEnd(currentEdit.span);
-
-                // non-overlapping edits
-                if (gap >= 0) {
-                    result.push(currentEdit);
-                    current = next;
-                    next++;
-                    continue;
-                }
- 
-                // overlapping edits: for now, we only support ignoring an next edit 
-                // entirely contained in the current edit.
-                if (ts.textSpanEnd(currentEdit.span) >= ts.textSpanEnd(nextEdit.span)) {
-                    next++;
-                    continue;
-                }
-                else {
-                    throw new Error("Trying to apply overlapping edits");
-                }
-            }
-
-            return result;
+            return convertResult;
         }
     }
 }
diff --git a/src/harness/runner.ts b/src/harness/runner.ts
index 24349ada3fd..942ae56bf6f 100644
--- a/src/harness/runner.ts
+++ b/src/harness/runner.ts
@@ -61,10 +61,13 @@ if (testConfigFile !== '') {
                 runners.push(new ProjectRunner());
                 break;
             case 'fourslash':
-                runners.push(new FourslashRunner());
+                runners.push(new FourSlashRunner(FourSlashTestType.Native));
+                break;
+            case 'fourslash-shims':
+                runners.push(new FourSlashRunner(FourSlashTestType.Shims));
                 break;
             case 'fourslash-generated':
-                 runners.push(new GeneratedFourslashRunner());
+                runners.push(new GeneratedFourslashRunner(FourSlashTestType.Native));
                 break;
             case 'rwc':
                 runners.push(new RWCRunner());
@@ -90,7 +93,8 @@ if (runners.length === 0) {
     }
 
     // language services
-    runners.push(new FourslashRunner());
+    runners.push(new FourSlashRunner(FourSlashTestType.Native));
+    runners.push(new FourSlashRunner(FourSlashTestType.Shims));
     //runners.push(new GeneratedFourslashRunner());
 }
 
diff --git a/src/services/services.ts b/src/services/services.ts
index 277f574578a..81e8fee42a0 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -1624,31 +1624,14 @@ module ts {
 
     export var disableIncrementalParsing = false;
 
-    export function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange): SourceFile {
-        if (textChangeRange && Debug.shouldAssert(AssertionLevel.Normal)) {
-            var oldText = sourceFile.scriptSnapshot;
-            var newText = scriptSnapshot;
-
-            Debug.assert((oldText.getLength() - textChangeRange.span.length + textChangeRange.newLength) === newText.getLength());
-
-            if (Debug.shouldAssert(AssertionLevel.VeryAggressive)) {
-                var oldTextPrefix = oldText.getText(0, textChangeRange.span.start);
-                var newTextPrefix = newText.getText(0, textChangeRange.span.start);
-                Debug.assert(oldTextPrefix === newTextPrefix);
-
-                var oldTextSuffix = oldText.getText(textSpanEnd(textChangeRange.span), oldText.getLength());
-                var newTextSuffix = newText.getText(textSpanEnd(textChangeRangeNewSpan(textChangeRange)), newText.getLength());
-                Debug.assert(oldTextSuffix === newTextSuffix);
-            }
-        }
-
+    export function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile {
         // If we were given a text change range, and our version or open-ness changed, then 
         // incrementally parse this file.
         if (textChangeRange) {
             if (version !== sourceFile.version) {
                 // Once incremental parsing is ready, then just call into this function.
                 if (!disableIncrementalParsing) {
-                    var newSourceFile = updateSourceFile(sourceFile, scriptSnapshot.getText(0, scriptSnapshot.getLength()), textChangeRange);
+                    var newSourceFile = updateSourceFile(sourceFile, scriptSnapshot.getText(0, scriptSnapshot.getLength()), textChangeRange, aggressiveChecks);
                     setSourceFileFields(newSourceFile, scriptSnapshot, version);
                     // after incremental parsing nameTable might not be up-to-date
                     // drop it so it can be lazily recreated later
@@ -2039,6 +2022,12 @@ module ts {
                 return;
             }
 
+            // IMPORTANT - It is critical from this moment onward that we do not check 
+            // cancellation tokens.  We are about to mutate source files from a previous program
+            // instance.  If we cancel midway through, we may end up in an inconsistent state where
+            // the program points to old source files that have been invalidated because of 
+            // incremental parsing.
+
             var oldSettings = program && program.getCompilerOptions();
             var newSettings = hostCache.compilationSettings();
             var changesInCompilationSettingsAffectSyntax = oldSettings && oldSettings.target !== newSettings.target;
@@ -2073,8 +2062,6 @@ module ts {
             return;
 
             function getOrCreateSourceFile(fileName: string): SourceFile {
-                cancellationToken.throwIfCancellationRequested();
-
                 // The program is asking for this file, check first if the host can locate it.
                 // If the host can not locate the file, then it does not exist. return undefined
                 // to the program to allow reporting of errors for missing files.
@@ -5380,9 +5367,6 @@ module ts {
             cancellationToken.throwIfCancellationRequested();
 
             var fileContents = sourceFile.text;
-
-            cancellationToken.throwIfCancellationRequested();
-
             var result: TodoComment[] = [];
 
             if (descriptors.length > 0) {
diff --git a/src/services/shims.ts b/src/services/shims.ts
index 759c1078d90..0f9f1a12cd1 100644
--- a/src/services/shims.ts
+++ b/src/services/shims.ts
@@ -90,6 +90,7 @@ module ts {
         getCompilerOptionsDiagnostics(): string;
 
         getSyntacticClassifications(fileName: string, start: number, length: number): string;
+        getSemanticClassifications(fileName: string, start: number, length: number): string;
 
         getCompletionsAtPosition(fileName: string, position: number): string;
         getCompletionEntryDetails(fileName: string, position: number, entryName: string): string;
diff --git a/tests/baselines/reference/APISample_compile.js b/tests/baselines/reference/APISample_compile.js
index aaa7ad596e5..9704b2ecd49 100644
--- a/tests/baselines/reference/APISample_compile.js
+++ b/tests/baselines/reference/APISample_compile.js
@@ -1406,7 +1406,7 @@ declare module "typescript" {
     function createNode(kind: SyntaxKind): Node;
     function forEachChild<T>(node: Node, cbNode: (node: Node) => T, cbNodeArray?: (nodes: Node[]) => T): T;
     function modifierToFlag(token: SyntaxKind): NodeFlags;
-    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange): SourceFile;
+    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;
     function isEvalOrArgumentsIdentifier(node: Node): boolean;
     function createSourceFile(fileName: string, sourceText: string, languageVersion: ScriptTarget, setParentNodes?: boolean): SourceFile;
     function isLeftHandSideExpression(expr: Expression): boolean;
@@ -1897,7 +1897,7 @@ declare module "typescript" {
     }
     function createLanguageServiceSourceFile(fileName: string, scriptSnapshot: IScriptSnapshot, scriptTarget: ScriptTarget, version: string, setNodeParents: boolean): SourceFile;
     var disableIncrementalParsing: boolean;
-    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange): SourceFile;
+    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;
     function createDocumentRegistry(): DocumentRegistry;
     function preProcessFile(sourceText: string, readImportFiles?: boolean): PreProcessedFileInfo;
     function createLanguageService(host: LanguageServiceHost, documentRegistry?: DocumentRegistry): LanguageService;
diff --git a/tests/baselines/reference/APISample_compile.types b/tests/baselines/reference/APISample_compile.types
index 44f42085807..6b9c83d3954 100644
--- a/tests/baselines/reference/APISample_compile.types
+++ b/tests/baselines/reference/APISample_compile.types
@@ -4490,13 +4490,14 @@ declare module "typescript" {
 >SyntaxKind : SyntaxKind
 >NodeFlags : NodeFlags
 
-    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange): SourceFile;

->updateSourceFile : (sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange) => SourceFile
+    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;

+>updateSourceFile : (sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean) => SourceFile
 >sourceFile : SourceFile
 >SourceFile : SourceFile
 >newText : string
 >textChangeRange : TextChangeRange
 >TextChangeRange : TextChangeRange
+>aggressiveChecks : boolean
 >SourceFile : SourceFile
 
     function isEvalOrArgumentsIdentifier(node: Node): boolean;

@@ -5901,8 +5902,8 @@ declare module "typescript" {
     var disableIncrementalParsing: boolean;

 >disableIncrementalParsing : boolean
 
-    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange): SourceFile;

->updateLanguageServiceSourceFile : (sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange) => SourceFile
+    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;

+>updateLanguageServiceSourceFile : (sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean) => SourceFile
 >sourceFile : SourceFile
 >SourceFile : SourceFile
 >scriptSnapshot : IScriptSnapshot
@@ -5910,6 +5911,7 @@ declare module "typescript" {
 >version : string
 >textChangeRange : TextChangeRange
 >TextChangeRange : TextChangeRange
+>aggressiveChecks : boolean
 >SourceFile : SourceFile
 
     function createDocumentRegistry(): DocumentRegistry;

diff --git a/tests/baselines/reference/APISample_linter.js b/tests/baselines/reference/APISample_linter.js
index 629be085c3a..48cb0ec6c9d 100644
--- a/tests/baselines/reference/APISample_linter.js
+++ b/tests/baselines/reference/APISample_linter.js
@@ -1437,7 +1437,7 @@ declare module "typescript" {
     function createNode(kind: SyntaxKind): Node;
     function forEachChild<T>(node: Node, cbNode: (node: Node) => T, cbNodeArray?: (nodes: Node[]) => T): T;
     function modifierToFlag(token: SyntaxKind): NodeFlags;
-    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange): SourceFile;
+    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;
     function isEvalOrArgumentsIdentifier(node: Node): boolean;
     function createSourceFile(fileName: string, sourceText: string, languageVersion: ScriptTarget, setParentNodes?: boolean): SourceFile;
     function isLeftHandSideExpression(expr: Expression): boolean;
@@ -1928,7 +1928,7 @@ declare module "typescript" {
     }
     function createLanguageServiceSourceFile(fileName: string, scriptSnapshot: IScriptSnapshot, scriptTarget: ScriptTarget, version: string, setNodeParents: boolean): SourceFile;
     var disableIncrementalParsing: boolean;
-    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange): SourceFile;
+    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;
     function createDocumentRegistry(): DocumentRegistry;
     function preProcessFile(sourceText: string, readImportFiles?: boolean): PreProcessedFileInfo;
     function createLanguageService(host: LanguageServiceHost, documentRegistry?: DocumentRegistry): LanguageService;
diff --git a/tests/baselines/reference/APISample_linter.types b/tests/baselines/reference/APISample_linter.types
index 8f3a90c35d1..835185c2d53 100644
--- a/tests/baselines/reference/APISample_linter.types
+++ b/tests/baselines/reference/APISample_linter.types
@@ -4634,13 +4634,14 @@ declare module "typescript" {
 >SyntaxKind : SyntaxKind
 >NodeFlags : NodeFlags
 
-    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange): SourceFile;

->updateSourceFile : (sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange) => SourceFile
+    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;

+>updateSourceFile : (sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean) => SourceFile
 >sourceFile : SourceFile
 >SourceFile : SourceFile
 >newText : string
 >textChangeRange : TextChangeRange
 >TextChangeRange : TextChangeRange
+>aggressiveChecks : boolean
 >SourceFile : SourceFile
 
     function isEvalOrArgumentsIdentifier(node: Node): boolean;

@@ -6045,8 +6046,8 @@ declare module "typescript" {
     var disableIncrementalParsing: boolean;

 >disableIncrementalParsing : boolean
 
-    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange): SourceFile;

->updateLanguageServiceSourceFile : (sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange) => SourceFile
+    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;

