[Week 2] isInverted

[hope1053]

궁금한점

isInverted를 왜 사용해야하는지?

• isInverted가 적용된 코드

func testPostDouble_generatesOnlyOneNotification() {
    // given
    let exp = expectation(forNotification: AlertNotification.name, object: sut)
    exp.expectedFulfillmentCount = 2
    exp.isInverted = true
    
    let alert = Alert("this is an alert")
    
    // when
    sut.postAlert(alert: alert)
    sut.postAlert(alert: alert)
    
    // then
    wait(for: [exp], timeout: 1)
  }

• 위 코드를 왜 아래처럼 작성하지 않았는지 궁금 ! 도대체 isInverted를 어떻게 써야 잘 썼다고 들을 수 있을까?

func testPostDouble_generatesOnlyOneNotification() {
    //given
    let exp = expectation(
      forNotification: AlertNotification.name,
      object: sut,
      handler: nil)
    exp.expectedFulfillmentCount = 1
    let alert = Alert("this is an alert")

    // when
    sut.postAlert(alert: alert)
    sut.postAlert(alert: alert)

    // then
    wait(for: [exp], timeout: 1)
  }

찾아본 것

this test fails if the expectation is fulfilled and succeeds if the wait times out
= this test will fail if two notifications are triggered by the two alerts.