test_runner: support typescript module mocking

Author: marco-ippolito

lib/internal/modules/esm/translators.js

@@ -478,7 +478,7 @@ translators.set('wasm', async function(url, source) {
 // Strategy for loading a commonjs TypeScript module
 translators.set('commonjs-typescript', function(url, source) {
   emitExperimentalWarning('Type Stripping');
-  assertBufferSource(source, false, 'load');
+  assertBufferSource(source, true, 'load');
   const code = stripTypeScriptTypes(stringify(source), url);
   debug(`Translating TypeScript ${url}`);
   return FunctionPrototypeCall(translators.get('commonjs'), this, url, code, false);
@@ -487,7 +487,7 @@ translators.set('commonjs-typescript', function(url, source) {
 // Strategy for loading an esm TypeScript module
 translators.set('module-typescript', function(url, source) {
   emitExperimentalWarning('Type Stripping');
-  assertBufferSource(source, false, 'load');
+  assertBufferSource(source, true, 'load');
   const code = stripTypeScriptTypes(stringify(source), url);
   debug(`Translating TypeScript ${url}`);
   return FunctionPrototypeCall(translators.get('module'), this, url, code, false);

lib/internal/test_runner/mock/loader.js

@@ -137,7 +137,7 @@ async function load(url, context, nextLoad) {
 async function createSourceFromMock(mock, format) {
   // Create mock implementation from provided exports.
   const { exportNames, hasDefaultExport, url } = mock;
-  const useESM = format === 'module';
+  const useESM = format === 'module' || format === 'module-typescript';
   const source = `${testImportSource(useESM)}
 if (!$__test.mock._mockExports.has('${url}')) {
   throw new Error(${JSONStringify(`mock exports not found for "${url}"`)});

lib/internal/test_runner/mock/mock.js

@@ -70,7 +70,7 @@ const kMockUnknownMessage = 3;
 const kWaitTimeout = 5_000;
 const kBadExportsMessage = 'Cannot create mock because named exports ' +
   'cannot be applied to the provided default export.';
-const kSupportedFormats = ['builtin', 'commonjs', 'module'];
+const kSupportedFormats = ['builtin', 'commonjs', 'module', 'module-typescript', 'commonjs-typescript'];
 let sharedModuleState;
 
 class MockFunctionContext {
@@ -517,7 +517,10 @@ class MockTracker {
 
     // Get the file that called this function. We need four stack frames:
     // vm context -> getStructuredStack() -> this function -> actual caller.
-    const caller = pathToFileURL(getStructuredStack()[3]?.getFileName()).href;
+    const filename = getStructuredStack()[3]?.getFileName();
+    // If the caller is already a file URL, use it as is. Otherwise, convert it.
+    const hasFileProtocol = StringPrototypeStartsWith(filename, 'file://');
+    const caller = hasFileProtocol ? filename : pathToFileURL(filename).href;
     const { format, url } = sharedState.moduleLoader.resolveSync(
       mockSpecifier, caller, null,
     );

test/es-module/test-typescript.mjs

@@ -324,3 +324,17 @@ test('execute a JavaScript file importing a cjs TypeScript file', async () => {
   match(result.stdout, /Hello, TypeScript!/);
   strictEqual(result.code, 0);
 });
+
+test('execute a TypeScript test mocking module', async () => {
+  const result = await spawnPromisified(process.execPath, [
+    '--test',
+    '--experimental-test-module-mocks',
+    '--experimental-strip-types',
+    '--no-warnings',
+    fixtures.path('typescript/ts/test-mock-module.ts'),
+  ]);
+  strictEqual(result.stderr, '');
+  match(result.stdout, /Hello, TypeScript-Module!/);
+  match(result.stdout, /Hello, TypeScript-CommonJS!/);
+  strictEqual(result.code, 0);
+});

test/fixtures/typescript/ts/commonjs-logger.ts

@@ -0,0 +1,5 @@
+const logger = (): void => { };
+
+module.exports = {
+    logger
+}

test/fixtures/typescript/ts/module-logger.ts

@@ -0,0 +1 @@
+export const logger = (): void => { };

test/fixtures/typescript/ts/test-mock-module.ts

@@ -0,0 +1,24 @@
+import { before, mock, test } from 'node:test';
+import { strictEqual } from 'node:assert';
+
+const logger = mock.fn((s) => console.log(`Hello, ${s}!`));
+
+before(async () => {
+    mock.module('./module-logger.ts', {
+        namedExports: { logger }
+    });
+    mock.module('./commonjs-logger.ts', {
+        namedExports: { logger }
+    });
+});
+
+test('logger', async () => {
+
+    const { logger: mockedModule} = await import('./module-logger.ts');
+    mockedModule('TypeScript-Module');
+    strictEqual(logger.mock.callCount(), 1);
+
+    const { logger: mockedCommonjs } = await import('./commonjs-logger.ts');
+    mockedCommonjs('TypeScript-CommonJS');
+    strictEqual(logger.mock.callCount(), 2);
+});