mockReturnValue overwrites mockImplementation

[aaronabramov]

  test('mockImplementation && mockReturnValue', () => {
    const fn = jest.fn();
    expect(fn()).toBeUndefined();
    fn.mockReturnValue('returnValue');
    fn.mockImplementation(() => 'foo');
    expect(fn()).toBe('foo'); // fails because: fn() => 'returnValue'
  });

i'm not sure if this is expected or not. The behavior was different in jest@19

[github-actions]

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.
Please note this issue tracker is not a help forum. We recommend using StackOverflow or our discord channel for questions.