How to mock external module method?

13,397

Solution 1

You have to mock the lib/utils module like this:

import utils from '../../lib/utils';
jest.mock('../../lib/utils', () => ({
  redirect: jest.fn()
}))

it('should redirect if no rights', () => {
  mount(
    <SomeComponent />,
  );
  expect(utils.redirect).toHaveBeenCalledWith();
});

This will replace the module with a mock that just returns {redirect:jest.fn()}. This module is also imported into you test where you then can access the spy for redirect and test on this that it was called with the correct parameter.

Solution 2

This is what I ended up using:

 it('should redirect if no rights', () => {

    // this way we mock only one method: redirectTo
    jest.mock('lib/utils', () => {
      const original = require.requireActual('lib/utils');
      original.default.redirectTo = jest.fn();
      return original;
    });

    const redirectTo = require.requireMock('lib/utils').default.redirectTo;

    mount(
      <SomeComponent />,
    );

    expect(redirectTo).toHaveBeenCalled();
  });
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SM79
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SM79

Updated on June 04, 2022

Comments

  • SM79
    SM79 over 1 year

    I have this module with a function in it:

    const utils = {
      redirectTo(url) {
        if (url) {
          window.location = url;
        }
      },
    };
    
    export default utils;
    

    It is used somewhere in a React component like this:

    import utils from '../../lib/utils';
    
    componentWillUpdate() {
      this.redirectTo('foo')
    }
    

    Now I want to check that the value that redirectTo is called with equals foo.

      it('should redirect if no rights', () => {
        const mockRedirectFn = jest.fn();
        utils.redirectTo = mockRedirectFn;
    
        mount(
          <SomeComponent />,
        );
    
        expect(mockRedirectFn).toBeCalled();
        expect(mockRedirectFn).toBeCalledWith('foo');
        console.log(mockRedirectFn.mock);
        // { calls: [], instances: [] }
      });
    

    Thats what I've got and it does not work. How do I do this?

  • fen1ksss
    fen1ksss over 4 years
    require.requireActual('lib/utils') is exactly what I was looking for