fix(test runner): allow worker-only dynamic imports (#21545)

Fixes #21409.

packages/playwright-test/src/common/compilationCache.ts

@@ -19,7 +19,6 @@ import fs from 'fs';
 import os from 'os';
 import path from 'path';
 import { sourceMapSupport } from '../utilsBundle';
-import { isWorkerProcess } from './globals';
 
 export type MemoryCache = {
   codePath: string;
@@ -67,9 +66,6 @@ export function getFromCompilationCache(filename: string, code: string, moduleUr
   if (cache?.codePath)
     return { cachedCode: fs.readFileSync(cache.codePath, 'utf-8') };
 
-  if (isWorkerProcess())
-    throw new Error('Internal error: unexpected file imported in the worker: ' + filename);
-
   // Then do the disk cache, this cache works between the Playwright Test runs.
   const isModule = !!moduleUrl;
   const cachePath = calculateCachePath(code, filename, isModule);

packages/playwright-test/src/common/transform.ts

@@ -145,7 +145,6 @@ export function js2ts(resolved: string): string | undefined {
 }
 
 export function transformHook(code: string, filename: string, moduleUrl?: string): string {
-  // If we are not TypeScript and there is no applicable preprocessor - bail out.
   const { cachedCode, addToCache } = getFromCompilationCache(filename, code, moduleUrl);
   if (cachedCode)
     return cachedCode;

tests/playwright-test/loader.spec.ts

@@ -663,3 +663,29 @@ test('should complain when one test file imports another', async ({ runInlineTes
   expect(result.exitCode).toBe(1);
   expect(result.output).toContain(`test file "a.test.ts" should not import test file "b.test.ts"`);
 });
+
+test('should support dynamic import', async ({ runInlineTest, nodeVersion }) => {
+  const result = await runInlineTest({
+    'helper.ts': `
+      module.exports.foo = 'foo';
+    `,
+    'a.test.ts': `
+      import { test, expect } from '@playwright/test';
+
+      test('pass', async () => {
+        const { foo } = await import('./helper');
+        expect(foo).toBe('foo');
+      });
+    `,
+    'b.test.ts': `
+      import { test, expect } from '@playwright/test';
+
+      test('pass', async () => {
+        const { foo } = await import('./helper');
+        expect(foo).toBe('foo');
+      });
+    `,
+  }, { workers: 1 });
+  expect(result.passed).toBe(2);
+  expect(result.exitCode).toBe(0);
+});