Cannot mock virtual module inside test or describe [Bug]:

[nihil-pro]

Version

27.4.5

Steps to reproduce

When i try to mock a module that is virtual (using webpack module federation), it works only on top level.

this works well

jest.mock('SomeModule', () => ({
...
}), { virtual: true })

test('', () => {
...
})

this doesn't with error Cannot find module 'SomeModule'

test('', () => {
    jest.mock('SomeModule', () => ({
        ...
    }), { virtual: true })
    
    ...
})

Expected behavior

This should work fine

test('', () => {
    jest.mock('SomeModule', () => ({
        ...
    }), { virtual: true })
    
    ...
})

Actual behavior

Test suit filed to run
Cannot find module

Additional context

No response

Environment

Node 14.17
NPM 6.14
OS Windows 10 10.0.1
CPU (10) x64 Intel(R) Xeon(R) Gold 6240 CPU @ 2.60GHz
jest 27.4.5

[F3n67u]

@nihil-pro thanks for the report. could you provide a repro repo😀?

[nihil-pro]

Sure

https://github.com/nihil-pro/test.git

install dependencies and then run test
there are two tests, one where mock are inside the test, and one where mock are outside.
the second will pass successful

[F3n67u]

The problem is the mock which inside the test is not hoisted to top the code, in other words, it's not hoisted before the ./Main import which makes the mock is not take effect.

Compiled result of MockInside.test.jsx, jest.mock is not hoisted before require('./Main'):

var _interopRequireDefault = require("/workspace/test/node_modules/@babel/runtime/helpers/interopRequireDefault.js").default;

var _react = _interopRequireDefault(require("react"));

var _react2 = require("@testing-library/react");

var _Main = require("./Main");

var _jsxDevRuntime = require("react/jsx-dev-runtime");

var _jsxFileName = "/workspace/test/src/components/MockInside.test.jsx";

function _getJestObj() {
  const {
    jest
  } = require("@jest/globals");

  _getJestObj = () => jest;

  return jest;
}

test('App with data', () => {
  _getJestObj().mock('remoteService', () => ({
    get: jest.fn(async () => {
      return [{
        id: 1,
        title: 'title'
      }];
    })
  }), {
    virtual: true
  });

  (0, _react2.render)( /*#__PURE__*/(0, _jsxDevRuntime.jsxDEV)(_Main.Main, {}, void 0, false, {
    fileName: _jsxFileName,
    lineNumber: 13,
    columnNumber: 10
  }, void 0));

  const posts = _react2.screen.getByTestId('posts');

  expect(posts).toBeInTheDocument();
  (0, _react2.cleanup)();
});
test('App without data', () => {
  _getJestObj().mock('remoteService', () => ({
    get: jest.fn(async () => {
      return null;
    })
  }), {
    virtual: true
  });

  (0, _react2.render)( /*#__PURE__*/(0, _jsxDevRuntime.jsxDEV)(_Main.Main, {}, void 0, false, {
    fileName: _jsxFileName,
    lineNumber: 27,
    columnNumber: 10
  }, void 0));

  const skeleton = _react2.screen.getByTestId('skeleton');

  expect(skeleton).toBeInTheDocument();
  (0, _react2.cleanup)();
});

Compiled result of MockInside.test.jsx, jest.mock is hoisted before require('./Main'):

_getJestObj().mock('remoteService', () => ({
  get: jest.fn(async () => {
    return [{
      id: 1,
      title: 'title'
    }];
  })
}), {
  virtual: true
});

var _interopRequireDefault = require("/workspace/test/node_modules/@babel/runtime/helpers/interopRequireDefault.js").default;

var _react = _interopRequireDefault(require("react"));

var _react2 = require("@testing-library/react");

var _Main = require("./Main");

var _jsxDevRuntime = require("react/jsx-dev-runtime");

var _jsxFileName = "/workspace/test/src/components/MockOutside.test.jsx";

function _getJestObj() {
  const {
    jest
  } = require("@jest/globals");

  _getJestObj = () => jest;

  return jest;
}

test('App with data', () => {
  (0, _react2.render)( /*#__PURE__*/(0, _jsxDevRuntime.jsxDEV)(_Main.Main, {}, void 0, false, {
    fileName: _jsxFileName,
    lineNumber: 12,
    columnNumber: 10
  }, void 0));

  const posts = _react2.screen.getByTestId('posts');

  expect(posts).toBeInTheDocument();
  (0, _react2.cleanup)();
});

[F3n67u]

@nihil-pro It's related to #2582. It seems jest.mock doesn't work inside a test is a known issue for jest. maybe you can find some workaround at #2582.

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