iOS Unit Testing by Example

Test Code-Based Modal Presentation

Let’s continue to test code-based navigation, this time moving to modals. The view controller makes a present(_:animated:) call. How can we capture the result of this call?

If we had defined the main view controller outside of a storyboard, there’s a useful trick we could have used. To intercept the call, we could make a test-specific subclass. It would provide its own implementation of the present(_:animated:completion:) method, including the optional completion handler.

Navigation/NavigationTests/ViewControllerTests.swift

// We can't use this for a view controller that comes from a storyboard.
private class TestableViewController: ViewController {
    var presentCallCount = 0
    var presentArgsViewController: ...