Question

The unit testing environment in Xcode is a bit of a black box to me, but from what I have seen I figure the tests are somehow sticked to the main application and then the whole thing is run, executing the tests instead of the normal app flow.

This is great because it allows me to debug and run the tests both on the Simulator and the real device. (I thought that wasn’t possible, the tests always used to run just on the Simulator, did something change?) But I noticed that during testing the whole app really runs, with all the bells and whistles. This is not really a desirable behaviour, so that I set an environment variable for the Test scheme and if I detect the variable in application:didFinishLaunchingWithOptions: I skip the usual initialization, just put up a dummy window and wait for the test rig to finish.

Is it supposed to work like this? Is there a “standard” way to detect that the app is running just as a host for the test rig? (I’m using the official build of Xcode 4.3, if that matters.)

Answer 1

One option is to stop using the main app as a bundle loader. Instead one can create a bare-bones app (let’s call it TestRunner) that just displays an empty screen and servers as a bundle loader for the test suite:

• Make the testing target depend on the TestRunner.
• Set the Bundle Loader of the testing target to $(BUILT_PRODUCTS_DIR)/TestRunner.app/TestRunner.
• Set the Test Host of the testing target to $(BUNDLE_LOADER).

This adds an extra target to the project, but keeps the main app target independent on tests.