behaviour.spec.js

describe('clear button', () => {
  test('no clear button when no completed todos', () => {
    const { clear } = setup({ completedCount: 0 })
    expect(clear.exists()).toBe(false)
  })

  test('on click calls onClearCompleted', () => {
    const { clear, props } = setup({ completedCount: 1 })
    expect(clear.text()).toEqual('Clear completed')
    clear.simulate('click')
    expect(props.onClearCompleted).toBeCalledWith()
  })
})