I have some Android instrumentation tests and a dependency declared in a module. In most of our test...

# koin

[Peter Farlow]

I have some Android instrumentation tests and a dependency declared in a module. In most of our tests, we want the normal dependency. But in one test file, we want to inject a mock version of the dependency. What's the best way to inject a mock dependency and then make sure to replace it with the normal dependency after the tests in that file are complete?

[Matt Thompson]

Hey Peter (long time no see) 👋 - if you call loadKoinModules with a module that’s been instantiated with override = true that has a dependency with the same type, it should override any modules that have already been loaded

[Matt Thompson]

so you could set up a JUnit rule or something to load your override module before tests and unload it after

[arnaud.giuliani]

from koin-test you have also declareMock API

[arnaud.giuliani]

to override a current def wih a mocked one

[Matt Thompson]

ah yeah I think I never got in the habit of using declareMock because I set up something as I described above before you added the MockProviderRule which decoupled the library from mockito

[Peter Farlow]

And Hi @Matt Thompson! Great to hear from you again!

[Peter Farlow]

Because Android instrumentation tests call our application's onCreate, koin has already been started by the time our test file starts running tests. I've found it hard to load in a specific mocked dependency in a single test file and then replace it afterwards because I can't call startKoin again. Will declareMock help with this?

[Matt Thompson]

hm yeah I’m not sure there’s anything that will automatically remove the declaration for you - all I’m seeing from DeclareMock.kt is that it instantiates the mock via your mockprovider and adds it to your definitions. might have to stick with loadKoinModules and unloadKoinModules for tests that don’t start/stop koin

[Peter Farlow]

The real solution here is the Android team should fix the test orchestrator on Android 11 so I don't have to worry about unloading test Koin modules interfering with other instrumentation tests https://github.com/android/android-test/issues/743