+>updateLanguageServiceSourceFile : (sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean) => SourceFile
 >sourceFile : SourceFile
 >SourceFile : SourceFile
 >scriptSnapshot : IScriptSnapshot
@@ -6054,6 +6055,7 @@ declare module "typescript" {
 >version : string
 >textChangeRange : TextChangeRange
 >TextChangeRange : TextChangeRange
+>aggressiveChecks : boolean
 >SourceFile : SourceFile
 
     function createDocumentRegistry(): DocumentRegistry;

diff --git a/tests/baselines/reference/APISample_transform.js b/tests/baselines/reference/APISample_transform.js
index 66b0182728d..584368e8cb6 100644
--- a/tests/baselines/reference/APISample_transform.js
+++ b/tests/baselines/reference/APISample_transform.js
@@ -1438,7 +1438,7 @@ declare module "typescript" {
     function createNode(kind: SyntaxKind): Node;
     function forEachChild<T>(node: Node, cbNode: (node: Node) => T, cbNodeArray?: (nodes: Node[]) => T): T;
     function modifierToFlag(token: SyntaxKind): NodeFlags;
-    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange): SourceFile;
+    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;
     function isEvalOrArgumentsIdentifier(node: Node): boolean;
     function createSourceFile(fileName: string, sourceText: string, languageVersion: ScriptTarget, setParentNodes?: boolean): SourceFile;
     function isLeftHandSideExpression(expr: Expression): boolean;
@@ -1929,7 +1929,7 @@ declare module "typescript" {
     }
     function createLanguageServiceSourceFile(fileName: string, scriptSnapshot: IScriptSnapshot, scriptTarget: ScriptTarget, version: string, setNodeParents: boolean): SourceFile;
     var disableIncrementalParsing: boolean;
-    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange): SourceFile;
+    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;
     function createDocumentRegistry(): DocumentRegistry;
     function preProcessFile(sourceText: string, readImportFiles?: boolean): PreProcessedFileInfo;
     function createLanguageService(host: LanguageServiceHost, documentRegistry?: DocumentRegistry): LanguageService;
diff --git a/tests/baselines/reference/APISample_transform.types b/tests/baselines/reference/APISample_transform.types
index c8d2ec5bed3..e64d201f1b0 100644
--- a/tests/baselines/reference/APISample_transform.types
+++ b/tests/baselines/reference/APISample_transform.types
@@ -4586,13 +4586,14 @@ declare module "typescript" {
 >SyntaxKind : SyntaxKind
 >NodeFlags : NodeFlags
 
-    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange): SourceFile;

->updateSourceFile : (sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange) => SourceFile
+    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;

+>updateSourceFile : (sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean) => SourceFile
 >sourceFile : SourceFile
 >SourceFile : SourceFile
 >newText : string
 >textChangeRange : TextChangeRange
 >TextChangeRange : TextChangeRange
+>aggressiveChecks : boolean
 >SourceFile : SourceFile
 
     function isEvalOrArgumentsIdentifier(node: Node): boolean;

@@ -5997,8 +5998,8 @@ declare module "typescript" {
     var disableIncrementalParsing: boolean;

 >disableIncrementalParsing : boolean
 
-    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange): SourceFile;

->updateLanguageServiceSourceFile : (sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange) => SourceFile
+    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;

+>updateLanguageServiceSourceFile : (sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean) => SourceFile
 >sourceFile : SourceFile
 >SourceFile : SourceFile
 >scriptSnapshot : IScriptSnapshot
@@ -6006,6 +6007,7 @@ declare module "typescript" {
 >version : string
 >textChangeRange : TextChangeRange
 >TextChangeRange : TextChangeRange
+>aggressiveChecks : boolean
 >SourceFile : SourceFile
 
     function createDocumentRegistry(): DocumentRegistry;

diff --git a/tests/baselines/reference/APISample_watcher.js b/tests/baselines/reference/APISample_watcher.js
index 93bb9b16afb..3e144124847 100644
--- a/tests/baselines/reference/APISample_watcher.js
+++ b/tests/baselines/reference/APISample_watcher.js
@@ -1475,7 +1475,7 @@ declare module "typescript" {
     function createNode(kind: SyntaxKind): Node;
     function forEachChild<T>(node: Node, cbNode: (node: Node) => T, cbNodeArray?: (nodes: Node[]) => T): T;
     function modifierToFlag(token: SyntaxKind): NodeFlags;
-    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange): SourceFile;
+    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;
     function isEvalOrArgumentsIdentifier(node: Node): boolean;
     function createSourceFile(fileName: string, sourceText: string, languageVersion: ScriptTarget, setParentNodes?: boolean): SourceFile;
     function isLeftHandSideExpression(expr: Expression): boolean;
@@ -1966,7 +1966,7 @@ declare module "typescript" {
     }
     function createLanguageServiceSourceFile(fileName: string, scriptSnapshot: IScriptSnapshot, scriptTarget: ScriptTarget, version: string, setNodeParents: boolean): SourceFile;
     var disableIncrementalParsing: boolean;
-    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange): SourceFile;
+    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;
     function createDocumentRegistry(): DocumentRegistry;
     function preProcessFile(sourceText: string, readImportFiles?: boolean): PreProcessedFileInfo;
     function createLanguageService(host: LanguageServiceHost, documentRegistry?: DocumentRegistry): LanguageService;
diff --git a/tests/baselines/reference/APISample_watcher.types b/tests/baselines/reference/APISample_watcher.types
index 27acbb0a726..faed2c422f9 100644
--- a/tests/baselines/reference/APISample_watcher.types
+++ b/tests/baselines/reference/APISample_watcher.types
@@ -4759,13 +4759,14 @@ declare module "typescript" {
 >SyntaxKind : SyntaxKind
 >NodeFlags : NodeFlags
 
-    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange): SourceFile;

->updateSourceFile : (sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange) => SourceFile
+    function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;

+>updateSourceFile : (sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean) => SourceFile
 >sourceFile : SourceFile
 >SourceFile : SourceFile
 >newText : string
 >textChangeRange : TextChangeRange
 >TextChangeRange : TextChangeRange
+>aggressiveChecks : boolean
 >SourceFile : SourceFile
 
     function isEvalOrArgumentsIdentifier(node: Node): boolean;

@@ -6170,8 +6171,8 @@ declare module "typescript" {
     var disableIncrementalParsing: boolean;

 >disableIncrementalParsing : boolean
 
-    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange): SourceFile;

->updateLanguageServiceSourceFile : (sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange) => SourceFile
+    function updateLanguageServiceSourceFile(sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile;

+>updateLanguageServiceSourceFile : (sourceFile: SourceFile, scriptSnapshot: IScriptSnapshot, version: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean) => SourceFile
 >sourceFile : SourceFile
 >SourceFile : SourceFile
 >scriptSnapshot : IScriptSnapshot
@@ -6179,6 +6180,7 @@ declare module "typescript" {
 >version : string
 >textChangeRange : TextChangeRange
 >TextChangeRange : TextChangeRange
+>aggressiveChecks : boolean
 >SourceFile : SourceFile
 
     function createDocumentRegistry(): DocumentRegistry;

