title: How does one unit test network-dependent operations?
body: <p>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. </p>
  
  <p>What's a valid way to test data that "lies on the other end of a web request"? </p>
  
  <p>I'm using the stock unit testing toolkit that comes with Xcode, but the question theoretically applies to any testing framework.</p>