xcode - 使用通知的设计的单元测试

Question

我在测试一些使用通知的逻辑时遇到了困难。我读过 enforcing that particular NSNotifications are sent ，但这并不能真正解决我看到的问题。
[SomeObject PerformAsyncOperation]创建一个 NSURLRequest并将自己设置为响应委托(delegate)。根据响应的内容，SomeObject发布成功或失败NSNotification为默认 NSNotificationCenter .

我的测试的问题是在 PerformAsyncOperation 之后被调用时，测试不会等待发送响应。相反，它继续断言 - 失败，因为请求/响应没有时间发送/接收/解析。

这是代码:

-(void)testMethod {
    SomeObject *x = [[SomeObject alloc] init];

    [[NSNotificationCenter defaultCenter] addObserver:self
                                        selector:@selector(success:)
                                            name:SomeObjectSuccess
                                          object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                        selector:@selector(failure:)
                                            name:SomeObjectFailure
                                          object:nil];

    operationCompleted = false; // declared in .h

    [x PerformAsyncOperation:@"parameter"];

    STAssertTrue(operationCompleted , @"Operation has completed.");

    [[NSNotificationCenter defaultCenter] removeObserver:self name:SomeObjectSuccess object:nil];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:SomeObjectFailure object:nil];

    [x release];
}

-(void) failure:(NSNotification *) notification {
   operationCompleted = true;
   NSLog(@"Received failure message.");
}

-(void) success:(NSNotification *) notification {
   operationCompleted = true;
   NSLog(@"Received success message.");
}

我尝试在调用 PerformAsyncOperation 后让线程休眠，以及一个空的 while (!operationCompleted)环形。两者都不起作用 - 休眠线程仍然使断言失败，并且 while 循环永远不会退出。我还尝试将断言移入 success:和 failure: ，但是因为 OCUnit 期望每个方法都是测试方法，所以它只是立即执行所有三个方法并退出(无需等待 NSURLRequest 的响应，这就是练习的重点!)。

任何想法或见解将不胜感激。谢谢!

Answer 1

您面临的问题不是通知，而是同步的。相反，您正在触发异步操作。要使这是一个可重复的测试，您需要重新同步事物。

NSTimeInterval timeout = 2.0;   // Number of seconds before giving up
NSTimeInterval idle = 0.01;     // Number of seconds to pause within loop
BOOL timedOut = NO;

NSDate *timeoutDate = [[NSDate alloc] initWithTimeIntervalSinceNow:timeout];
while (!timedOut && !operationCompleted)
{
    NSDate *tick = [[NSDate alloc] initWithTimeIntervalSinceNow:idle];
    [[NSRunLoop currentRunLoop] runUntilDate:tick];
    timedOut = ([tick compare:timeoutDate] == NSOrderedDescending);
    [tick release];
}
[timeoutDate release];

超过这一点，您就知道操作已完成，或者测试已超时。