diff --git a/tests/baselines/reference/callWithSpread.errors.txt b/tests/baselines/reference/callWithSpread.errors.txt
new file mode 100644
index 00000000000..a28d4c8b1a1
--- /dev/null
+++ b/tests/baselines/reference/callWithSpread.errors.txt
@@ -0,0 +1,59 @@
+tests/cases/conformance/expressions/functionCalls/callWithSpread.ts(52,21): error TS2472: Spread operator in 'new' expressions is only available when targeting ECMAScript 6 and higher.
+
+
+==== tests/cases/conformance/expressions/functionCalls/callWithSpread.ts (1 errors) ====
+    interface X {
+        foo(x: number, y: number, ...z: string[]);
+    }
+    
+    function foo(x: number, y: number, ...z: string[]) {
+    }
+    
+    var a: string[];
+    var z: number[];
+    var obj: X;
+    var xa: X[];
+    
+    foo(1, 2, "abc");
+    foo(1, 2, ...a);
+    foo(1, 2, ...a, "abc");
+    
+    obj.foo(1, 2, "abc");
+    obj.foo(1, 2, ...a);
+    obj.foo(1, 2, ...a, "abc");
+    
+    (obj.foo)(1, 2, "abc");
+    (obj.foo)(1, 2, ...a);
+    (obj.foo)(1, 2, ...a, "abc");
+    
+    xa[1].foo(1, 2, "abc");
+    xa[1].foo(1, 2, ...a);
+    xa[1].foo(1, 2, ...a, "abc");
+    
+    (<Function>xa[1].foo)(...[1, 2, "abc"]);
+    
+    class C {
+        constructor(x: number, y: number, ...z: string[]) {
+            this.foo(x, y);
+            this.foo(x, y, ...z);
+        }
+        foo(x: number, y: number, ...z: string[]) {
+        }
+    }
+    
+    class D extends C {
+        constructor() {
+            super(1, 2);
+            super(1, 2, ...a);
+        }
+        foo() {
+            super.foo(1, 2);
+            super.foo(1, 2, ...a);
+        }
+    }
+    
+    // Only supported in when target is ES6
+    var c = new C(1, 2, ...a);
+                        ~~~~
+!!! error TS2472: Spread operator in 'new' expressions is only available when targeting ECMAScript 6 and higher.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/callWithSpread.js b/tests/baselines/reference/callWithSpread.js
new file mode 100644
index 00000000000..d676c0f2a33
--- /dev/null
+++ b/tests/baselines/reference/callWithSpread.js
@@ -0,0 +1,117 @@
+//// [callWithSpread.ts]
+interface X {
+    foo(x: number, y: number, ...z: string[]);
+}
+
+function foo(x: number, y: number, ...z: string[]) {
+}
+
+var a: string[];
+var z: number[];
+var obj: X;
+var xa: X[];
+
+foo(1, 2, "abc");
+foo(1, 2, ...a);
+foo(1, 2, ...a, "abc");
+
+obj.foo(1, 2, "abc");
+obj.foo(1, 2, ...a);
+obj.foo(1, 2, ...a, "abc");
+
+(obj.foo)(1, 2, "abc");
+(obj.foo)(1, 2, ...a);
+(obj.foo)(1, 2, ...a, "abc");
+
+xa[1].foo(1, 2, "abc");
+xa[1].foo(1, 2, ...a);
+xa[1].foo(1, 2, ...a, "abc");
+
+(<Function>xa[1].foo)(...[1, 2, "abc"]);
+
+class C {
+    constructor(x: number, y: number, ...z: string[]) {
+        this.foo(x, y);
+        this.foo(x, y, ...z);
+    }
+    foo(x: number, y: number, ...z: string[]) {
+    }
+}
+
+class D extends C {
+    constructor() {
+        super(1, 2);
+        super(1, 2, ...a);
+    }
+    foo() {
+        super.foo(1, 2);
+        super.foo(1, 2, ...a);
+    }
+}
+
+// Only supported in when target is ES6
+var c = new C(1, 2, ...a);
+
+
+//// [callWithSpread.js]
+var __extends = this.__extends || function (d, b) {
+    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
+    function __() { this.constructor = d; }
+    __.prototype = b.prototype;
+    d.prototype = new __();
+};
+function foo(x, y) {
+    var z = [];
+    for (var _i = 2; _i < arguments.length; _i++) {
+        z[_i - 2] = arguments[_i];
+    }
+}
+var a;
+var z;
+var obj;
+var xa;
+foo(1, 2, "abc");
+foo.apply(void 0, [1, 2].concat(a));
+foo.apply(void 0, [1, 2].concat(a, ["abc"]));
+obj.foo(1, 2, "abc");
+obj.foo.apply(obj, [1, 2].concat(a));
+obj.foo.apply(obj, [1, 2].concat(a, ["abc"]));
+(obj.foo)(1, 2, "abc");
+obj.foo.apply(obj, [1, 2].concat(a));
+obj.foo.apply(obj, [1, 2].concat(a, ["abc"]));
+xa[1].foo(1, 2, "abc");
+(_a = xa[1]).foo.apply(_a, [1, 2].concat(a));
+(_b = xa[1]).foo.apply(_b, [1, 2].concat(a, ["abc"]));
+(_c = xa[1]).foo.apply(_c, [1, 2, "abc"]);
+var C = (function () {
+    function C(x, y) {
+        var z = [];
+        for (var _i = 2; _i < arguments.length; _i++) {
+            z[_i - 2] = arguments[_i];
+        }
+        this.foo(x, y);
+        this.foo.apply(this, [x, y].concat(z));
+    }
+    C.prototype.foo = function (x, y) {
+        var z = [];
+        for (var _i = 2; _i < arguments.length; _i++) {
+            z[_i - 2] = arguments[_i];
+        }
+    };
+    return C;
+})();
+var D = (function (_super) {
+    __extends(D, _super);
+    function D() {
+        _super.call(this, 1, 2);
+        _super.apply(this, [1, 2].concat(a));
+    }
+    D.prototype.foo = function () {
+        _super.prototype.foo.call(this, 1, 2);
+        _super.prototype.foo.apply(this, [1, 2].concat(a));
+    };
+    return D;
+})(C);
+// Only supported in when target is ES6
+var c = new C(1, 2, ...a);
+var _a, _b, _c;
diff --git a/tests/baselines/reference/callWithSpreadES6.js b/tests/baselines/reference/callWithSpreadES6.js
new file mode 100644
index 00000000000..bdb5aab33ec
--- /dev/null
+++ b/tests/baselines/reference/callWithSpreadES6.js
@@ -0,0 +1,105 @@
+//// [callWithSpreadES6.ts]
+
+interface X {
+    foo(x: number, y: number, ...z: string[]);
+}
+
+function foo(x: number, y: number, ...z: string[]) {
+}
+
+var a: string[];
+var z: number[];
+var obj: X;
+var xa: X[];
+
+foo(1, 2, "abc");
+foo(1, 2, ...a);
+foo(1, 2, ...a, "abc");
+
+obj.foo(1, 2, "abc");
+obj.foo(1, 2, ...a);
+obj.foo(1, 2, ...a, "abc");
+
+(obj.foo)(1, 2, "abc");
+(obj.foo)(1, 2, ...a);
+(obj.foo)(1, 2, ...a, "abc");
+
+xa[1].foo(1, 2, "abc");
+xa[1].foo(1, 2, ...a);
+xa[1].foo(1, 2, ...a, "abc");
+
+(<Function>xa[1].foo)(...[1, 2, "abc"]);
+
+class C {
+    constructor(x: number, y: number, ...z: string[]) {
+        this.foo(x, y);
+        this.foo(x, y, ...z);
+    }
+    foo(x: number, y: number, ...z: string[]) {
+    }
+}
+
+class D extends C {
+    constructor() {
+        super(1, 2);
+        super(1, 2, ...a);
+    }
+    foo() {
+        super.foo(1, 2);
+        super.foo(1, 2, ...a);
+    }
+}
+
+// Only supported in when target is ES6
+var c = new C(1, 2, ...a);
+
+
+//// [callWithSpreadES6.js]
+var __extends = this.__extends || function (d, b) {
+    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
+    function __() { this.constructor = d; }
+    __.prototype = b.prototype;
+    d.prototype = new __();
+};
+function foo(x, y, ...z) {
+}
+var a;
+var z;
+var obj;
+var xa;
+foo(1, 2, "abc");
+foo(1, 2, ...a);
+foo(1, 2, ...a, "abc");
+obj.foo(1, 2, "abc");
+obj.foo(1, 2, ...a);
+obj.foo(1, 2, ...a, "abc");
+(obj.foo)(1, 2, "abc");
+(obj.foo)(1, 2, ...a);
+(obj.foo)(1, 2, ...a, "abc");
+xa[1].foo(1, 2, "abc");
+xa[1].foo(1, 2, ...a);
+xa[1].foo(1, 2, ...a, "abc");
+xa[1].foo(...[1, 2, "abc"]);
+var C = (function () {
+    function C(x, y, ...z) {
+        this.foo(x, y);
+        this.foo(x, y, ...z);
+    }
+    C.prototype.foo = function (x, y, ...z) {
+    };
+    return C;
+})();
+var D = (function (_super) {
+    __extends(D, _super);
+    function D() {
+        _super.call(this, 1, 2);
+        _super.call(this, 1, 2, ...a);
+    }
+    D.prototype.foo = function () {
+        _super.prototype.foo.call(this, 1, 2);
+        _super.prototype.foo.call(this, 1, 2, ...a);
+    };
+    return D;
+})(C);
+// Only supported in when target is ES6
+var c = new C(1, 2, ...a);
diff --git a/tests/baselines/reference/callWithSpreadES6.types b/tests/baselines/reference/callWithSpreadES6.types
new file mode 100644
index 00000000000..8a75d21e4ef
--- /dev/null
+++ b/tests/baselines/reference/callWithSpreadES6.types
@@ -0,0 +1,196 @@
+=== tests/cases/conformance/expressions/functionCalls/callWithSpreadES6.ts ===
+
+interface X {
+>X : X
+
+    foo(x: number, y: number, ...z: string[]);
+>foo : (x: number, y: number, ...z: string[]) => any
+>x : number
+>y : number
+>z : string[]
+}
+
+function foo(x: number, y: number, ...z: string[]) {
+>foo : (x: number, y: number, ...z: string[]) => void
+>x : number
+>y : number
+>z : string[]
+}
+
+var a: string[];
+>a : string[]
+
+var z: number[];
+>z : number[]
+
+var obj: X;
+>obj : X
+>X : X
+
+var xa: X[];
+>xa : X[]
+>X : X
+
+foo(1, 2, "abc");
+>foo(1, 2, "abc") : void
+>foo : (x: number, y: number, ...z: string[]) => void
+
+foo(1, 2, ...a);
+>foo(1, 2, ...a) : void
+>foo : (x: number, y: number, ...z: string[]) => void
+>a : string[]
+
+foo(1, 2, ...a, "abc");
+>foo(1, 2, ...a, "abc") : void
+>foo : (x: number, y: number, ...z: string[]) => void
+>a : string[]
+
+obj.foo(1, 2, "abc");
+>obj.foo(1, 2, "abc") : any
+>obj.foo : (x: number, y: number, ...z: string[]) => any
+>obj : X
+>foo : (x: number, y: number, ...z: string[]) => any
+
+obj.foo(1, 2, ...a);
+>obj.foo(1, 2, ...a) : any
+>obj.foo : (x: number, y: number, ...z: string[]) => any
+>obj : X
+>foo : (x: number, y: number, ...z: string[]) => any
+>a : string[]
+
+obj.foo(1, 2, ...a, "abc");
+>obj.foo(1, 2, ...a, "abc") : any
+>obj.foo : (x: number, y: number, ...z: string[]) => any
+>obj : X
+>foo : (x: number, y: number, ...z: string[]) => any
+>a : string[]
+
+(obj.foo)(1, 2, "abc");
+>(obj.foo)(1, 2, "abc") : any
+>(obj.foo) : (x: number, y: number, ...z: string[]) => any
+>obj.foo : (x: number, y: number, ...z: string[]) => any
+>obj : X
+>foo : (x: number, y: number, ...z: string[]) => any
+
+(obj.foo)(1, 2, ...a);
+>(obj.foo)(1, 2, ...a) : any
+>(obj.foo) : (x: number, y: number, ...z: string[]) => any
+>obj.foo : (x: number, y: number, ...z: string[]) => any
+>obj : X
+>foo : (x: number, y: number, ...z: string[]) => any
+>a : string[]
+
+(obj.foo)(1, 2, ...a, "abc");
+>(obj.foo)(1, 2, ...a, "abc") : any
+>(obj.foo) : (x: number, y: number, ...z: string[]) => any
+>obj.foo : (x: number, y: number, ...z: string[]) => any
+>obj : X
+>foo : (x: number, y: number, ...z: string[]) => any
+>a : string[]
+
+xa[1].foo(1, 2, "abc");
+>xa[1].foo(1, 2, "abc") : any
+>xa[1].foo : (x: number, y: number, ...z: string[]) => any
+>xa[1] : X
+>xa : X[]
+>foo : (x: number, y: number, ...z: string[]) => any
+
+xa[1].foo(1, 2, ...a);
+>xa[1].foo(1, 2, ...a) : any
+>xa[1].foo : (x: number, y: number, ...z: string[]) => any
+>xa[1] : X
+>xa : X[]
+>foo : (x: number, y: number, ...z: string[]) => any
+>a : string[]
+
+xa[1].foo(1, 2, ...a, "abc");
+>xa[1].foo(1, 2, ...a, "abc") : any
+>xa[1].foo : (x: number, y: number, ...z: string[]) => any
+>xa[1] : X
+>xa : X[]
+>foo : (x: number, y: number, ...z: string[]) => any
+>a : string[]
+
+(<Function>xa[1].foo)(...[1, 2, "abc"]);
+>(<Function>xa[1].foo)(...[1, 2, "abc"]) : any
+>(<Function>xa[1].foo) : Function
+><Function>xa[1].foo : Function
+>Function : Function
+>xa[1].foo : (x: number, y: number, ...z: string[]) => any
+>xa[1] : X
+>xa : X[]
+>foo : (x: number, y: number, ...z: string[]) => any
+>[1, 2, "abc"] : (string | number)[]
+
+class C {
+>C : C
+
+    constructor(x: number, y: number, ...z: string[]) {
+>x : number
+>y : number
+>z : string[]
+
+        this.foo(x, y);
+>this.foo(x, y) : void
+>this.foo : (x: number, y: number, ...z: string[]) => void
+>this : C
+>foo : (x: number, y: number, ...z: string[]) => void
+>x : number
+>y : number
+
+        this.foo(x, y, ...z);
+>this.foo(x, y, ...z) : void
+>this.foo : (x: number, y: number, ...z: string[]) => void
+>this : C
+>foo : (x: number, y: number, ...z: string[]) => void
+>x : number
+>y : number
+>z : string[]
+    }
+    foo(x: number, y: number, ...z: string[]) {
+>foo : (x: number, y: number, ...z: string[]) => void
+>x : number
+>y : number
+>z : string[]
+    }
+}
+
+class D extends C {
+>D : D
+>C : C
+
+    constructor() {
+        super(1, 2);
+>super(1, 2) : void
+>super : typeof C
+
+        super(1, 2, ...a);
+>super(1, 2, ...a) : void
+>super : typeof C
+>a : string[]
+    }
+    foo() {
+>foo : () => void
+
+        super.foo(1, 2);
+>super.foo(1, 2) : void
+>super.foo : (x: number, y: number, ...z: string[]) => void
+>super : C
+>foo : (x: number, y: number, ...z: string[]) => void
+
+        super.foo(1, 2, ...a);
+>super.foo(1, 2, ...a) : void
+>super.foo : (x: number, y: number, ...z: string[]) => void
+>super : C
+>foo : (x: number, y: number, ...z: string[]) => void
+>a : string[]
+    }
+}
+
+// Only supported in when target is ES6
+var c = new C(1, 2, ...a);
+>c : C
+>new C(1, 2, ...a) : C
+>C : typeof C
+>a : string[]
+
diff --git a/tests/baselines/reference/getBreakpointStatementAtPosition.baseline b/tests/baselines/reference/getBreakpointStatementAtPosition.baseline
new file mode 100644
index 00000000000..617589b9047
--- /dev/null
+++ b/tests/baselines/reference/getBreakpointStatementAtPosition.baseline
@@ -0,0 +1,71 @@
+
+1  >while (true) {
+
+    ~~~~~~~~~~~~~~~                               => Pos: (0 to 14)  SpanInfo: {"start":0,"length":12}
+    >while (true)
+    >:=> (line 1, col 0) to (line 1, col 12)
+--------------------------------
+2  >    break;
+
+    ~~~~~~~~~~~                                   => Pos: (15 to 25)  SpanInfo: {"start":19,"length":5}
+    >break
+    >:=> (line 2, col 4) to (line 2, col 9)
+--------------------------------
+3  >}
+
+    ~~                                            => Pos: (26 to 27)  SpanInfo: {"start":19,"length":5}
+    >break
+    >:=> (line 2, col 4) to (line 2, col 9)
+--------------------------------
+4  >y: while (true) {
+
+    ~~~~~~~~~~~~~~~~~~                            => Pos: (28 to 45)  SpanInfo: {"start":31,"length":12}
+    >while (true)
+    >:=> (line 4, col 3) to (line 4, col 15)
+--------------------------------
+5  >    break y;
+
+    ~~~~~~~~~~~~~                                 => Pos: (46 to 58)  SpanInfo: {"start":50,"length":7}
+    >break y
+    >:=> (line 5, col 4) to (line 5, col 11)
+--------------------------------
+6  >}
+
+    ~~                                            => Pos: (59 to 60)  SpanInfo: {"start":50,"length":7}
+    >break y
+    >:=> (line 5, col 4) to (line 5, col 11)
+--------------------------------
+7  >while (true) {
+
+    ~~~~~~~~~~~~~~~                               => Pos: (61 to 75)  SpanInfo: {"start":61,"length":12}
+    >while (true)
+    >:=> (line 7, col 0) to (line 7, col 12)
+--------------------------------
+8  >    continue;
+
+    ~~~~~~~~~~~~~~                                => Pos: (76 to 89)  SpanInfo: {"start":80,"length":8}
+    >continue
+    >:=> (line 8, col 4) to (line 8, col 12)
+--------------------------------
+9  >}
+
+    ~~                                            => Pos: (90 to 91)  SpanInfo: {"start":80,"length":8}
+    >continue
+    >:=> (line 8, col 4) to (line 8, col 12)
+--------------------------------
+10 >z: while (true) {
+
+    ~~~~~~~~~~~~~~~~~~                            => Pos: (92 to 109)  SpanInfo: {"start":95,"length":12}
+    >while (true)
+    >:=> (line 10, col 3) to (line 10, col 15)
+--------------------------------
+11 >    continue z;
+
+    ~~~~~~~~~~~~~~~~                              => Pos: (110 to 125)  SpanInfo: {"start":114,"length":10}
+    >continue z
+    >:=> (line 11, col 4) to (line 11, col 14)
+--------------------------------
+12 >}
+    ~                                             => Pos: (126 to 126)  SpanInfo: {"start":114,"length":10}
+    >continue z
+    >:=> (line 11, col 4) to (line 11, col 14)
\ No newline at end of file
diff --git a/tests/baselines/reference/getEmitOutput.baseline b/tests/baselines/reference/getEmitOutput.baseline
new file mode 100644
index 00000000000..fbc3296c7c4
--- /dev/null
+++ b/tests/baselines/reference/getEmitOutput.baseline
@@ -0,0 +1,30 @@
+EmitSkipped: false
+FileName : tests/cases/fourslash/shims/inputFile1.js
+var x = 5;
+var Bar = (function () {
+    function Bar() {
+    }
+    return Bar;
+})();
+FileName : tests/cases/fourslash/shims/inputFile1.d.ts
+declare var x: number;
+declare class Bar {
+    x: string;
+    y: number;
+}
+
+EmitSkipped: false
+FileName : tests/cases/fourslash/shims/inputFile2.js
+var x1 = "hello world";
+var Foo = (function () {
+    function Foo() {
+    }
+    return Foo;
+})();
+FileName : tests/cases/fourslash/shims/inputFile2.d.ts
+declare var x1: string;
+declare class Foo {
+    x: string;
+    y: number;
+}
+
diff --git a/tests/baselines/reference/letInLetOrConstDeclarations.errors.txt b/tests/baselines/reference/letInLetOrConstDeclarations.errors.txt
new file mode 100644
index 00000000000..93dc307fc85
--- /dev/null
+++ b/tests/baselines/reference/letInLetOrConstDeclarations.errors.txt
@@ -0,0 +1,23 @@
+tests/cases/compiler/letInLetOrConstDeclarations.ts(2,9): error TS4089: 'let' is not allowed to be used as a name in 'let' or 'const' declarations.
+tests/cases/compiler/letInLetOrConstDeclarations.ts(3,14): error TS4089: 'let' is not allowed to be used as a name in 'let' or 'const' declarations.
+tests/cases/compiler/letInLetOrConstDeclarations.ts(6,11): error TS4089: 'let' is not allowed to be used as a name in 'let' or 'const' declarations.
+
+
+==== tests/cases/compiler/letInLetOrConstDeclarations.ts (3 errors) ====
+    {
+        let let = 1; // should error
+            ~~~
+!!! error TS4089: 'let' is not allowed to be used as a name in 'let' or 'const' declarations.
+        for (let let in []) { } // should error
+                 ~~~
+!!! error TS4089: 'let' is not allowed to be used as a name in 'let' or 'const' declarations.
+    }
+    {
+        const let = 1; // should error
+              ~~~
+!!! error TS4089: 'let' is not allowed to be used as a name in 'let' or 'const' declarations.
+    }
+    {
+        function let() { // should be ok
+        }
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/letInLetOrConstDeclarations.js b/tests/baselines/reference/letInLetOrConstDeclarations.js
new file mode 100644
index 00000000000..ee23abc4e4f
--- /dev/null
+++ b/tests/baselines/reference/letInLetOrConstDeclarations.js
@@ -0,0 +1,25 @@
+//// [letInLetOrConstDeclarations.ts]
+{
+    let let = 1; // should error
+    for (let let in []) { } // should error
+}
+{
+    const let = 1; // should error
+}
+{
+    function let() { // should be ok
+    }
+}
+
+//// [letInLetOrConstDeclarations.js]
+{
+    let let = 1; // should error
+    for (let let in []) { } // should error
+}
+{
+    const let = 1; // should error
+}
+{
+    function let() {
+    }
+}
diff --git a/tests/cases/compiler/letInLetOrConstDeclarations.ts b/tests/cases/compiler/letInLetOrConstDeclarations.ts
new file mode 100644
index 00000000000..c622759a459
--- /dev/null
+++ b/tests/cases/compiler/letInLetOrConstDeclarations.ts
@@ -0,0 +1,12 @@
+// @target: es6
+{
+    let let = 1; // should error
+    for (let let in []) { } // should error
+}
+{
+    const let = 1; // should error
+}
+{
+    function let() { // should be ok
+    }
+}
\ No newline at end of file
diff --git a/tests/cases/conformance/expressions/functionCalls/callWithSpread.ts b/tests/cases/conformance/expressions/functionCalls/callWithSpread.ts
new file mode 100644
index 00000000000..9acba00697a
--- /dev/null
+++ b/tests/cases/conformance/expressions/functionCalls/callWithSpread.ts
@@ -0,0 +1,52 @@
+interface X {
+    foo(x: number, y: number, ...z: string[]);
+}
+
+function foo(x: number, y: number, ...z: string[]) {
+}
+
+var a: string[];
+var z: number[];
+var obj: X;
+var xa: X[];
+
+foo(1, 2, "abc");
+foo(1, 2, ...a);
+foo(1, 2, ...a, "abc");
+
+obj.foo(1, 2, "abc");
+obj.foo(1, 2, ...a);
+obj.foo(1, 2, ...a, "abc");
+
+(obj.foo)(1, 2, "abc");
+(obj.foo)(1, 2, ...a);
+(obj.foo)(1, 2, ...a, "abc");
+
+xa[1].foo(1, 2, "abc");
+xa[1].foo(1, 2, ...a);
+xa[1].foo(1, 2, ...a, "abc");
+
+(<Function>xa[1].foo)(...[1, 2, "abc"]);
+
+class C {
+    constructor(x: number, y: number, ...z: string[]) {
+        this.foo(x, y);
+        this.foo(x, y, ...z);
+    }
+    foo(x: number, y: number, ...z: string[]) {
+    }
+}
+
+class D extends C {
+    constructor() {
+        super(1, 2);
+        super(1, 2, ...a);
+    }
+    foo() {
+        super.foo(1, 2);
+        super.foo(1, 2, ...a);
+    }
+}
+
+// Only supported in when target is ES6
+var c = new C(1, 2, ...a);
diff --git a/tests/cases/conformance/expressions/functionCalls/callWithSpreadES6.ts b/tests/cases/conformance/expressions/functionCalls/callWithSpreadES6.ts
new file mode 100644
index 00000000000..2f7d16ba368
--- /dev/null
+++ b/tests/cases/conformance/expressions/functionCalls/callWithSpreadES6.ts
@@ -0,0 +1,54 @@
+// @target: ES6
+
+interface X {
+    foo(x: number, y: number, ...z: string[]);
+}
+
+function foo(x: number, y: number, ...z: string[]) {
+}
+
+var a: string[];
+var z: number[];
+var obj: X;
+var xa: X[];
+
+foo(1, 2, "abc");
+foo(1, 2, ...a);
+foo(1, 2, ...a, "abc");
+
+obj.foo(1, 2, "abc");
+obj.foo(1, 2, ...a);
+obj.foo(1, 2, ...a, "abc");
+
+(obj.foo)(1, 2, "abc");
+(obj.foo)(1, 2, ...a);
+(obj.foo)(1, 2, ...a, "abc");
+
+xa[1].foo(1, 2, "abc");
+xa[1].foo(1, 2, ...a);
+xa[1].foo(1, 2, ...a, "abc");
+
+(<Function>xa[1].foo)(...[1, 2, "abc"]);
+
+class C {
+    constructor(x: number, y: number, ...z: string[]) {
+        this.foo(x, y);
+        this.foo(x, y, ...z);
+    }
+    foo(x: number, y: number, ...z: string[]) {
+    }
+}
+
+class D extends C {
+    constructor() {
+        super(1, 2);
+        super(1, 2, ...a);
+    }
+    foo() {
+        super.foo(1, 2);
+        super.foo(1, 2, ...a);
+    }
+}
+
+// Only supported in when target is ES6
+var c = new C(1, 2, ...a);
diff --git a/tests/cases/fourslash/addMethodToInterface1.ts b/tests/cases/fourslash/addMethodToInterface1.ts
index 749f5601173..07cd4700583 100644
--- a/tests/cases/fourslash/addMethodToInterface1.ts
+++ b/tests/cases/fourslash/addMethodToInterface1.ts
@@ -12,4 +12,3 @@ edit.disableFormatting();
 goTo.marker('1');
 
