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

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);
        }

    }];
}