Added fourslash tests for standalone and array initialization cases and started implementing them

src/services/codefixes/addMissingConst.ts

@@ -1,6 +1,6 @@
 /* @internal */
 namespace ts.codefix {
-    const fixId = "addMissingConstInForLoop";
+    const fixId = "addMissingConst";
     const errorCodes = [
         Diagnostics.Cannot_find_name_0.code,
         Diagnostics.No_value_exists_in_scope_for_the_shorthand_property_0_Either_declare_one_or_provide_an_initializer.code
@@ -22,12 +22,30 @@ namespace ts.codefix {
     });
 
     function makeChange(changeTracker: textChanges.ChangeTracker, sourceFile: SourceFile, pos: number, fixedNodes?: NodeSet<Node>) {
-        const forInitializer = findAncestor(getTokenAtPosition(sourceFile, pos), node =>
+        const token = getTokenAtPosition(sourceFile, pos);
+
+        const forInitializer = findAncestor(token, node =>
             isForInOrOfStatement(node.parent) ? node.parent.initializer === node
                 : isPossiblyPartOfDestructuring(node) ? false : "quit");
-        if (!forInitializer) return;
-        if (!fixedNodes || fixedNodes.tryAdd(forInitializer)) {
-            changeTracker.insertNodeBefore(sourceFile, forInitializer, createToken(SyntaxKind.ConstKeyword));
+        if (forInitializer) return applyChange(changeTracker, forInitializer, sourceFile, fixedNodes);
+
+        const parent = token.parent;
+        const standaloneInitializer = isExpressionStatement(parent.parent);
+        if (standaloneInitializer) return applyChange(changeTracker, parent, sourceFile, fixedNodes);
+
+        const arrayLiteralInitializer = isArrayLiteralExpression(token.parent);
+        if (arrayLiteralInitializer) {
+            const availableIdentifiers: string[] = []; // TODO: where to get/gather this information from?
+            const noIdentifiersDeclared = parent.forEachChild(node => availableIdentifiers.indexOf(node.getFullText()) < 0);
+            if (!noIdentifiersDeclared) return;
+
+            return applyChange(changeTracker, parent, sourceFile, fixedNodes);
+        }
+    }
+
+    function applyChange(changeTracker: textChanges.ChangeTracker, initializer: Node, sourceFile: SourceFile, fixedNodes?: NodeSet<Node>) {
+        if (!fixedNodes || fixedNodes.tryAdd(initializer)) {
+            changeTracker.insertNodeBefore(sourceFile, initializer, createToken(SyntaxKind.ConstKeyword));
         }
     }
 

src/services/tsconfig.json

@@ -45,7 +45,7 @@
         "codeFixProvider.ts",
         "refactorProvider.ts",
         "codefixes/addConvertToUnknownForNonOverlappingTypes.ts",
-        "codefixes/addMissingConstInForLoop.ts",
+        "codefixes/addMissingConst.ts",
         "codefixes/addMissingInvocationForDecorator.ts",
         "codefixes/addNameToNamelessParameter.ts",
         "codefixes/annotateWithTypeFromJSDoc.ts",

tests/cases/fourslash/codeFixAddMissingConstInForInLoop2.ts

@@ -4,7 +4,7 @@
 ////for (y in []) {}
 
 verify.codeFixAll({
-    fixId: "addMissingConstInForLoop",
+    fixId: "addMissingConst",
     fixAllDescription: "Add 'const' to all unresolved variables",
     newFileContent: 
 `for (const x in []) {}

tests/cases/fourslash/codeFixAddMissingConstInForLoopWithArrayDestructuring2.ts

@@ -4,7 +4,7 @@
 ////for ([x] of [[1,2]]) {}
 
 verify.codeFixAll({
-    fixId: "addMissingConstInForLoop",
+    fixId: "addMissingConst",
     fixAllDescription: "Add 'const' to all unresolved variables",
     newFileContent: 
 `for (const [x, y] of [[1,2]]) {}

tests/cases/fourslash/codeFixAddMissingConstInForLoopWithObjectDestructuring2.ts

@@ -4,7 +4,7 @@
 ////for ({ x } of [{ x: 0 }]) { }
 
 verify.codeFixAll({
-    fixId: "addMissingConstInForLoop",
+    fixId: "addMissingConst",
     fixAllDescription: "Add 'const' to all unresolved variables",
     newFileContent: 
 `for (const { x, y } of [{ x: 0, y: 1 }]) { }

tests/cases/fourslash/codeFixAddMissingConstInForOfLoop2.ts

@@ -4,7 +4,7 @@
 ////for (y of []) {}
 
 verify.codeFixAll({
-    fixId: "addMissingConstInForLoop",
+    fixId: "addMissingConst",
     fixAllDescription: "Add 'const' to all unresolved variables",
     newFileContent: 
 `for (const x of []) {}

tests/cases/fourslash/codeFixAddMissingConstToArrayDestructuring1.ts

@@ -0,0 +1,8 @@
+/// <reference path='fourslash.ts' />
+
+////[x] = [0];
+
+verify.codeFix({
+    description: "Add 'const' to unresolved variable",
+    newFileContent: "const [x] = [0];"
+});

tests/cases/fourslash/codeFixAddMissingConstToArrayDestructuring2.ts

@@ -0,0 +1,9 @@
+/// <reference path='fourslash.ts' />
+
+////[x, y] = [0, 1];
+
+verify.codeFixAll({
+    fixId: "addMissingConst",
+    fixAllDescription: "Add 'const' to all unresolved variables",
+    newFileContent: "const [x, y] = [0, 1];"
+});

tests/cases/fourslash/codeFixAddMissingConstToArrayDestructuring3.ts

@@ -0,0 +1,6 @@
+/// <reference path='fourslash.ts' />
+
+////let x: any;
+////[x, y] = [0, 1];
+
+verify.not.codeFixAvailable();

tests/cases/fourslash/codeFixAddMissingConstToStandaloneIdentifier1.ts

@@ -0,0 +1,8 @@
+/// <reference path='fourslash.ts' />
+
+////x = 0;
+
+verify.codeFix({
+    description: "Add 'const' to unresolved variable",
+    newFileContent: "const x = 0;"
+});

tests/cases/fourslash/codeFixAddMissingConstToStandaloneIdentifier2.ts

@@ -0,0 +1,5 @@
+/// <reference path='fourslash.ts' />
+
+////x = 0, y = 0;
+
+verify.not.codeFixAvailable();