 edit.insert("    compareTo(): number;\n");
-diagnostics.validateTypesAtPositions(168,84,53,118,22);
diff --git a/tests/cases/fourslash/arrayConcatTypeCheck0.ts b/tests/cases/fourslash/arrayConcatTypeCheck0.ts
index ac5404266a6..9250eb5b6fd 100644
--- a/tests/cases/fourslash/arrayConcatTypeCheck0.ts
+++ b/tests/cases/fourslash/arrayConcatTypeCheck0.ts
@@ -14,4 +14,3 @@ edit.disableFormatting();
 goTo.marker('1');
 
 edit.insert(", 'world'");
-diagnostics.validateTypesAtPositions(78);
diff --git a/tests/cases/fourslash/arrayConcatTypeCheck1.ts b/tests/cases/fourslash/arrayConcatTypeCheck1.ts
index 42d9cdb8a1c..c62bd5b7f14 100644
--- a/tests/cases/fourslash/arrayConcatTypeCheck1.ts
+++ b/tests/cases/fourslash/arrayConcatTypeCheck1.ts
@@ -23,5 +23,4 @@ goTo.marker('2');
 edit.deleteAtCaret(7);
 
 goTo.marker('4');
-diagnostics.validateTypesAtPositions(43);
 
diff --git a/tests/cases/fourslash/arrayTypeMismatchIncrementalTypeCheck.ts b/tests/cases/fourslash/arrayTypeMismatchIncrementalTypeCheck.ts
deleted file mode 100644
index 778f20db219..00000000000
--- a/tests/cases/fourslash/arrayTypeMismatchIncrementalTypeCheck.ts
+++ /dev/null
@@ -1,31 +0,0 @@
-/// <reference path="../fourslash.ts" />
-
-//// interface Iterator<T> {
-////     (value: T, index: any): U;
-//// }
-//// 
-//// interface WrappedArray<T> {
-////     map<U>(iterator: Iterator<T, U>): U[];
-//// }
-//// 
-//// interface Underscore {
-////     <T>(list: T[]): WrappedArray<T>;
-////     map<T, U>(list: T[], iterator: Iterator<T, U>, context?: any): U[];
-//// }
-//// 
-//// declare var _: Underscore;
-//// 
-//// var a: string[];
-//// var b = _.map(a, x => x.length);    // Type any[], should be number[]
-//// var c = _(a).map();
-//// var d = a.map(x => x.length);
-//// var bb = _.map(aa, x => x.length);
-//// var cc = _(aa).map(x => x.length);  // Error, could not select overload
-//// var dd = aa.map(x => x.length);     // Error, could not select overload
-//// 
-//// 
-//// 
-//// 
-
-edit.disableFormatting();
-diagnostics.validateTypesAtPositions(364);
diff --git a/tests/cases/fourslash/emptyTypeArgumentList.ts b/tests/cases/fourslash/emptyTypeArgumentList.ts
deleted file mode 100644
index d8f7947559b..00000000000
--- a/tests/cases/fourslash/emptyTypeArgumentList.ts
+++ /dev/null
@@ -1,7 +0,0 @@
-/// <reference path="fourslash.ts" />
-
-//// function foo2<T>(test);
-//// function foo2<T>() { }
-//// /**/foo2<>("");
-goTo.marker();
-diagnostics.validateTypeAtCurrentPosition();
diff --git a/tests/cases/fourslash/fourslash.ts b/tests/cases/fourslash/fourslash.ts
index 267f2c14341..4091815ce59 100644
--- a/tests/cases/fourslash/fourslash.ts
+++ b/tests/cases/fourslash/fourslash.ts
@@ -80,16 +80,6 @@ module FourSlashInterface {
         }
     }
 
-    export class diagnostics {
-        public validateTypeAtCurrentPosition() {
-            return this.validateTypesAtPositions(FourSlash.currentTestState.currentCaretPosition);
-        }
-
-        public validateTypesAtPositions(...positions: number[]) {
-            return FourSlash.currentTestState.verifyTypesAgainstFullCheckAtPositions(positions);
-        }
-    }
-
     export class goTo {
         // Moves the caret to the specified marker,
         // or the anonymous marker ('/**/') if no name
@@ -565,11 +555,11 @@ module FourSlashInterface {
 
     export class cancellation {
         public resetCancelled() {
-            FourSlash.currentTestState.cancellationToken.resetCancelled();
+            FourSlash.currentTestState.resetCancelled();
         }
 
         public setCancelled(numberOfCalls: number = 0) {
-            FourSlash.currentTestState.cancellationToken.setCancelled(numberOfCalls);
+            FourSlash.currentTestState.setCancelled(numberOfCalls);
         }
     }
 
@@ -651,7 +641,6 @@ module fs {
     export var edit = new FourSlashInterface.edit();
     export var debug = new FourSlashInterface.debug();
     export var format = new FourSlashInterface.format();
-    export var diagnostics = new FourSlashInterface.diagnostics();
     export var cancellation = new FourSlashInterface.cancellation();
 }
 module ts {
@@ -670,6 +659,5 @@ var verify = new FourSlashInterface.verify();
 var edit = new FourSlashInterface.edit();
 var debug = new FourSlashInterface.debug();
 var format = new FourSlashInterface.format();
-var diagnostics = new FourSlashInterface.diagnostics();
 var cancellation = new FourSlashInterface.cancellation();
 var classification = FourSlashInterface.classification;
diff --git a/tests/cases/fourslash/getTypeAtModuleExtends.ts b/tests/cases/fourslash/getTypeAtModuleExtends.ts
deleted file mode 100644
index 8114ee94c1b..00000000000
--- a/tests/cases/fourslash/getTypeAtModuleExtends.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-/// <reference path="fourslash.ts" />
-
-////declare module A.B {
-////    export class C { }
-////}
-////
-////import ab = A.B;
-////
-////class D extends ab.C/**/{ }
-
-goTo.marker();
-diagnostics.validateTypesAtPositions(FourSlash.currentTestState.currentCaretPosition);
diff --git a/tests/cases/fourslash/indentation.ts b/tests/cases/fourslash/indentation.ts
index 32319ae282d..2a2090c1d87 100644
--- a/tests/cases/fourslash/indentation.ts
+++ b/tests/cases/fourslash/indentation.ts
@@ -179,5 +179,5 @@
 ////{| "indent": 0 |} 
 
