Some of my apps grab data from the internet. I'm getting into the habit of writing unit tests, and I suspect that if I write a test for values returned from the internet, I will run into latency and/or reliability problems.
What's a valid way to test data that "lies on the other end of a web request"?
I'm using the stock unit testing toolkit that comes with Xcode, but the question theoretically applies to any testing framework.
I posed this question to the venerable folks on #macdev IRC channel on freenode.net, and I got a few really good answers.
Mike Ash (of mikeash.com) suggests implementing a local web server inside my app. For complex cases, I'd probably do this. However, I'm just using some of the built in initWithContentsOfURL:(NSURL *)url method of NSData.
For simpler cases, mike says an alternate method is to pass base64 encoded dummy data directly to the NSData initializer. (Use data://dummyDataEncodedAsBase64GoesAfterTheDataProtocolThingy.)
Similarly, "alistra" suggests using local file URLs that point to files containing mock data.