convertFunctionToEs6Class: Copy comment from variable declaration (#23445)

Author: Andy

src/services/codefixes/convertFunctionToEs6Class.ts

@@ -34,13 +34,14 @@ namespace ts.codefix {
 
             case SyntaxKind.VariableDeclaration:
                 precedingNode = ctorDeclaration.parent.parent;
+                newClassDeclaration = createClassFromVariableDeclaration(ctorDeclaration as VariableDeclaration);
                 if ((<VariableDeclarationList>ctorDeclaration.parent).declarations.length === 1) {
+                    copyComments(precedingNode, newClassDeclaration, sourceFile);
                     deleteNode(precedingNode);
                 }
                 else {
                     deleteNode(ctorDeclaration, /*inList*/ true);
                 }
-                newClassDeclaration = createClassFromVariableDeclaration(ctorDeclaration as VariableDeclaration);
                 break;
         }
 

tests/cases/fourslash/convertFunctionToEs6Class_commentOnVariableDeclaration.ts

@@ -0,0 +1,16 @@
+/// <reference path='fourslash.ts' />
+
+// @allowJs: true
+// @Filename: /a.js
+/////** Doc */
+////const C = function() { this.x = 0; }
+
+verify.codeFix({
+    description: "Convert function to an ES2015 class",
+    newFileContent:
+`/** Doc */
+class C {
+    constructor() { this.x = 0; }
+}
+`,
+});