Does anyone know a way to invoke a method that con...

# coroutines

[voghdev]

Does anyone know a way to invoke a method that contains a coroutine from a Unit Test?
for example calling this initialize() here from a test: https://github.com/voghDev/HelloKotlin/blob/coroutines/app/src/main/java/es/voghdev/hellokotlin/UserDetailPresenter.kt
(found Tony Owen's workaround but I'd prefer another solution: https://medium.com/@tonyowen/android-kotlin-coroutines-unit-test-16e984ba35b4)

[elizarov]

https://github.com/Kotlin/kotlinx.coroutines/blob/master/coroutines-guide.md#bridging-blocking-and-non-blocking-worlds

[voghdev]

Thanks for the prompt response! Still getting the Method getMainLooper in android.os.Looper not mocked error. Will push my code in a sec

[voghdev]

The exact Test I'm running is this one: https://github.com/voghDev/HelloKotlin/blob/coroutines2/app/src/test/kotlin/es/voghdev/hellokotlin/UserDetailPresenterTest.kt
The curious thing is that the Test seems to pass if I add a little delay(30). I keep on investigating, thanks for the link

[elizarov]

1. Change your UserDetailPresenter.initialize from fun initialize() { launch(CommonPool) { … } } to fun initialize() = launch(CommonPool) { … }, e.g. make it return the corresponding Job (you’ll need to change its super-class, too)
2. Now in your test code do it like this:

fun myTestForSomething() = runBlocking<Unit> { // this line !!! 
   …
   presenter.initialize().join() // wait for intilize job to complete!
}

Now you should not need to introduce delay

[voghdev]

Thanks Roman! I've refactored it to use launch and runBlocking as you suggested. Tests seem to be passing without the delay(30); Just one more question about launch(UI). Is it necessary to use it if I want to notify results in UI thread? If I uncomment lines 39, 42 to call launch(UI), tests are not passing anymore https://github.com/voghDev/HelloKotlin/blob/coroutines3/app/src/main/java/es/voghdev/hellokotlin/UserDetailPresenter.kt

[elizarov]

Yes. You have to do it from UI context. You can either uncomment your launch(UI) or replace CommonPool with UI on line 35