fix(test runner): disregard native typescript execution in Node.js (#35300)

Author: dgozman

packages/playwright/src/transform/esmLoader.ts

@@ -40,12 +40,23 @@ async function resolve(specifier: string, context: { parentURL?: string }, defau
   return result;
 }
 
+// non-js files have undefined
+// some js files have null
+// {module/commonjs}-typescript are changed to {module,commonjs} because we handle typescript ourselves
+const kSupportedFormats = new Map([
+  ['commonjs', 'commonjs'],
+  ['module', 'module'],
+  ['commonjs-typescript', 'commonjs'],
+  ['module-typescript', 'module'],
+  [null, null],
+  [undefined, undefined]
+]);
+
 // Node < 18.6: defaultLoad takes 3 arguments.
 // Node >= 18.6: nextLoad from the chain takes 2 arguments.
 async function load(moduleUrl: string, context: { format?: string }, defaultLoad: Function) {
   // Bail out for wasm, json, etc.
-  // non-js files have context.format === undefined
-  if (context.format !== 'commonjs' && context.format !== 'module' && context.format !== undefined)
+  if (!kSupportedFormats.has(context.format))
     return defaultLoad(moduleUrl, context, defaultLoad);
 
   // Bail for built-in modules.
@@ -67,7 +78,7 @@ async function load(moduleUrl: string, context: { format?: string }, defaultLoad
   // Output format is required, so we determine it manually when unknown.
   // shortCircuit is required by Node >= 18.6 to designate no more loaders should be called.
   return {
-    format: context.format || (fileIsModule(filename) ? 'module' : 'commonjs'),
+    format: kSupportedFormats.get(context.format) || (fileIsModule(filename) ? 'module' : 'commonjs'),
     source: transformed.code,
     shortCircuit: true,
   };

tests/playwright-test/esm.spec.ts

@@ -62,7 +62,7 @@ test('should support import attributes', async ({ runInlineTest }) => {
   expect(result.stdout).toContain('imported value (test): bar');
 });
 
-test('should import esm from ts when package.json has type module in experimental mode', async ({ runInlineTest }) => {
+test('should import esm from ts when package.json has type module', async ({ runInlineTest }) => {
   const result = await runInlineTest({
     'playwright.config.ts': `
       import * as fs from 'fs';
@@ -73,8 +73,10 @@ test('should import esm from ts when package.json has type module in experimenta
       import { foo } from './b.ts';
       import { bar } from './c.js';
       import { qux } from './d.js';
-      import { test, expect } from '@playwright/test';
+      // Make sure to import a type-only Locator below to check that our babel strips it out.
+      import { test, expect, Locator } from '@playwright/test';
       test('check project name', ({}, testInfo) => {
+        const locator: Locator = null!;
         expect(testInfo.project.name).toBe('foo');
         expect(bar).toBe('bar');
         expect(qux).toBe('qux');