PR comment fixes

1. Add 'export' keyword to variables within the namespace.
2. Omit property creation in the namespace when it exists.
3. Update tests

Signed-off-by: Hana Joo <hanajoo@google.com>

Author: h-joo

src/services/codefixes/fixMissingTypeAnnotationOnExports.ts

@@ -261,8 +261,10 @@ function withChanges<T>(
       const newProperties = []
       for (const symbol of elements) {
         if (!isIdentifierText(symbol.name, program.getCompilerOptions().target)) continue;
+        // If there's an existing variable declaration for this property - skip.
+        if (symbol.valueDeclaration && isVariableDeclaration(symbol.valueDeclaration)) continue;
         newProperties.push(factory.createVariableStatement(
-          /*modifiers*/ undefined,
+          [factory.createModifier(SyntaxKind.ExportKeyword)],
           factory.createVariableDeclarationList(
             [factory.createVariableDeclaration(
               symbol.name,

tests/cases/fourslash/codeFixMissingTypeAnnotationOnExports47-expando-functions-3.ts

@@ -15,8 +15,8 @@ verify.codeFix({
     newFileContent:
 `function foo(): void {}
 declare namespace foo {
-    var x: number;
-    var y: number;
+    export var x: number;
+    export var y: number;
 }
 foo.x = 1;
 foo.y = 1;`

tests/cases/fourslash/codeFixMissingTypeAnnotationOnExports47-expando-functions-4.ts

@@ -0,0 +1,24 @@
+/// <reference path='fourslash.ts'/>
+
+// @isolatedDeclarations: true
+// @declaration: true
+// @lib: es2019
+
+// @Filename: /code.ts
+////function foo(): void {}
+////// cannot name this property because it's an invalid variable name.
+////foo["@bar"] = 42;
+////foo.x = 1;
+
+verify.codeFix({
+  description: "Annotate types of properties expando function in a namespace",
+  index: 0,
+  newFileContent:
+`function foo(): void {}
+declare namespace foo {
+    export var x: number;
+}
+// cannot name this property because it's an invalid variable name.
+foo["@bar"] = 42;
+foo.x = 1;`
+});

tests/cases/fourslash/codeFixMissingTypeAnnotationOnExports47-expando-functions-5.ts

@@ -0,0 +1,30 @@
+/// <reference path='fourslash.ts'/>
+
+// @isolatedDeclarations: true
+// @declaration: true
+// @lib: es2019
+
+// @Filename: /code.ts
+////function foo(): void {}
+////// x already exists, so do not generate code for 'x'
+////foo.x = 1;
+////foo.y = 1;
+////namespace foo {
+////  export let x = 42;
+////}
+
+verify.codeFix({
+  description: "Annotate types of properties expando function in a namespace",
+  index: 0,
+  newFileContent:
+`function foo(): void {}
+declare namespace foo {
+    export var y: number;
+}
+// x already exists, so do not generate code for 'x'
+foo.x = 1;
+foo.y = 1;
+namespace foo {
+  export let x = 42;
+}`
+});