experimental-test-module-mocks with ES imports does not reset mocked modules for tests in the same file

Version

24.4.1

Platform

Microsoft Windows NT 10.0.26100.0 x64

Subsystem

node:test

What steps will reproduce the bug?

// file1: utils/fs-wrapper.js
// Simple wrapper around fs.readFileSync to demonstrate the issue
import { readFileSync } from 'node:fs';

export default function readFile(path: string): string {
    return readFileSync(path, 'utf8');
}

// file2: utils/file-processor.js
// Module that depends on fs-wrapper
import readFile from './fs-wrapper.js';

export default function processFile(path: string): string {
    const content = readFile(path);
    return content.toUpperCase();
}

// file3: test/cache-issue.test.js
// Test demonstrating the ES module cache issue
import { test, describe, beforeEach, mock } from 'node:test';
import assert from 'node:assert/strict';

describe('ES Module Cache Issue with mock.restoreAll()', () => {
    beforeEach(() => {
        mock.restoreAll();
    });

    test('first test - should use mock', async (t) => {
        // Mock the fs-wrapper module
        const mockReadFile = mock.fn(() => 'mocked content from test 1');
        t.mock.module('../utils/fs-wrapper.js', {
            defaultExport: mockReadFile,
        });

        // Import the module that depends on fs-wrapper
        const fileProcessorModule = await import('../utils/file-processor.js');
        const processFile = fileProcessorModule.default;

        const result = processFile('dummy-path.txt');

        assert.strictEqual(result, 'MOCKED CONTENT FROM TEST 1');
        assert.strictEqual(mockReadFile.mock.callCount(), 1);
    });

    test('second test - should use different mock but fails due to cache', async (t) => {
        // Mock with different return value
        const mockReadFile = mock.fn(() => 'mocked content from test 2');
        t.mock.module('../utils/fs-wrapper.js', {
            defaultExport: mockReadFile,
        });

        // This import returns cached version that still references the old mock
        const fileProcessorModule = await import('../utils/file-processor.js');
        const processFile = fileProcessorModule.default;

        const result = processFile('dummy-path.txt');

        // This assertion will fail because the cached module still uses the old mock
        assert.strictEqual(result, 'MOCKED CONTENT FROM TEST 2');
        assert.strictEqual(mockReadFile.mock.callCount(), 1);
    });

    test('third test - workaround with cache busting', async (t) => {
        // Mock with third return value
        const mockReadFile = mock.fn(() => 'mocked content from test 3');
        t.mock.module('../utils/fs-wrapper.js', {
            defaultExport: mockReadFile,
        });

        // Use cache busting query parameter to force fresh import
        const fileProcessorModule = await import('../utils/file-processor.js?v=' + Date.now());
        const processFile = fileProcessorModule.default;

        const result = processFile('dummy-path.txt');

        // This assertion passes because we bypassed the cache
        assert.strictEqual(result, 'MOCKED CONTENT FROM TEST 3');
        assert.strictEqual(mockReadFile.mock.callCount(), 1);
    });
});

// Command line: node --test --experimental-test-module-mocks

How often does it reproduce? Is there a required condition?

Every time.

What is the expected behavior? Why is that the expected behavior?

The mocked module should reset between tests.

What do you see instead?

▶ ES Module Cache Issue with mock.restoreAll()
  ✔ first test - should use mock (43.5241ms)
  ✖ second test - should use different mock but fails due to cache (3.0297ms)
  ✔ third test - workaround with cache busting (4.2197ms)
✖ ES Module Cache Issue with mock.restoreAll() (52.1751ms)
ℹ tests 6
ℹ suites 1
ℹ pass 5
ℹ fail 1
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 137.1057

✖ failing tests:

test at dist\tests\file-processor.test.js:22:5
✖ second test - should use different mock but fails due to cache (3.0297ms)
  AssertionError [ERR_ASSERTION]: Expected values to be strictly equal:
  actual expected

      at TestContext.<anonymous> (file:///C:/Users/xxx/Documents/GitHub/genesys-concepts/dist/tests/file-processor.test.js:34:16)
      at async Test.run (node:internal/test_runner/test:1069:7)
      at async Suite.processPendingSubtests (node:internal/test_runner/test:752:7) {
    generatedMessage: true,
    code: 'ERR_ASSERTION',
    actual: 'MOCKED CONTENT FROM TEST 1',
    expected: 'MOCKED CONTENT FROM TEST 2',
    operator: 'strictEqual'
  }

Additional information

Not sure if there is a better workaround for this or maybe I'm doing something wrong?

首先使用 node --test --experimental-test-module-mocks 运行 test/cache-issue.test.js 中的复现。阅读 t.mock.module() 和 mock.restoreAll() 所验证的 node:test 模块 mock 行为，以及 file-processor.js 和 fs-wrapper.js 的导入。完成的标准是第二个测试在没有缓存清除查询参数的情况下获得自己的 mock，同时现有测试继续通过。