A test of a login redux-form with enzyme+mount

LoginForm.enzyme.test.js

import React from 'react';
import { configure } from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';
import { mountWithProviders } from '../../../../helpers/test';
import { LoginForm } from './LoginForm';

configure({ adapter: new Adapter() });

describe('LoginForm Component', () => {
  it('should show username label', () => {
    // WHEN
    const signInFormElement = mountWithProviders(<LoginForm />);
    const usernameLabelElement = signInFormElement.find('[data-testid="label-username"]');

    // THEN
    expect(usernameLabelElement.text()).toEqual('USERNAME');
  });

  it('should show password label', () => {
    // WHEN
    const signInFormElement = mountWithProviders(<LoginForm />);
    const passwordLabelElement = signInFormElement.find('[data-testid="label-password"]');

    // THEN
    expect(passwordLabelElement.text()).toEqual('PASSWORD');
  });

  it('should submit the username and password', () => {
    // GIVEN
    const onSubmitMock = jest.fn();
    const password = 'test';
    const username = '[email protected]';

    // WHEN
    const signInFormElement = mountWithProviders(<LoginForm onSubmit={onSubmitMock}/>);

    const passwordInput = signInFormElement.find('[data-testid="input-password"]');
    const usernameInput = signInFormElement.find('[data-testid="input-username"]');
    const signInSubmitButton = signInFormElement.find('[data-testid="button-sign-in-submit"]');

    passwordInput.simulate('change', { target: { value: password } });
    usernameInput.simulate('change', { target: { value: username } });
    signInSubmitButton.simulate('submit');

    // THEN
    /* 
    onSubmit will be called with 3 parameters but only the first one interests me:
    values : Object
    The field values in the form of { field1: 'value1', field2: 'value2' }.
    https://redux-form.com/8.2.2/docs/api/reduxform.md/#-code-onsubmit-function-code-optional-
    
    a less explicite option:
    expect(onSubmitMock.mock.calls[0][0]).toEqual({username, password});
    */
    expect(onSubmitMock).toHaveBeenCalledWith(
      {username, password},
      expect.any(Function),
      expect.any(Object),
    );
  });

  it('should show a errorMessage message if passed one', () => {
    // GIVEN
    const onSubmitMock = jest.fn();
    const errorMsg = 'errorMessage message';

    // WHEN
    const signInFormElement = mountWithProviders(<LoginForm errorMessage={errorMsg} onSubmit={onSubmitMock}/>);
    const errorMessageElement = signInFormElement.find('[data-testid="error-message"]');

    // THEN
    expect(errorMessageElement.text()).toEqual(errorMsg);
  });
});