在什么情况下会在快速测试中使用ExpectationForNotification

问题描述

我对何时使用expectationForNotification as opposed to expectationWithDescription`感到困惑.我一直无法迅速找到任何清晰的示例来说明此调用的时间和作用.

I'm a little confused as what/when to do with expectationForNotification as opposed toexpectationWithDescription`. I've been unable to find any clear examples in swift for when and what you do with this call.

我假设它也许可以测试通知，但是看起来它可能是通知中心整个addObserver()调用的一个更方便的包装.

I'm assuming its perhaps to test notifications but it looks like it might just be a more convenient wrapper around the whole addObserver() call of notification center.

有人可以简要解释一下它的功能，何时使用以及几行示例代码吗?

Could somebody give a brief explanation of what it does, when to use it, and perhaps a few lines of sample code?

推荐答案

正如您已经想到的， expectationForNotification 是检查通知是否已发出的一种方便期望.

As you have already imagined expectationForNotification is a convenience expectation for checking if a notification was raised.

该测试:

func testItShouldRaiseAPassNotificationV1() {
    let expectation = expectationWithDescription("Notification Raised")
    let sub = NSNotificationCenter.defaultCenter().addObserverForName("evPassed", object: nil, queue: nil) { (not) -> Void in
        expectation.fulfill()
    }
    NSNotificationCenter.defaultCenter().postNotificationName("evPassed", object: nil)
    waitForExpectationsWithTimeout(0.1, handler: nil)
    NSNotificationCenter.defaultCenter().removeObserver(sub)
}

可以用以下内容代替:

func testItShouldRaiseAPassNotificationV2() {
    expectationForNotification("evPassed", object: nil, handler: nil)
    NSNotificationCenter.defaultCenter().postNotificationName("evPassed", object: nil)
    waitForExpectationsWithTimeout(0.1, handler: nil)
}

您可以在此 Objc.io号中找到很好的解释.

You can find a good explanation in this Objc.io number.

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