在 XCTests 中使用 AFHTTPRequestOperation

Question

我有以下测试用例代码：

- (void)testExample {
    // URL https://api.spotify.com/v1/search?q=album%3AJustified%20artist%3AJustin%20Timberlake&type=album


    dispatch_semaphore_t sem = dispatch_semaphore_create(0);
    [[AFHTTPRequestOperationManager manager] GET:@"https://api.spotify.com/v1/search"
                                      parameters:@{@"q":@"album:Justified artist:Justin Timberlake",
                                                   @"type":@"album"}
                                         success:^(AFHTTPRequestOperation *operation, id responseObject) {
                                             dispatch_semaphore_signal(sem);
                                         } failure:^(AFHTTPRequestOperation *operation, NSError *error) {

                                         }
     ];
    dispatch_semaphore_wait(sem, DISPATCH_TIME_FOREVER);

    // This is an example of a functional test case.
    XCTAssert(YES, @"Pass");
}

我期待测试用例阻塞并等待 http 请求完成。 奇怪的是，即使 url 是有效的，AFHTTPRequestOperation 也永远不会到达成功块。 如果我在 XCTest 之外使用以下代码，则不会发生，将执行成功块。 有没有人见过这个？

Answer 1

几个观察：

1. 您的测试正在冻结，因为 AFNetworking 将其完成块分派到主队列。但是你用dispatch_semaphore_wait 阻塞了主线程，导致死锁。

   您可以通过将管理器的completionQueue 设置为用于测试的全局队列来解决此问题，从而消除由主线程上的信号量引起的死锁：

   - (void)testExample {
       dispatch_semaphore_t sem = dispatch_semaphore_create(0);
   
       AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
   
       manager.completionQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
   
       [manager GET:@"https://api.spotify.com/v1/search" parameters:@{@"q":@"album:Justified artist:Justin Timberlake", @"type":@"album"} success:^(AFHTTPRequestOperation *operation, id responseObject) {
           XCTAssert(YES, @"Pass"); // you might want more rigorous test of results here
   
           dispatch_semaphore_signal(sem);
       } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
           XCTFail(@"%@", error.localizedDescription);
   
           dispatch_semaphore_signal(sem);
       }];
   
       dispatch_semaphore_wait(sem, DISPATCH_TIME_FOREVER);
   }
   

2. 注意，现在人们会使用XCTestExpectation 来执行异步测试。这消除了对信号量的需求，巧合的是，也解决了死锁问题：

   - (void)testExample {
       XCTestExpectation *expectation = [self expectationWithDescription:@"asynchronous request"];
   
       AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
   
       [manager GET:@"https://api.spotify.com/v1/search" parameters:@{@"q":@"album:Justified artist:Justin Timberlake", @"type":@"album"} success:^(AFHTTPRequestOperation *operation, id responseObject) {
           XCTAssert(YES, @"Pass"); // you might want more rigorous test of results here
   
           [expectation fulfill];
       } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
           XCTFail(@"%@", error.localizedDescription);
   
           [expectation fulfill];
       }];
   
       [self waitForExpectationsWithTimeout:30.0 handler:nil];
   }
   

3. 顺便说一句，无论您使用XCTestExpectation 还是信号量，请确保成功和失败块都满足期望/信号量。