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I was using SenTestingKit, the default unit testing framework from Apple, when I found out that it does not support tests that involve asynchronous methods, or blocks.

That’s a waste.

Though there is a workaround using semaphore.

- (void)testBlockMethod {
    dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);

    // Your block method eg. AFNetworking
    NSURL *url = [NSURL URLWithString:@"http://httpbin.org/ip"];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
        NSLog(@"IP Address: %@", [JSON valueForKeyPath:@"origin"]);
        STAssertNotNil(JSON, @"JSON not loaded");
        // Signal that block has completed
        dispatch_semaphore_signal(semaphore);
    } failure:nil];
    [operation start];

    // Run loop
    while (dispatch_semaphore_wait(semaphore, DISPATCH_TIME_NOW))
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode
                                 beforeDate:[NSDate dateWithTimeIntervalSinceNow:10]];
    dispatch_release(semaphore);
}

But if you mind, there are lots of other testing frameworks, eg GHUnit supports asynchronous testing.