 test.markers().forEach((marker) => {
-        verify.indentationAtPositionIs('tests/cases/fourslash/indentation.ts', marker.position, marker.data.indent);
+        verify.indentationAtPositionIs(marker.fileName, marker.position, marker.data.indent);
     });
diff --git a/tests/cases/fourslash/numberAssignement0.ts b/tests/cases/fourslash/numberAssignement0.ts
deleted file mode 100644
index 540a8d91f3d..00000000000
--- a/tests/cases/fourslash/numberAssignement0.ts
+++ /dev/null
@@ -1,8 +0,0 @@
-/// <reference path="fourslash.ts" />
-
-//// var x: Number;
-//// var y: Number;
-//// var z = x ;
-
-edit.disableFormatting();
-diagnostics.validateTypesAtPositions(28);
diff --git a/tests/cases/fourslash/pullFullDiffTypeParameterExtends0.ts b/tests/cases/fourslash/pullFullDiffTypeParameterExtends0.ts
deleted file mode 100644
index 990d65404d3..00000000000
--- a/tests/cases/fourslash/pullFullDiffTypeParameterExtends0.ts
+++ /dev/null
@@ -1,29 +0,0 @@
-/// <reference path="fourslash.ts" />
-
-//// class A<T, U extends T> { }
-//// class B<T extends Object, U extends T> {
-////     data: A<Object, Object>;
-//// }
-//// 
-//// // Below 2 should compile without error 
-//// var x: A< { }, { b: number }>;
-//// var y: B< { a: string }, { }>;
-//// 
-//// 
-//// // Below should be in error
-//// var x1: A<{ a: string;}>;
-//// var x2: A<{ a: number }>;
-//// var x3: B<{ a: string;}, { b: string }>;
-//// var x4: B<{ a: string;}>;
-//// var x5: A<{ a: string; b: number }, { a: string }>;
-//// var x6: B<>;
-//// 
-//// interface I1 {
-////     a: string;
-//// }
-//// var x8: B<I2, I1>;
-//// 
-
-edit.disableFormatting();
-diagnostics.validateTypesAtPositions(34);
-
diff --git a/tests/cases/fourslash/restParametersTypeValidation1.ts b/tests/cases/fourslash/restParametersTypeValidation1.ts
deleted file mode 100644
index b598ae7fc84..00000000000
--- a/tests/cases/fourslash/restParametersTypeValidation1.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-/// <reference path="fourslash.ts" />
-
-//// function f18(a?:string, ...b){}
-////  
-//// function f19(a?:string, b?){}
-////  
-//// function f20(a:string, b?:string, ...c:number[]){}
-////  
-//// function f21(a:string, b?:string, ...d:number[]){}
-
-edit.disableFormatting();
-diagnostics.validateTypesAtPositions(133);
diff --git a/tests/cases/fourslash/shims/cancellationWhenfindingAllRefsOnDefinition.ts b/tests/cases/fourslash/shims/cancellationWhenfindingAllRefsOnDefinition.ts
new file mode 100644
index 00000000000..09f580bb965
--- /dev/null
+++ b/tests/cases/fourslash/shims/cancellationWhenfindingAllRefsOnDefinition.ts
@@ -0,0 +1,38 @@
+/// <reference path="fourslash.ts" />
+
+//@Filename: findAllRefsOnDefinition-import.ts
+////export class Test{
+////
+////    constructor(){
+////
+////    }
+////
+////    public /*1*/start(){
+////        return this;
+////    }
+////
+////    public stop(){
+////        return this;
+////    }
+////}
+
+//@Filename: findAllRefsOnDefinition.ts
+////import Second = require("findAllRefsOnDefinition-import");
+////
+////var second = new Second.Test()
+////second.start();
+////second.stop();
+
+goTo.file("findAllRefsOnDefinition-import.ts");
+goTo.marker("1");
+
+verify.referencesCountIs(2);
+
+cancellation.setCancelled();
+goTo.marker("1");
+verifyOperationIsCancelled(() => verify.referencesCountIs(0) );
+
+// verify that internal state is still correct
+cancellation.resetCancelled();
+goTo.marker("1");           
+verify.referencesCountIs(2);
diff --git a/tests/cases/fourslash/shims/getBraceMatchingAtPosition.ts b/tests/cases/fourslash/shims/getBraceMatchingAtPosition.ts
new file mode 100644
index 00000000000..fc8a71197db
--- /dev/null
+++ b/tests/cases/fourslash/shims/getBraceMatchingAtPosition.ts
@@ -0,0 +1,43 @@
+/// <reference path="fourslash.ts"/>
+
+//////curly braces
+////module Foo [|{
+////    class Bar [|{
+////        private f() [|{
+////        }|]
+////
+////        private f2() [|{
+////            if (true) [|{ }|] [|{ }|];
+////        }|]
+////    }|]
+////}|]
+////
+//////parenthesis
+////class FooBar {
+////    private f[|()|] {
+////        return [|([|(1 + 1)|])|];
+////    }
+////
+////    private f2[|()|] {
+////        if [|(true)|] { }
+////    }
+////}
+////
+//////square brackets
+////class Baz {
+////    private f() {
+////        var a: any[|[]|] = [|[[|[1, 2]|], [|[3, 4]|], 5]|];
+////    }
+////}
+////
+////// angular brackets
+////class TemplateTest [|<T1, T2 extends Array>|] {
+////    public foo(a, b) {
+////        return [|<any>|] a;
+////    }
+////}
+
+test.ranges().forEach((range) => {
+    verify.matchingBracePositionInCurrentFile(range.start, range.end - 1);
+    verify.matchingBracePositionInCurrentFile(range.end - 1, range.start);
+});
\ No newline at end of file
diff --git a/tests/cases/fourslash/shims/getBreakpointStatementAtPosition.ts b/tests/cases/fourslash/shims/getBreakpointStatementAtPosition.ts
new file mode 100644
index 00000000000..9e1d075a17f
--- /dev/null
+++ b/tests/cases/fourslash/shims/getBreakpointStatementAtPosition.ts
@@ -0,0 +1,17 @@
+/// <reference path='fourslash.ts' />
+
+// @BaselineFile: getBreakpointStatementAtPosition.baseline
+// @Filename: getBreakpointStatementAtPosition.ts
+////while (true) {
+////    break;
+////}
+////y: while (true) {
+////    break y;
+////}
+////while (true) {
+////    continue;
+////}
+////z: while (true) {
+////    continue z;
+////}
+verify.baselineCurrentFileBreakpointLocations();
\ No newline at end of file
diff --git a/tests/cases/fourslash/shims/getCompletionsAtPosition.ts b/tests/cases/fourslash/shims/getCompletionsAtPosition.ts
new file mode 100644
index 00000000000..714d3390e76
--- /dev/null
+++ b/tests/cases/fourslash/shims/getCompletionsAtPosition.ts
@@ -0,0 +1,20 @@
+/// <reference path='fourslash.ts'/>
+
+////function foo(strOrNum: string | number) {
+////    /*1*/
+////    if (typeof strOrNum === "number") {
+////        /*2*/ 
+////    }
+////    else {
+////        /*3*/
+////    }
+////}
+
+goTo.marker('1');
+verify.completionListContains("strOrNum", "(parameter) strOrNum: string | number");
+
+goTo.marker('2');
+verify.completionListContains("strOrNum", "(parameter) strOrNum: number");
+
+goTo.marker('3');
+verify.completionListContains("strOrNum", "(parameter) strOrNum: string");
\ No newline at end of file
diff --git a/tests/cases/fourslash/shims/getDefinitionAtPosition.ts b/tests/cases/fourslash/shims/getDefinitionAtPosition.ts
new file mode 100644
index 00000000000..54b799ba65f
--- /dev/null
+++ b/tests/cases/fourslash/shims/getDefinitionAtPosition.ts
@@ -0,0 +1,29 @@
+/// <reference path='fourslash.ts' />
+
+// @Filename: goToDefinitionDifferentFile_Definition.ts
+////var /*remoteVariableDefinition*/remoteVariable;
+/////*remoteFunctionDefinition*/function remoteFunction() { }
+/////*remoteClassDefinition*/class remoteClass { }
+/////*remoteInterfaceDefinition*/interface remoteInterface{ }
+/////*remoteModuleDefinition*/module remoteModule{ export var foo = 1;}
+
+// @Filename: goToDefinitionDifferentFile_Consumption.ts
+/////*remoteVariableReference*/remoteVariable = 1;
+/////*remoteFunctionReference*/remoteFunction();
+////var foo = new /*remoteClassReference*/remoteClass();
+////class fooCls implements /*remoteInterfaceReference*/remoteInterface { }
+////var fooVar = /*remoteModuleReference*/remoteModule.foo;
+
+var markerList = [
+    "remoteVariable",
+    "remoteFunction",
+    "remoteClass",
+    "remoteInterface",
+    "remoteModule",
+];
+
+markerList.forEach((marker) => {
+    goTo.marker(marker + 'Reference');
+    goTo.definition();
+    verify.caretAtMarker(marker + 'Definition');
+});
diff --git a/tests/cases/fourslash/shims/getEmitOutput.ts b/tests/cases/fourslash/shims/getEmitOutput.ts
new file mode 100644
index 00000000000..699514521ed
--- /dev/null
+++ b/tests/cases/fourslash/shims/getEmitOutput.ts
@@ -0,0 +1,22 @@
+/// <reference path="fourslash.ts" />
+
+// @BaselineFile: getEmitOutput.baseline
+// @declaration: true
+
+// @Filename: inputFile1.ts
+// @emitThisFile: true
+//// var x: number = 5;
+//// class Bar {
+////    x : string;
+////    y : number
+//// }
+
+// @Filename: inputFile2.ts
+// @emitThisFile: true
+//// var x1: string = "hello world";
+//// class Foo{
+////    x : string;
+////    y : number;
+//// }
+
+verify.baselineGetEmitOutput();
\ No newline at end of file
diff --git a/tests/cases/fourslash/shims/getIndentationAtPosition.ts b/tests/cases/fourslash/shims/getIndentationAtPosition.ts
new file mode 100644
index 00000000000..5e26781357e
--- /dev/null
+++ b/tests/cases/fourslash/shims/getIndentationAtPosition.ts
@@ -0,0 +1,21 @@
+/// <reference path='fourslash.ts'/>
+
+////class Bar {
+////    {| "indentation": 4|}
+////    private foo: string = "";
+////    {| "indentation": 4|}
+////    private f() {
+////        var a: any[] = [[1, 2], [3, 4], 5];
+////        {| "indentation": 8|}
+////        return ((1 + 1));
+////    }
+////    {| "indentation": 4|}
+////    private f2() {
+////        if (true) { } { };
+////    }
+////}
+////{| "indentation": 0|}
+
+test.markers().forEach((marker) => {
+    verify.indentationAtPositionIs(marker.fileName, marker.position, marker.data.indentation);
+});
diff --git a/tests/cases/fourslash/shims/getNavigateToItems.ts b/tests/cases/fourslash/shims/getNavigateToItems.ts
new file mode 100644
index 00000000000..9658c52324c
--- /dev/null
+++ b/tests/cases/fourslash/shims/getNavigateToItems.ts
@@ -0,0 +1,27 @@
+/// <reference path="fourslash.ts"/>
+
+/////// Module
+////{| "itemName": "Shapes", "kind": "module", "parentName": "" |}module Shapes {
+////
+////    // Class
+////    {| "itemName": "Point", "kind": "class", "parentName": "Shapes" |}export class Point {
+////        // Instance member
+////        {| "itemName": "origin", "kind": "property", "parentName": "Point", "matchKind": "exact"|}private origin = 0.0;
+////        
+////        {| "itemName": "distFromZero", "kind": "property", "parentName": "Point", "matchKind": "exact"|}private distFromZero = 0.0;
+////
+////        // Getter
+////        {| "itemName": "distance", "kind": "getter", "parentName": "Point", "matchKind": "exact" |}get distance(): number { return 0; }
+////    }
+////}
+////
+////// Local variables
+////{| "itemName": "point", "kind": "var", "parentName": "", "matchKind": "exact"|}var point = new Shapes.Point();
+
+//// Testing for exact matching of navigationItems
+
+test.markers().forEach((marker) => {
+    if (marker.data) {
+        verify.navigationItemsListContains(marker.data.itemName, marker.data.kind, marker.data.itemName, marker.data.matchKind, marker.fileName, marker.data.parentName);
+    }
+});
diff --git a/tests/cases/fourslash/shims/getNavigationBarItems.ts b/tests/cases/fourslash/shims/getNavigationBarItems.ts
new file mode 100644
index 00000000000..6c0738747f3
--- /dev/null
+++ b/tests/cases/fourslash/shims/getNavigationBarItems.ts
@@ -0,0 +1,13 @@
+/// <reference path="fourslash.ts" />
+
+//// {| "itemName": "c", "kind": "const", "parentName": "" |}const c = 0;
+
+test.markers().forEach(marker => {
+    verify.getScriptLexicalStructureListContains(
+        marker.data.itemName,
+        marker.data.kind,
+        marker.fileName,
+        marker.data.parentName,
+        marker.data.isAdditionalRange,
+        marker.position);
+});
\ No newline at end of file
diff --git a/tests/cases/fourslash/shims/getOccurrencesAtPosition.ts b/tests/cases/fourslash/shims/getOccurrencesAtPosition.ts
new file mode 100644
index 00000000000..0654cc3962c
--- /dev/null
+++ b/tests/cases/fourslash/shims/getOccurrencesAtPosition.ts
@@ -0,0 +1,18 @@
+/// <reference path='fourslash.ts'/>
+
+/////*0*/
+////interface A {
+////    foo: string;
+////}
+////function foo(x: A) {
+////    x.f/*1*/oo
+////}
+
+goTo.marker("1");
+verify.occurrencesAtPositionCount(2);
+
+goTo.marker("0");
+edit.insert("\r\n");
+
+goTo.marker("1");
+verify.occurrencesAtPositionCount(2);
\ No newline at end of file
diff --git a/tests/cases/fourslash/shims/getOutliningSpans.ts b/tests/cases/fourslash/shims/getOutliningSpans.ts
new file mode 100644
index 00000000000..93665889eb4
--- /dev/null
+++ b/tests/cases/fourslash/shims/getOutliningSpans.ts
@@ -0,0 +1,113 @@
+/// <reference path="fourslash.ts"/>
+
+////// interface 
+////interface IFoo[| {
+////    getDist(): number;
+////}|]
+////
+////// class members
+////class Foo[| {
+////    constructor()[| {
+////    }|]
+////
+////    public foo(): number[| {
+////        return 0;
+////    }|]
+////
+////    public get X()[| {
+////        return 1;
+////    }|]
+////
+////    public set X(v: number)[| {
+////    }|]
+////
+////    public member = function f()[| {
+////
+////    }|]
+////}|]
+////switch(1)[| {
+//// case 1: break;
+////}|]
+////
+////var array =[| [
+////    1,
+////    2
+////]|]
+////
+////// modules
+////module m1[| {
+////    module m2[| { }|]
+////    module m3[| {
+////        function foo()[| {
+////
+////        }|]
+////
+////        interface IFoo2[| {
+////
+////        }|]
+////
+////        class foo2 implements IFoo2[| {
+////
+////        }|]
+////    }|]
+////}|]
+////
+////// function declaration
+////function foo(): number[| {
+////    return 0;
+////}|]
+////
+////// function expressions
+////(function f()[| {
+////
+////}|])
+////
+////// trivia handeling
+////class ClassFooWithTrivia[| /*  some comments */ 
+////   /* more trivia */ {
+////    
+////
+////    /*some trailing trivia */
+////}|] /* even more */
+////
+////// object literals
+////var x =[|{
+////  a:1,
