fix(59558): Implement Interface Quick Fix generates duplicate declarations (#59563)

src/services/codefixes/helpers.ts

@@ -301,6 +301,9 @@ export function addNewNodeForMemberSymbol(
             }
 
             for (const signature of signatures) {
+                if (signature.declaration && (signature.declaration.flags & NodeFlags.Ambient)) {
+                    continue;
+                }
                 // Ensure nodes are fresh so they can have different positions when going through formatting.
                 outputMethod(quotePreference, signature, modifiers, createName(declarationName));
             }

tests/cases/fourslash/codeFixClassImplementInterfaceWithAmbientSignatures1.ts

@@ -0,0 +1,32 @@
+/// <reference path='fourslash.ts' />
+
+// @lib: esnext
+// @target: esnext
+
+// @Filename: /node_modules/@types/node/globals.d.ts
+////export {};
+////declare global {
+////    interface SymbolConstructor {
+////        readonly dispose: unique symbol;
+////    }
+////    interface Disposable {
+////        [Symbol.dispose](): void;
+////    }
+////}
+
+// @Filename: /node_modules/@types/node/index.d.ts
+/////// <reference path="globals.d.ts" />
+
+// @Filename: a.ts
+////class Foo implements Disposable {}
+
+goTo.file("a.ts");
+verify.codeFix({
+    description: "Implement interface 'Disposable'",
+    newFileContent:
+`class Foo implements Disposable {
+    [Symbol.dispose](): void {
+        throw new Error("Method not implemented.");
+    }
+}`
+});

tests/cases/fourslash/codeFixClassImplementInterfaceWithAmbientSignatures2.ts

@@ -0,0 +1,19 @@
+/// <reference path='fourslash.ts' />
+
+////declare class A {
+////    method(): void;
+////}
+////class B implements A {}
+
+verify.codeFix({
+    description: "Implement interface 'A'",
+    newFileContent:
+`declare class A {
+    method(): void;
+}
+class B implements A {
+    method(): void {
+        throw new Error("Method not implemented.");
+    }
+}`
+});

tests/cases/fourslash/codeFixClassImplementInterfaceWithAmbientSignatures3.ts

@@ -0,0 +1,19 @@
+/// <reference path='fourslash.ts' />
+
+////declare abstract class A {
+////    abstract method(): void;
+////}
+////class B implements A {}
+
+verify.codeFix({
+    description: "Implement interface 'A'",
+    newFileContent:
+`declare abstract class A {
+    abstract method(): void;
+}
+class B implements A {
+    method(): void {
+        throw new Error("Method not implemented.");
+    }
+}`
+});