How do You Really Mock Objects You Don't Own? You Replace Them with Adapters
How do you test NSURLSession properly? After all, using it in tests directly will hit the servers; that’s not what you want to do 1000s of times per day. Even if you use a localhost based server replacement the tests will be slower and potentially error-prone as the server replacement may not be 100% accurate. Anyway – there’s a popular series of posts about that topic. There, you’ll learn how to mock NSURLSession in your tests. I think the advice is good to move on quickly, but it only shifts the problem slightly out of sight. There are better alternatives.