CODE EXAMPLE FOR JAVASCRIPT

mock javascript function

// ---- comp.js ----
import * as React from 'react';
import * as comp from './comp';

export const remove = () => {
  // ...do something
}

export const RemoveButton = (props) => (
  <div onClick={() => comp.remove()}>
    Remove
  </div>
);


// ---- comp.test.js ----
import * as React from 'react';
import { shallow } from 'enzyme';

import * as comp from './comp';

describe('removeButton', () => {
  it('should call remove on click', () => {
    const mock = jest.spyOn(comp, 'remove');
    mock.mockImplementation(() => {});
    const component = shallow(<comp.RemoveButton />);
    component.find('div').simulate('click');
    expect(mock).toHaveBeenCalled();
    mock.mockRestore();
  });
});