+////  b:2,
+////  get foo()[| {
+////    return 1;
+////  }|]
+////}|]
+//////outline with deep nesting
+////module m1[|{
+////    module m2[| {
+////        module m3[| {
+////            module m4[| {
+////                module m5[| {
+////                    module m6[| {
+////                        module m7[| {
+////                            module m8[| {
+////                                module m9[| {
+////                                    module m10[| {
+////                                        module m11 {
+////                                            module m12 {
+////                                                export interface IFoo {
+////                                                }
+////                                            }
+////                                        }
+////                                    }|]
+////                                }|]
+////                            }|]
+////                        }|]
+////                    }|]
+////                }|]
+////            }|]
+////        }|]
+////    }|]
+////}|]
+////
+//////outline after a deeply nested node
+////class AfterNestedNodes[| {
+////}|]
+
+verify.outliningSpansInCurrentFile(test.ranges());
diff --git a/tests/cases/fourslash/shims/getPreProcessedFile.ts b/tests/cases/fourslash/shims/getPreProcessedFile.ts
new file mode 100644
index 00000000000..abd26bb6e4b
--- /dev/null
+++ b/tests/cases/fourslash/shims/getPreProcessedFile.ts
@@ -0,0 +1,32 @@
+/// <reference path="fourslash.ts" />
+
+// @Filename: refFile1.ts
+//// class D { }
+
+// @Filename: refFile2.ts
+//// export class E {} 
+
+// @Filename: main.ts
+// @ResolveReference: true
+//// ///<reference path="refFile1.ts" />
+//// /*1*////<reference path = "NotExistRef.ts" />/*2*/
+//// /*3*////<reference path "invalidRefFile1.ts" />/*4*/
+//// import ref2 = require("refFile2");
+//// import noExistref2 = require(/*5*/"NotExistRefFile2"/*6*/);
+//// import invalidRef1  /*7*/require/*8*/("refFile2");
+//// /*9*/import invalidRef2 = requi/*10*/("refFile2");
+//// var obj: /*11*/C/*12*/;
+//// var obj1: D;
+//// var obj2: ref2.E;
+
+goTo.file("main.ts");
+verify.numberOfErrorsInCurrentFile(7);
+verify.errorExistsBetweenMarkers("1", "2");
+verify.errorExistsBetweenMarkers("3", "4");
+verify.errorExistsBetweenMarkers("5", "6");
+verify.errorExistsBetweenMarkers("7", "8");
+verify.errorExistsBetweenMarkers("9", "10");  // At this position,  there are two diagnostic messages: ';' expected, Cannot find name 'requi' 
+verify.errorExistsBetweenMarkers("11", "12");
+
+
+
diff --git a/tests/cases/fourslash/shims/getQuickInfoAtPosition.ts b/tests/cases/fourslash/shims/getQuickInfoAtPosition.ts
new file mode 100644
index 00000000000..6c9fc7cf795
--- /dev/null
+++ b/tests/cases/fourslash/shims/getQuickInfoAtPosition.ts
@@ -0,0 +1,16 @@
+/// <reference path='fourslash.ts'/>
+
+////class SS<T>{}
+////
+////var x/*1*/1 = new SS<number>();
+////var x/*2*/2 = new SS();
+////var x/*3*/3 = new SS;
+
+goTo.marker('1');
+verify.quickInfoIs('(var) x1: SS<number>');
+
+goTo.marker('2');
+verify.quickInfoIs('(var) x2: SS<{}>');
+
+goTo.marker('3');
+verify.quickInfoIs('(var) x3: SS<{}>');
\ No newline at end of file
diff --git a/tests/cases/fourslash/shims/getReferencesAtPosition.ts b/tests/cases/fourslash/shims/getReferencesAtPosition.ts
new file mode 100644
index 00000000000..34144b74899
--- /dev/null
+++ b/tests/cases/fourslash/shims/getReferencesAtPosition.ts
@@ -0,0 +1,29 @@
+/// <reference path="fourslash.ts" />
+
+//@Filename: findAllRefsOnDefinition-import.ts
+////export class Test{
+////
+////    constructor(){
+////
+////    }
+////
+////    public /*1*/start(){
+////        return this;
+////    }
+////
+////    public stop(){
+////        return this;
+////    }
+////}
+
+//@Filename: findAllRefsOnDefinition.ts
+////import Second = require("findAllRefsOnDefinition-import");
+////
+////var second = new Second.Test()
+////second.start();
+////second.stop();
+
+goTo.file("findAllRefsOnDefinition-import.ts");
+goTo.marker("1");
+
+verify.referencesCountIs(2);
\ No newline at end of file
diff --git a/tests/cases/fourslash/shims/getRenameInfo.ts b/tests/cases/fourslash/shims/getRenameInfo.ts
new file mode 100644
index 00000000000..b5c8ac6aacc
--- /dev/null
+++ b/tests/cases/fourslash/shims/getRenameInfo.ts
@@ -0,0 +1,11 @@
+/// <reference path="fourslash.ts" />
+
+///////<reference path="./Bar.ts" /> 
+
+////function /**/[|Bar|]() {
+////    // This is a reference to Bar in a comment.
+////    "this is a reference to Bar in a string"
+////}
+
+goTo.marker();
+verify.renameLocations(/*findInStrings:*/ false, /*findInComments:*/ false);
\ No newline at end of file
diff --git a/tests/cases/fourslash/shims/getSemanticClassifications.ts b/tests/cases/fourslash/shims/getSemanticClassifications.ts
new file mode 100644
index 00000000000..4eb7f2a32ed
--- /dev/null
+++ b/tests/cases/fourslash/shims/getSemanticClassifications.ts
@@ -0,0 +1,15 @@
+/// <reference path="fourslash.ts"/>
+
+//// module /*0*/M {
+////     export interface /*1*/I {
+////     }
+//// }
+//// interface /*2*/X extends /*3*/M./*4*/I { }
+
+var c = classification;
+verify.semanticClassificationsAre(
+    c.moduleName("M", test.marker("0").position),
+    c.interfaceName("I", test.marker("1").position),
+    c.interfaceName("X", test.marker("2").position),
+    c.moduleName("M", test.marker("3").position),
+    c.interfaceName("I", test.marker("4").position));
diff --git a/tests/cases/fourslash/shims/getSemanticDiagnostics.ts b/tests/cases/fourslash/shims/getSemanticDiagnostics.ts
new file mode 100644
index 00000000000..6345c464213
--- /dev/null
+++ b/tests/cases/fourslash/shims/getSemanticDiagnostics.ts
@@ -0,0 +1,11 @@
+/// <reference path="fourslash.ts" />
+
+// @module: CommonJS
+// @declaration: true
+//// interface privateInterface {}
+//// export class Bar implements /*1*/privateInterface/*2*/{ }
+
+verify.errorExistsBetweenMarkers("1", "2");
+verify.numberOfErrorsInCurrentFile(1);
+
+
diff --git a/tests/cases/fourslash/shims/getSignatureHelpItems.ts b/tests/cases/fourslash/shims/getSignatureHelpItems.ts
new file mode 100644
index 00000000000..846c2d5244a
--- /dev/null
+++ b/tests/cases/fourslash/shims/getSignatureHelpItems.ts
@@ -0,0 +1,13 @@
+/// <reference path='fourslash.ts' />
+
+// @Filename: signatureHelpInFunctionCallOnFunctionDeclarationInMultipleFiles_file0.ts
+////declare function fn(x: string, y: number);
+
+// @Filename: signatureHelpInFunctionCallOnFunctionDeclarationInMultipleFiles_file1.ts
+////declare function fn(x: string);
+
+// @Filename: signatureHelpInFunctionCallOnFunctionDeclarationInMultipleFiles_file2.ts
+////fn(/*1*/
+
+goTo.marker('1');
+verify.signatureHelpCountIs(2);
\ No newline at end of file
diff --git a/tests/cases/fourslash/shims/getSyntacticClassifications.ts b/tests/cases/fourslash/shims/getSyntacticClassifications.ts
new file mode 100644
index 00000000000..88f655683a3
--- /dev/null
+++ b/tests/cases/fourslash/shims/getSyntacticClassifications.ts
@@ -0,0 +1,35 @@
+/// <reference path="fourslash.ts"/>
+
+//// // comment
+//// module M {
+////     var v = 0 + 1;
+////     var s = "string";
+////
+////     class C<T> {
+////     }
+////
+////     enum E {
+////     }
+////
+////     interface I {
+////     }
+////
+////     module M1.M2 {
+////     }
+//// }
+
+var c = classification;
+verify.syntacticClassificationsAre(
+    c.comment("// comment"),
+    c.keyword("module"), c.moduleName("M"), c.punctuation("{"),
+        c.keyword("var"), c.text("v"), c.operator("="), c.numericLiteral("0"), c.operator("+"), c.numericLiteral("1"), c.punctuation(";"),
+        c.keyword("var"), c.text("s"), c.operator("="), c.stringLiteral('"string"'), c.punctuation(";"),
+        c.keyword("class"), c.className("C"), c.punctuation("<"), c.typeParameterName("T"), c.punctuation(">"), c.punctuation("{"),
+        c.punctuation("}"),
+        c.keyword("enum"), c.enumName("E"), c.punctuation("{"),
+        c.punctuation("}"),
+        c.keyword("interface"), c.interfaceName("I"), c.punctuation("{"),
+        c.punctuation("}"),
+        c.keyword("module"), c.moduleName("M1"), c.punctuation("."), c.moduleName("M2"), c.punctuation("{"),
+        c.punctuation("}"),
+    c.punctuation("}"));
\ No newline at end of file
diff --git a/tests/cases/fourslash/shims/getTodoComments.ts b/tests/cases/fourslash/shims/getTodoComments.ts
new file mode 100644
index 00000000000..b1e0086b93f
--- /dev/null
+++ b/tests/cases/fourslash/shims/getTodoComments.ts
@@ -0,0 +1,3 @@
+//// // [|TODO|]
+
+verify.todoCommentsInCurrentFile(["TODO"]);
\ No newline at end of file
diff --git a/tests/cases/fourslash/shims/quickInfoDisplayPartsVar.ts b/tests/cases/fourslash/shims/quickInfoDisplayPartsVar.ts
new file mode 100644
index 00000000000..56ccceb3ab3
--- /dev/null
+++ b/tests/cases/fourslash/shims/quickInfoDisplayPartsVar.ts
@@ -0,0 +1,76 @@
+/// <reference path='fourslash.ts'/>
+
+////var /*1*/a = 10;
+////function foo() {
+////    var /*2*/b = /*3*/a;
+////}
+////module m {
+////    var /*4*/c = 10;
+////    export var /*5*/d = 10;
+////}
+////var /*6*/f: () => number;
+////var /*7*/g = /*8*/f;
+/////*9*/f();
+////var /*10*/h: { (a: string): number; (a: number): string; };
+////var /*11*/i = /*12*/h;
+/////*13*/h(10);
+/////*14*/h("hello");
+
+var marker = 0;
+function verifyVar(name: string, isLocal: boolean, typeDisplay: ts.SymbolDisplayPart[], optionalNameDisplay?: ts.SymbolDisplayPart[], optionalKindModifiers?: string) {
+    marker++;
+    goTo.marker(marker.toString());
+    var kind = isLocal ? "local var" : "var";
+    verify.verifyQuickInfoDisplayParts(kind, optionalKindModifiers || "", { start: test.markerByName(marker.toString()).position, length: name.length },
+        [{ text: "(", kind: "punctuation" }, { text: kind, kind: "text" }, { text: ")", kind: "punctuation" },
+            { text: " ", kind: "space" }].concat(optionalNameDisplay || [{ text: name, kind: "localName" }]).concat(
+            { text: ":", kind: "punctuation" }, { text: " ", kind: "space" }).concat(typeDisplay),
+        []);
+}
+
+var numberTypeDisplay: ts.SymbolDisplayPart[] = [{ text: "number", kind: "keyword" }];
+
+verifyVar("a", /*isLocal*/false, numberTypeDisplay);
+verifyVar("b", /*isLocal*/true, numberTypeDisplay);
+verifyVar("a", /*isLocal*/false, numberTypeDisplay);
+verifyVar("c", /*isLocal*/false, numberTypeDisplay);
+verifyVar("d", /*isLocal*/false, numberTypeDisplay, [{ text: "m", kind: "moduleName" }, { text: ".", kind: "punctuation" }, { text: "d", kind: "localName" }], "export");
+
+var functionTypeReturningNumber: ts.SymbolDisplayPart[] = [{ text: "(", kind: "punctuation" }, { text: ")", kind: "punctuation" },
+    { text: " ", kind: "space" }, { text: "=>", kind: "punctuation" }, { text: " ", kind: "space" }, { text: "number", kind: "keyword" }];
+verifyVar("f", /*isLocal*/ false, functionTypeReturningNumber);
+verifyVar("g", /*isLocal*/ false, functionTypeReturningNumber);
+verifyVar("f", /*isLocal*/ false, functionTypeReturningNumber);
+verifyVar("f", /*isLocal*/ false, functionTypeReturningNumber);
+
+
+function getFunctionType(parametertype: string, returnType: string, isArrow?: boolean): ts.SymbolDisplayPart[] {
+    var functionTypeDisplay = [{ text: "(", kind: "punctuation" }, { text: "a", kind: "parameterName" }, { text: ":", kind: "punctuation" },
+        { text: " ", kind: "space" }, { text: parametertype, kind: "keyword" }, { text: ")", kind: "punctuation" }];
+
+    if (isArrow) {
+        functionTypeDisplay = functionTypeDisplay.concat({ text: " ", kind: "space" }, { text: "=>", kind: "punctuation" });
+    }
+    else {
+        functionTypeDisplay = functionTypeDisplay.concat({ text: ":", kind: "punctuation" });
+    }
+
+    return functionTypeDisplay.concat({ text: " ", kind: "space" }, { text: returnType, kind: "keyword" });
+}
+
+var typeLiteralWithOverloadCall: ts.SymbolDisplayPart[] = [{ text: "{", kind: "punctuation" }, { text: "\n", kind: "lineBreak" },
+    { text: "    ", kind: "space" }].concat(getFunctionType("string", "number")).concat(
+    { text: ";", kind: "punctuation" }, { text: "\n", kind: "lineBreak" },
+    { text: "    ", kind: "space" }).concat(getFunctionType("number", "string")).concat(
+    { text: ";", kind: "punctuation" }, { text: "\n", kind: "lineBreak" }, { text: "}", kind: "punctuation" });
+
+verifyVar("h", /*isLocal*/ false, typeLiteralWithOverloadCall);
+verifyVar("i", /*isLocal*/ false, typeLiteralWithOverloadCall);
+verifyVar("h", /*isLocal*/ false, typeLiteralWithOverloadCall);
+
+var overloadDisplay: ts.SymbolDisplayPart[] = [{ text: " ", kind: "space" }, { text: "(", kind: "punctuation" },
+    { text: "+", kind: "operator" }, { text: "1", kind: "numericLiteral" },
+    { text: " ", kind: "space" }, { text: "overload", kind: "text" }, { text: ")", kind: "punctuation" }];
+
+verifyVar("h", /*isLocal*/ false, getFunctionType("number", "string", /*isArrow*/true).concat(overloadDisplay));
+verifyVar("h", /*isLocal*/ false, getFunctionType("string", "number", /*isArrow*/true).concat(overloadDisplay));
\ No newline at end of file
diff --git a/tests/cases/fourslash/typeCheckAfterAddingGenericParameter.ts b/tests/cases/fourslash/typeCheckAfterAddingGenericParameter.ts
index e2e978dd7ea..fa312f3c711 100644
--- a/tests/cases/fourslash/typeCheckAfterAddingGenericParameter.ts
+++ b/tests/cases/fourslash/typeCheckAfterAddingGenericParameter.ts
@@ -20,5 +20,3 @@ edit.insert(", X");
 goTo.marker('addTypeParam');
 
