Get the name of the unit test class in the ios host application

Question

I am using the standard XCTestCase class to implement and trigger the unit tests together with the host ios application. Is it possible to pass a piece of information from the unit test (XCTestCase subclass) to the host application, and read this information in host's main.m?

XCUIApplication().launchArguments does not work for me. Also putting a value in the build settings is not a solution.

I need to change the behaviour of the host application according to the XCTestCase's subclasses.

The class under the test (subclass of XCTestCase) is affected by the host's App Delegate class. I would like to instantiate a special AppDelegateFake class (in main.m) that will not affect the class under test.

It is possible to detect if the host app is running with a unit test set and instantiate a special fake test app delegate class: https://marcosantadev.com/fake-appdelegate-unit-testing-swift/

BUT in that way I have to use this fake app delegate for ALL tests (XCTestCase's).

Something like this if that would be nice to have in the host app:

let isRunningTests = NSClassFromString("XCTestCaseSubclassXY") != nil

but unfortunately, this is not possible. I also tried to get somehow the instance of XCTestConfiguration, which contains the running XCTestCase name, but again it is not possible.

Thanks.

Answer 1

In principle, it is not possible, what I have asked for. For the unit testing, there is a single instance of the running host app. On the other hand for the UI tests, there is every time a dedicated app instance loaded - and configurable with XCUIApplication().launchArguments

Answer 2

I normally include a TestingAppDelegate with my tests. When unit tests run, they are injected into the running app before launch. So the production code can check for the existence of TestingAppDelegate and decide which app delegate to use.

With my use case of having a single replacement app delegate, I do the following in main.swift:

let appDelegateClass: AnyClass =
    NSClassFromString("TestingAppDelegate") ?? AppDelegate.self

This searches for a class with the given name, and uses it if present. Otherwise, it falls back to the regular production code AppDelegate. Then I use this to start the app:

UIApplicationMain(
    CommandLine.argc,
    CommandLine.unsafeArgv,
    nil,
    NSStringFromClass(appDelegateClass)
)

But this technique doesn't work for apps that use Scene Delegates to launch because scenes are cached between launches.

I can't imagine why you'd want more than one app delegate for tests. If it's to configure different settings at launch, I'd specify these settings at the Scheme level in the Test section, Arguments tab, "Arguments Passed at Launch". TestingAppDelegate can then read those arguments from UserDefaults.