Issue with fs module mock

[mrmckeb]

Describe the bug

When trying to mock fs (or node:fs), I'm only able to mock the return value or mock implementation under certain conditions.

In the below reproduction, switching the order of the two tests actually makes the tests work.

Note that this project is set to ESM, via "type": "module" in package.json.

Reproduction

File:

import { readFileSync } from 'node:fs';

export const readFile = () => {
  try {
    return readFileSync('some-file', 'utf-8');
  } catch (e) {
    return '';
  }
};

Test:

import { readFileSync } from 'node:fs';
import { afterEach, describe, expect, it, vi } from 'vitest';

vi.mock('node:fs', () => ({
  readFileSync: vi.fn().mockImplementation(() => ''),
}));

const mockReadFileSync = vi.mocked(readFileSync);

describe('env', () => {
  afterEach(() => {
    vi.resetModules();
  });

  it('should handle a missing file', async () => {
    mockReadFileSync.mockImplementation(() => {
      throw new Error('Some error');
    });
    const { readFile } = await import('./repro');
    expect(readFile()).toBe('');
  });

  it('should read a file', async () => {
    mockReadFileSync.mockImplementation(() => 'Some contents');
    const { readFile } = await import('./repro');
    expect(readFile()).toBe('Some contents');
  });
});

Config:

import { defineConfig } from 'vitest/config';

export default defineConfig({
  test: {
    mockReset: true,
  },
});

System Info

System:
    OS: macOS 12.4
    CPU: (8) arm64 Apple M1
    Memory: 177.42 MB / 16.00 GB
    Shell: 5.8.1 - /bin/zsh
  Binaries:
    Node: 18.6.0 - ~/Library/Caches/fnm_multishells/11869_1657854968244/bin/node
    npm: 8.13.2 - ~/Library/Caches/fnm_multishells/11869_1657854968244/bin/npm
  Browsers:
    Chrome: 103.0.5060.114
    Edge: 103.0.1264.62
    Firefox: 102.0.1
    Safari: 15.5
  npmPackages:
    vitest: ^0.18.0 => 0.18.0

Used Package Manager

pnpm

Validations

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• Read the Contributing Guidelines.
• Read the docs.
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• The provided reproduction is a minimal reproducible example of the bug.

[sheremet-va]

vi.resetModules removes mocks. This is bug with resetModules, and not with ESM mocking. Importing fs has nothing to do with ESM.

[mrmckeb]

Thank you!