 edit.insert(", X");
-
-diagnostics.validateTypesAtPositions(91, 163);
diff --git a/tests/cases/fourslash/typeCheckExpression0.ts b/tests/cases/fourslash/typeCheckExpression0.ts
deleted file mode 100644
index 51c6ae75655..00000000000
--- a/tests/cases/fourslash/typeCheckExpression0.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-/// <reference path="fourslash.ts" />
-
-//// class Point {
-//// 
-////     constructor(public x: number) {
-//// 
-////     }
-////     getDist() { 
-////     }
-////     static origin = new Point(0);
-//// }
-//// 
-//// class Point3D {
-//// 
-////     constructor(x: number, y: number, private z) {
-////         super(x, y);
-////     }
-////     
-////     getDist() {
-////         return Math.sqrt(this.x*this.x + this.z*this.m);
-////     }        
-//// }
-//// 
-//// 
-
-edit.disableFormatting();
-diagnostics.validateTypesAtPositions(258);
diff --git a/tests/cases/fourslash/typeCheckGenericTypeLiteralArgument.ts b/tests/cases/fourslash/typeCheckGenericTypeLiteralArgument.ts
deleted file mode 100644
index 107c7a3b525..00000000000
--- a/tests/cases/fourslash/typeCheckGenericTypeLiteralArgument.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-/// <reference path="fourslash.ts" />
-
-//// interface Sequence<T> {
-////     each(iterator: (value: T) => void): void;
-////     filter(): Sequence<T>;
-////     groupBy<K>(keySelector: () => K): Sequence<{ items: T/**/[]; }>;
-//// }
-
-goTo.file(0);
-
-// Marker in above file is placed at position 154
-diagnostics.validateTypesAtPositions(154);
diff --git a/tests/cases/fourslash/typeCheckIndexSignature.ts b/tests/cases/fourslash/typeCheckIndexSignature.ts
deleted file mode 100644
index a0c7d049b93..00000000000
--- a/tests/cases/fourslash/typeCheckIndexSignature.ts
+++ /dev/null
@@ -1,11 +0,0 @@
-/// <reference path="fourslash.ts" />
-
-//// function method() {
-////     var dictionary = <{ [index: string]: string; }>{};
-//// }
-//// 
-
-edit.disableFormatting(); // Disregard, just here to keep Fourslash happy
-
-diagnostics.validateTypesAtPositions(44);
-
diff --git a/tests/cases/fourslash/typeCheckIndexerAccess1.ts b/tests/cases/fourslash/typeCheckIndexerAccess1.ts
deleted file mode 100644
index 384f6d003e2..00000000000
--- a/tests/cases/fourslash/typeCheckIndexerAccess1.ts
+++ /dev/null
@@ -1,40 +0,0 @@
-/// <reference path="fourslash.ts" />
-
-//// // @sourcemap: true
-//// module Foo.Bar {
-////     "use strict";
-//// 
-////     class Greeter {
-////         constructor(public greeting: string) {
-////         }
-//// 
-////         greet() {
-////         }
-////     }
-//// 
-//// 
-////     function foo(greeting: string): Foo.Bar.Greeter {
-////         return new Greeter(greeting);
-////     }
-//// 
-////     var greeter = new Greeter("Hello, world!");
-////     var str = greeter.greet();
-//// 
-////     function foo2(greeting: string, ...restGreetings) {
-////         var greeters: Greeter[] = [];
-//// new Greeter(greeting);
-////         for (var i = 0; restGreetings.length; i++) {
-////             greeters.push(new Greeter(restGreetings[i]));
-////         }
-//// 
-////         return greeters;
-////     }
-//// 
-////     var b = foo2("Hello", "World");
-////     for (var j = 0; j < b.length; j++) {
-////         b[j].greet();
-////     }
-//// }
-
-edit.disableFormatting();
-diagnostics.validateTypesAtPositions(705);
\ No newline at end of file
diff --git a/tests/cases/unittests/services/colorization.ts b/tests/cases/unittests/services/colorization.ts
index 20038800a3e..01149764305 100644
--- a/tests/cases/unittests/services/colorization.ts
+++ b/tests/cases/unittests/services/colorization.ts
@@ -1,84 +1,47 @@
 /// <reference path="..\..\..\..\src\harness\external\mocha.d.ts" />
 /// <reference path="..\..\..\..\src\harness\harnessLanguageService.ts" />
 
