Use XCTestExpectation

[fabb]

Using XCTestExpectation makes testing of async functionality possible. There is shouldEventually in Kiwi, but it is not as flexible as XCTestExpectation.
To create a new promise with XCTestExpectation it is necessary to access self which is not possible in Kiwi AFAIK. Any ideas, workarounds.

At the moment I use RXPromise as a workaround, with its runLoopWait method I can wait for the promise to be fulfilled/rejected in a test case. I'd prefer to use XCTestExpectation though.

[fatuhoku]

👍

[sharplet]

Would you mind explaining why you feel that expectFutureValue/shouldEventually is not flexible enough?

[fabb]

Kiwi's shouldEventually polls for the expected value until timeout. In several cases, I want to execute something asynchronously, and when finished (successfully or not), I want to do several checks on it. And if the asynchronous task fails, I want the unit test to fail fast and not wait until timeout.

Consider this example borrowed from NSHipster:

it(@"async test", ^{
    NSURL *URL = [NSURL URLWithString:@"http://nshipster.com/"];
    NSString *description = [NSString stringWithFormat:@"GET %@", URL];
    XCTestExpectation *expectation = [self expectationWithDescription:description];

    NSURLSession *session = [NSURLSession sharedSession];
    __block NSData *pData = nil;
    __block NSURLResponse *pResponse = nil;
    __block NSError *pError = nil;
    NSURLSessionDataTask *task = [session dataTaskWithURL:URL
                                        completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                            pData = data;
                                            pResponse = response;
                                            pError = error;
                                            [expectation fulfill];
                                        }];

    [task resume];

    [self waitForExpectationsWithTimeout:task.originalRequest.timeoutInterval handler:^(NSError *error) {
        [task cancel];
        [[pError should] beNil];
        [[pData shouldNot] beNil];
        [[pResponse shouldNot] beNil];
        [[pResponse should] beKindOfClass:[NSHTTPURLResponse class]];
        [[theValue([(NSHTTPURLResponse *)pResponse statusCode]) should] equal:theValue(200)];
        [[pResponse.URL.absoluteString should] equal:URL.absoluteString];
        [[pResponse.MIMEType should] equal:@"text/html"];
    }];
});

[tsabend]

+1 Running into problems with Kiwi + OHHTPPStub https://github.com/AliSoftware/OHHTTPStubs/wiki/OHHTTPStubs-and-asynchronous-tests

[modocache]

Thanks for the idea, @fabb! This would be cool, and has been discussed on other testing/expectation frameworks: Quick/Nimble#28. My thoughts, echoed in that pull request, is that XCTestExpectation has too many restrictions -- it requires the current XCTestCase to vend expectations, it has very specific usages in mind that don't play well with dynamically generated tests, and so on.

Closing this for now -- we probably don't have the resources to really explore this idea further, even if it was something we wanted.