setup.spec.js

const setup = propOverrides => {
  const props = Object.assign({
    completedCount: 0,
    activeCount: 0,
    onClearCompleted: jest.fn(),
  }, propOverrides)

  const wrapper = shallow(<Footer {...props} />)

  return {
    props,
    wrapper,
    clear: wrapper.find('.clear-completed'),
    count: wrapper.find('.todo-count'),
  }
}

describe('count', () => {
  test('when active count 0', () => {
    const { count } = setup({ activeCount: 0 })
    expect(count.text()).toEqual('No items left')
  })

  test('when active count above 0', () => {
    const { count } = setup({ activeCount: 1 })
    expect(count.text()).toEqual('1 item left')
  })
});

❤️