Testing asynchronous call in unit test in iOS

Question

I am facing a problem while unit testing an asynchronous call in iOS. (Although it is working fine in view controllers.)

Has anyone faced this issue before? I have t

Answer 1

If you are using XCode 6, you can test async network calls like this:

XCTest and asynchronous testing in Xcode 6

Answer 2

I think many of the suggested solutions in this post has the problem that if the asynchronous operation does not complete the "done" flag is never set, and the test will hang forever.

I have successfully used this approach in many of my test.

- (void)testSomething {
    __block BOOL done = NO;

    [obj asyncMethodUnderTestWithCompletionBlock:^{
        done = YES;
    }];

    XCTAssertTrue([self waitFor:&done timeout:2],
                   @"Timed out waiting for response asynch method completion");
}


- (BOOL)waitFor:(BOOL *)flag timeout:(NSTimeInterval)timeoutSecs {
    NSDate *timeoutDate = [NSDate dateWithTimeIntervalSinceNow:timeoutSecs];

    do {
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:timeoutDate];
        if ([timeoutDate timeIntervalSinceNow] < 0.0) {
            break;
        }
    }
    while (!*flag);
    return *flag;
}

Answer 3

AGAsyncTestHelper is a C macro for writing unit tests with asynchronous operations and works with both SenTestingKit and XCTest.

Simple and to the point

- (void)testAsyncBlockCallback
{
    __block BOOL jobDone = NO;

    [Manager doSomeOperationOnDone:^(id data) {
        jobDone = YES; 
    }];

    WAIT_WHILE(!jobDone, 2.0);
}

Answer 4

you can use async api calling in swift like this

private let serverCommunicationManager : ServerCommunicationManager = {
    let instance = ServerCommunicationManager()
    return instance
}()

var expectation:XCTestExpectation?
func testAsyncApiCall()  {
    expectation = self.expectation(description: "async request")

    let header = ["Authorization":"eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImp0aSI6ImQ4MmY1MTcxNzI4YTA5MjI3NWIzYWI3OWNkOTZjMGExOTI4MmM2NDEyZjMyYWQzM2ZjMzY4NmU2MjlhOWY2YWY1NGE0MDI4MmZiNzY2NWQ3In0.eyJhdWQiOiIxIiwianRpIjoiZDgyZjUxNzE3MjhhMDkyMjc1YjNhYjc5Y2Q5NmMwYTE5MjgyYzY0MTJmMzJhZDMzZmMzNjg2ZTYyOWE5ZjZhZjU0YTQwMjgyZmI3NjY1ZDciLCJpYXQiOjE1MDg4MjU1NTEsIm5iZiI6MTUwODgyNTU1MSwiZXhwIjoxNTQwMzYxNTUxLCJzdWIiOiIiLCJzY29wZXMiOltdfQ.osoMQgiY7TY7fFrh5r9JRQLQ6AZhIuEbrIvghF0VH4wmkqRUE6oZWjE5l0jx1ZpXsaYUhci6EDngnSTqs1tZwFTQ3srWxdXns2R1hRWUFkAN0ri32W0apywY6BrahdtiVZa9LQloD1VRMT1_QUnljMXKsLX36gXUsNGU6Bov689-bCbugK6RC3n4LjFRqJ3zD9gvkRaODuOQkqsNlS50b5tLm8AD5aIB4jYv3WQ4-1L74xXU0ZyBTAsLs8LOwvLB_2B9Qdm8XMP118h7A_ddLo9Cyw-WqiCZzeZPNcCvjymNK8cfli5_LZBOyjZT06v8mMqg3zszWzP6jOxuL9H1JjBF7WrPpz23m7dhEwa0a-t3q05tc1RQRUb16W1WhbRJi1ufdMa29uyhX8w_f4fmWdAnBeHZ960kjCss98FA73o0JP5F0GVsHbyCMO-0GOHxow3-BqyPOsmcDrI4ay006fd-TJk52Gol0GteDgdntvTMIrMCdG2jw8rfosV6BgoJAeRbqvvCpJ4OTj6DwQnV-diKoaHdQ8vHKe-4X7hbYn_Bdfl52gMdteb3_ielcVXIaHmQ-Dw3E2LSVt_cSt4tAHy3OCd7WORDY8uek4Paw8Pof0OiuqQ0EB40xX5hlYqZ7P_tXpm-W-8ucrIIxgpZb0uh-wC3EzBGPjpPD2j9CDo"]
    serverCommunicationManager.sendServerRequest(httpMethodType: .get, baseURL: "http://192.168.2.132:8000/api/v1/user-role-by-company-id/2", param: nil, header: header) { (isSuccess, msg , response) in
        if isSuccess
        {
            let array = response as! NSArray

            if  array.count == 8
            {
                XCTAssertTrue(true)
                self.expectation?.fulfill()
            }
            else
            {
                XCTAssertFalse(false)
                XCTFail("array count fail")
            }
        }
    }
    waitForExpectations(timeout: 5) { (error) in
        if let error = error{
            XCTFail("waiting with error: \(error.localizedDescription)")
        }
    }
}

Answer 5

Here is Apple's description of native support for async testing.

TL;DR manual:

Look at XCTextCase+AsynchronousTesting.h

There is special class XCTestExpectation with only one public method: - (void)fulfill;

You should init instance of this class and in success case call fulfill method. Otherwise your test will fail after timeout that you specify in that method:

- (void)waitForExpectationsWithTimeout:(NSTimeInterval)timeout handler:(XCWaitCompletionHandler)handlerOrNil;

Example:

- (void)testAsyncMethod
{

    //Expectation
    XCTestExpectation *expectation = [self expectationWithDescription:@"Testing Async Method Works Correctly!"];

    [MyClass asyncMethodWithCompletionBlock:^(NSError *error) {        
        if(error)
            NSLog(@"error is: %@", error);
        else
            [expectation fulfill];
    }];

    //Wait 1 second for fulfill method called, otherwise fail:    
    [self waitForExpectationsWithTimeout:1 handler:^(NSError *error) {

        if(error)
        {
            XCTFail(@"Expectation Failed with error: %@", error);
        }

    }];
}

Answer 6

I suggest you should have a look on the tests of Facebook-ios-sdk. It's a good example of how to test async unit test on iOS, though personally I think async tests should be break into sync tests.

FBTestBlocker: a blocker that prevent current thread exits with specified timeout. You can drag and drop this to your project, but you need to remove OCMock related stuff if you don't have that in you project.

FBTestBlocker.h

FBTestBlocker.m

FBURLConnectionTests: test examples you should look at.

FBURLConnectionTests.h

FBURLConnectionTests.m

This code snippet should give you some idea

- (void)testExample
{
    FBTestBlocker *_blocker = [[FBTestBlocker alloc] initWithExpectedSignalCount:1];
    __block BOOL excuted = NO;
    [testcase test:^(BOOL testResult) {
        XCTAssert(testResult, @"Should be true");
        excuted = YES;
        [_blocker signal];
    }];

    [_blocker waitWithTimeout:4];
    XCTAssertTrue(excuted, @"Not executed");
}