tdd-react-component-spec4.js

const props = {
  username: 'theuser',
  password: 'thepass',
  onChange: expect.createSpy(),
  onSignIn: expect.createSpy()
};
const wrapper = shallow(<Login {...props}/>);

it('should trigger onChange when any of the input changes', ()=>{
  wrapper.find('.login__user').simulate('change', { target:{ name: 'username', value: 'asd'} });
  expect(props.onChange).toHaveBeenCalledWith({username: 'asd'});
  props.onChange.reset();

  wrapper.find('.login__password').simulate('change', { target:{ name: 'password', value: 'asd'} });
  expect(props.onChange).toHaveBeenCalledWith({password: 'asd'});
});
it('should call onSignIn with user and password', ()=>{
  wrapper.find('.login__form').simulate('submit', { preventDefault: expect.createSpy() });
  const expected = { username: props.username, password: props.password };
  expect(props.onSignIn).toHaveBeenCalledWith(expected);
});