How to test UIViewControllers at build time?

Question

I'm a big believer in testing, but not a very good practitioner. I've done pretty well at getting coverage on my model objects and programming them in a TDD style. I'm actually enjoying it so much I'd love to extend this to my controller layer, particularly my UIViewController subclasses.

Unfortunately, many UIKit classes don't function in independent tests. However, I'm unhappy with the restriction of only running my dependent tests on the device. It's really important to me to run all unit tests before every build, and it seems to me like its possible and worthwhile to unit test (as opposed to other types of testing) controller code.

My question is simply this: How do I test UIViewControllers in such a way that the tests run before every build? I am aware of a couple of different solutions to this problem, but don't know a whole lot about the various benefits of each one.

Answer 1

In general if you are stuck with an environmental problem where unconditional testing seems to be made impossible, you can work around it if the benefits are great enough to warrant your jumping through some hoops.

The situation here is a special case of unwanted outside dependencies, which I generally solve in my unit tests by either #ifdefing out tiny bits of dependent code, or by implementing stub classes to fill the expected dependency roles enough that my code can be tested.

So in this specific case, you might create a new source file, linked only in the test bundle, called "UIKitStubClasses.m" … within it you could implement the bare necessities to simulate UIKit dependent classes such as UIViewController, so that your tests link and thoroughly exercise their own logic.

The important thing to remember is this is usually not necessarily all that much work. The tests will let you know what you need to implement in the stub, for example by issuing exceptions about unimplemented methods. You just add what you need to quiet the errors and test your code, and then your stub class is as sufficient for testing as any of the legitimate system framework classes would be.

Answer 2

Can you not use the tips/methods in Chris Hanson's blog here: http://chanson.livejournal.com/120263.html

It seems that you would probably need to run your app as the test harness, but it seems doable. Just because you are running the 'app' doesn't mean it necessarily has to do the normal thing your application does. Alternatively, you could create another application target that is just a simple dummy application that will load your test bundles and run them.

I agree it might not be perfect, but it sounds like it might work, and it seems like it could be automated.

Answer 3

So I was unhappy with this situation as it stood, and both Daniel and Ed's answers spurred me on to improve things further. I decided to take matters into my own hands.

What I ended up writing was a small Cocoa Touch application that in -applicationDidFinishLaunching scans the class hierarchy for any SenTestCase subclasses and runs them. Unlike GoogleToolboxForMac's unit testing stuff, I tried to use as much of the built in SenTesting machinery as possible and as a result it didn't really end up as that much code. I haven't done too much testing beyond verifying that UILabel allocates without crashing the test rig (otest does in fact crash if you try), but it should work.

I've put the source online on both Bitbucket and Github.