diff --git a/src/harness/fourslash.ts b/src/harness/fourslash.ts
index c571a7d9f94..01637a7e822 100644
--- a/src/harness/fourslash.ts
+++ b/src/harness/fourslash.ts
@@ -189,6 +189,15 @@ module FourSlash {
         // Whether or not we should format on keystrokes
         public enableFormatting = true;
 
+        // Whether or not to generate .d.ts file
+        public enableDeclaration = false;
+
+        // Whether or not to generate one output javascript file
+        public enableSingleOutputFile = false;
+
+        // Output filename for single-output-file option
+        public singleOutputFilename: string = undefined;
+
         public formatCodeOptions: ts.FormatCodeOptions;
 
         public cancellationToken: TestCancellationToken;
@@ -452,6 +461,48 @@ module FourSlash {
             }
         }
 
+        public verifyEmitOutput(state: ts.EmitOutputResult, filename?: string) {
+            if (this.enableDeclaration) {
+                this.languageServiceShimHost.setCompilationSettings({generateDeclarationFiles: true});
+            }
+
+            if (this.enableSingleOutputFile) {
+                this.languageServiceShimHost.setCompilationSettings({ outFileOption: this.singleOutputFilename });
+            }
+
+            var expectedFilenames:string[] = [];
+            if (filename !== undefined) {
+                expectedFilenames = filename.split(" ");
+            }
+
+            var emit = this.languageService.getEmitOutput(this.activeFile.fileName);
+
+            if (emit.emitOutputResult !== state) {
+                throw new Error("Expected emitOutputResult '" + state + "', but actual emitOutputResult '" + emit.emitOutputResult + "'");
+            }
+
+            var passed = true;
+            if (emit.outputFiles.length > 0) {
+                passed = expectedFilenames.every(expectedFilename => {
+                    return emit.outputFiles.some(outputFile => {
+                        return outputFile.name === expectedFilename;
+                    });
+                });
+            }
+
+            if (!passed) {
+                var errorMessage = "Expected outputFilename '" + filename + "', but actualy outputFilename '";
+                emit.outputFiles.forEach((outputFile, idx, array) => {
+                    errorMessage += outputFile.name;
+                    if (idx !== emit.outputFiles.length - 1) {
+                        errorMessage += " ";
+                    }
+                });
+                errorMessage += "'";
+                throw new Error(errorMessage);
+            }
+        }
+
         public verifyMemberListContains(symbol: string, type?: string, docComment?: string, fullSymbolName?: string, kind?: string) {
             this.scenarioActions.push('<ShowCompletionList />');
             this.scenarioActions.push('<VerifyCompletionContainsItem ItemName="' + symbol + '"/>');
diff --git a/src/harness/harnessLanguageService.ts b/src/harness/harnessLanguageService.ts
index 1a02157d729..e15063204ca 100644
--- a/src/harness/harnessLanguageService.ts
+++ b/src/harness/harnessLanguageService.ts
@@ -135,6 +135,8 @@ module Harness.LanguageService {
 
         private fileNameToScript: ts.Map<ScriptInfo> = {};
 
+        private settings: any = {};
+
         constructor(private cancellationToken: ts.CancellationToken = CancellationToken.None) {
         }
 
@@ -179,6 +181,14 @@ module Harness.LanguageService {
             throw new Error("No script with name '" + fileName + "'");
         }
 
+        public getDefaultLibFilename(): string {
+            return undefined;
+        }
+
+        public getCurrentDirectory(): string {
+            return undefined;
+        }
+
         //////////////////////////////////////////////////////////////////////
         // ILogger implementation
         //
@@ -199,7 +209,7 @@ module Harness.LanguageService {
 
         /// Returns json for Tools.CompilationSettings
         public getCompilationSettings(): string {
-            return JSON.stringify({}); // i.e. default settings
+            return JSON.stringify(this.settings);
         }
 
         public getCancellationToken(): ts.CancellationToken {
@@ -236,6 +246,12 @@ module Harness.LanguageService {
             return this.ls;
         }
 
+        public setCompilationSettings(settings: any) {
+            for (var key in settings) {
+                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);
diff --git a/src/harness/projectsRunner.ts b/src/harness/projectsRunner.ts
index b0f3e939d30..7a5fa51e147 100644
--- a/src/harness/projectsRunner.ts
+++ b/src/harness/projectsRunner.ts
@@ -226,7 +226,7 @@ class ProjectRunner extends RunnerBase {
                     ? filename
                     : ts.normalizeSlashes(testCase.projectRoot) + "/" + ts.normalizeSlashes(filename);
 
-                var diskRelativeName = ts.getRelativePathToDirectoryOrUrl(testCase.projectRoot, diskFileName, getCurrentDirectory(), false);
+                var diskRelativeName = ts.getRelativePathToDirectoryOrUrl(testCase.projectRoot, diskFileName, getCurrentDirectory, false);
                 if (ts.isRootedDiskPath(diskRelativeName) || diskRelativeName.substr(0, 3) === "../") {
                     // If the generated output file recides in the parent folder or is rooted path, 
                     // we need to instead create files that can live in the project reference folder
diff --git a/tests/cases/fourslash/fourslash.ts b/tests/cases/fourslash/fourslash.ts
index b4080d12e2f..91bce54525a 100644
--- a/tests/cases/fourslash/fourslash.ts
+++ b/tests/cases/fourslash/fourslash.ts
@@ -44,6 +44,14 @@ enum TypingFidelity {
     High = FourSlash.TypingFidelity.High
 }
 
+// We have to duplicate EmitOutputResult from Services.ts to expose the enum to getEmitOutput testcases in fourslah
+enum EmitOutputResult {
+        Succeeded,
+        FailedBecauseOfSyntaxErrors,
+        FailedBecauseOfCompilerOptionsErrors,
+        FailedToGenerateDeclarationsBecauseOfSemanticErrors
+}
+
 module FourSlashInterface {
     declare var FourSlash;
 
@@ -255,6 +263,10 @@ module FourSlashInterface {
             FourSlash.currentTestState.verifyEval(expr, value);
         }
 
+        public emitOutput(expectedState: EmitOutputResult, expectedFilename?: string) {
+            FourSlash.currentTestState.verifyEmitOutput(expectedState, expectedFilename);
+        }
+
         public currentLineContentIs(text: string) {
             FourSlash.currentTestState.verifyCurrentLineContent(text);
         }
@@ -431,6 +443,23 @@ module FourSlashInterface {
         public disableFormatting() {
             FourSlash.currentTestState.enableFormatting = false;
         }
+
+        public enableDeclaration() {
+            FourSlash.currentTestState.enableDeclaration = true;
+        }
+
+        public disableDeclaration() {
+            FourSlash.currentTestState.enableDeclaration = false;
+        }
+
+        public enableSingleOutputFile(outputFilename: string) {
+            FourSlash.currentTestState.enableSingleOutputFile = true;
+            FourSlash.currentTestState.singleOutputFilename = outputFilename;
+        }
+
+        public disableSingleOutputFile() {
+            FourSlash.currentTestState.enableSingleOutputFile = false;
+        }
     }
 
     export class debug {