-interface Classification {
-    position: number;
-    length: number;
-    class: ts.TokenClass;
-}
-
-interface ClassiferResult {
-    tuples: Classification[];
-    finalEndOfLineState: ts.EndOfLineState;
-}
-
 interface ClassificationEntry {
     value: any;
-    class: ts.TokenClass;
+    classification: ts.TokenClass;
 }
 
 describe('Colorization', function () {
-    var mytypescriptLS = new Harness.LanguageService.TypeScriptLS();
-    var myclassifier = mytypescriptLS.getClassifier();
+    // Use the shim adapter to ensure test coverage of the shim layer for the classifier
+    var languageServiceAdabtor = new Harness.LanguageService.ShimLanugageServiceAdapter();
+    var classifier = languageServiceAdabtor.getClassifier();
 
-    function getLexicalClassifications(code: string, initialEndOfLineState: ts.EndOfLineState = ts.EndOfLineState.Start): ClassiferResult {
-        var classResult = myclassifier.getClassificationsForLine(code, initialEndOfLineState).split('\n');
-        var tuples: Classification[] = [];
-        var i = 0;
-        var position = 0;
-
-        for (; i < classResult.length - 1; i += 2) {
-            var t = tuples[i / 2] = {
-                position: position,
-                length: parseInt(classResult[i]),
-                class: parseInt(classResult[i + 1])
-            };
-
-            assert.isTrue(t.length > 0, "Result length should be greater than 0, got :" + t.length);
-            position += t.length;
-        }
-        var finalEndOfLineState = classResult[classResult.length - 1];
-
-        assert.equal(position, code.length, "Expected cumulative length of all entries to match the length of the source. expected: " + code.length + ", but got: " + position);
-
-        return {
-            tuples: tuples,
-            finalEndOfLineState: parseInt(finalEndOfLineState)
-        };
-    }
-
-    function verifyClassification(classification: Classification, expectedLength: number, expectedClass: number) {
-        assert.isNotNull(classification);
-        assert.equal(classification.length, expectedLength, "Classification length does not match expected. Expected: " + expectedLength + ", Actual: " + classification.length);
-        assert.equal(classification.class, expectedClass, "Classification class does not match expected. Expected: " + ts.TokenClass[expectedClass] + ", Actual: " + ts.TokenClass[classification.class]);
-    }
-
-    function getEntryAtPosistion(result: ClassiferResult, position: number) {
-        for (var i = 0, n = result.tuples.length; i < n; i++) {
-            if (result.tuples[i].position === position) return result.tuples[i];
+    function getEntryAtPosistion(result: ts.ClassificationResult, position: number) {
+        var entryPosition = 0;
+        for (var i = 0, n = result.entries.length; i < n; i++) {
+            var entry = result.entries[i];
+            if (entryPosition === position) {
+                return entry;
+            }
+            entryPosition += entry.length;
         }
         return undefined;
     }
 
-    function punctuation(text: string) { return { value: text, class: ts.TokenClass.Punctuation }; }
-    function keyword(text: string) { return { value: text, class: ts.TokenClass.Keyword }; }
-    function operator(text: string) { return { value: text, class: ts.TokenClass.Operator }; }
-    function comment(text: string) { return { value: text, class: ts.TokenClass.Comment }; }
-    function whitespace(text: string) { return { value: text, class: ts.TokenClass.Whitespace }; }
-    function identifier(text: string) { return { value: text, class: ts.TokenClass.Identifier }; }
-    function numberLiteral(text: string) { return { value: text, class: ts.TokenClass.NumberLiteral }; }
-    function stringLiteral(text: string) { return { value: text, class: ts.TokenClass.StringLiteral }; }
-    function regExpLiteral(text: string) { return { value: text, class: ts.TokenClass.RegExpLiteral }; }
-    function finalEndOfLineState(value: number) { return { value: value, class: <ts.TokenClass>undefined }; }
+    function punctuation(text: string): ClassificationEntry { return { value: text, classification: ts.TokenClass.Punctuation }; }
+    function keyword(text: string): ClassificationEntry { return { value: text, classification: ts.TokenClass.Keyword }; }
+    function operator(text: string): ClassificationEntry { return { value: text, classification: ts.TokenClass.Operator }; }
+    function comment(text: string): ClassificationEntry { return { value: text, classification: ts.TokenClass.Comment }; }
+    function whitespace(text: string): ClassificationEntry { return { value: text, classification: ts.TokenClass.Whitespace }; }
+    function identifier(text: string): ClassificationEntry { return { value: text, classification: ts.TokenClass.Identifier }; }
+    function numberLiteral(text: string): ClassificationEntry { return { value: text, classification: ts.TokenClass.NumberLiteral }; }
+    function stringLiteral(text: string): ClassificationEntry { return { value: text, classification: ts.TokenClass.StringLiteral }; }
+    function regExpLiteral(text: string): ClassificationEntry { return { value: text, classification: ts.TokenClass.RegExpLiteral }; }
+    function finalEndOfLineState(value: number): ClassificationEntry { return { value: value, classification: <ts.TokenClass>undefined }; }
 
     function testLexicalClassification(text: string, initialEndOfLineState: ts.EndOfLineState, ...expectedEntries: ClassificationEntry[]): void {
-        var result = getLexicalClassifications(text, initialEndOfLineState);
+        var result = classifier.getClassificationsForLine(text, initialEndOfLineState);
 
         for (var i = 0, n = expectedEntries.length; i < n; i++) {
             var expectedEntry = expectedEntries[i];
 
-            if (expectedEntry.class === undefined) {
-                assert.equal(result.finalEndOfLineState, expectedEntry.value, "final endOfLineState does not match expected.");
+            if (expectedEntry.classification === undefined) {
+                assert.equal(result.finalLexState, expectedEntry.value, "final endOfLineState does not match expected.");
             }
             else {
                 var actualEntryPosition = text.indexOf(expectedEntry.value);
@@ -87,7 +50,7 @@ describe('Colorization', function () {
                 var actualEntry = getEntryAtPosistion(result, actualEntryPosition);
 
                 assert(actualEntry, "Could not find classification entry for '" + expectedEntry.value + "' at position: " + actualEntryPosition);
-                assert.equal(actualEntry.class, expectedEntry.class, "Classification class does not match expected. Expected: " + ts.TokenClass[expectedEntry.class] + ", Actual: " + ts.TokenClass[actualEntry.class]);
+                assert.equal(actualEntry.classification, expectedEntry.classification, "Classification class does not match expected. Expected: " + ts.TokenClass[expectedEntry.classification] + ", Actual: " + ts.TokenClass[actualEntry.classification]);
                 assert.equal(actualEntry.length, expectedEntry.value.length, "Classification length does not match expected. Expected: " + ts.TokenClass[expectedEntry.value.length] + ", Actual: " + ts.TokenClass[actualEntry.length]);
             }
         }
@@ -320,8 +283,6 @@ describe('Colorization', function () {
         });
 
         it("LexicallyClassifiesConflictTokens", () => {
-            debugger;
-
             // Test conflict markers.
             testLexicalClassification(
 "class C {\r\n\