ios - 使用 Kiwi 测试核心数据实体的后台保存

Question

我正在努力找出在后台线程中测试与 Core Data 交互的最佳方法。我有以下类方法:

+ (void)fetchSomeJSON
{
    // Download some json then parse it in the block
    [[AFHTTPClient sharedClient] fetchAllThingsWithCompletion:^(id results, NSError *error) {
        if ([results count] > 0) {

            NSManagedObjectContext *backgroundContext = //... create a new context for background insertion
            dispatch_queue_t background = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0);

            dispatch_async(background, ^{ // If I comment this out, my test runs just fine

                //... insert and update some entities
                for (NSString *str in results) {
                    NSManagedObject *object = //...
                }
            });
        }
    }];
}

我目前正在使用以下 Kiwi 代码测试此方法:

describe(@"MyAction", ^{

    __block void (^completionBlock)(NSArray *array, NSError *error);

    beforeEach(^{
        // Stub the http client
        id mockClient = [AFHTTPClient mock];
        [WRNAPIClient stub:@selector(sharedClient) andReturn:mockClient];

        // capture the block argument
        KWCaptureSpy *spy = [mockClient captureArgument:@selector(fetchAllThingsWithCompletion:) atIndex:0];
        [MyClass fetchSomeJSON]; // Call the method so we can capture the block
        completionBlock = spy.argument;

        // run the completion block 
        completionBlock(@[@"blah"], nil);
    })

    // If I remove the dispatch_async block, this test passes fine. 
    // If I add it in again the test fails, probably because its not waiting
    it(@"should return the right count", ^{
        // entityCount is a block that performs a fetch request count
        NSInteger count = entityCount(moc, @"Task");
        [[theValue(count) should] equal:theValue(4)];
    })

    // This works fine, but obviously I don't want to wait a second
    it(@"should return the right count after waiting for a second", ^{
        sleep(1);
        NSInteger count = entityCount(moc, @"Task");
        [[theValue(count) should] equal:theValue(4)];
    });

};

如果我删除 dispatch_async 行，那么我可以让我的测试快速运行。使用 dispatch_async 时，我可以让我的测试套件运行的唯一方法是在调用完成 block 后 sleep(1)。使用 sleep() 让我觉得我没有以正确的方式接近它。我已经尝试使用 shouldEventually 但这似乎并没有重新获取我的 count 值。

Answer 1

您尝试过这些异步 block 宏吗？

#define TestNeedsToWaitForBlock() __block BOOL blockFinished = NO
#define BlockFinished() blockFinished = YES
#define WaitForBlock() while (CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0, true) && !blockFinished)