iOS Unit Testing by Example

Design the Test Case

Now we can try using our test spy to test the app. Let’s start by adding a test suite ViewControllerTests. Use Test Zero as temporary scaffolding to confirm that you hooked up the test suite. (See ​Start from Test Zero​.) Delete Test Zero once you see its expected failure message.

Let’s test that tapping the button creates a data task with the expected request. Think for a moment about how to set up the test and how to confirm the result. We want to do the following:

• Instantiate the view controller from the storyboard.

• Create an instance of MockURLSession.

• Inject the MockURLSession into the view controller. Following what we learned in ​Test UserDefaults​, let’s make sure to do this before loading the view. We do ...