How do I test the fails of a test that relies on a

suspend

funciton? Let's consider this class

/**
 * Allows the login of a user based on his private key.
 */
class PerformLoginUseCase internal constructor(private val repository: AuthenticationRepository){

    /**
     * Logs the user into the system using the given [authKey].
     * @return the user data once the login has been successful.
     */
    suspend operator fun invoke(authKey: PrivateKey): UserData {
        return repository.login(authKey)
    }
}

I have the following test

@Test
fun useCaseThrowsExceptionWhenRepositoryDoes() {
    assertFailsWith(Throwable::class) {
        coEvery { repository.login(any()) } throws Throwable()
        GlobalScope.launch { performLogin(mockk()) }
    }
}

While this should work properly, it fails with an

assertionError

. I think the exception is not raised in time, so who should I do this?

Because you run background job that return immediately and there is no chance for assertFailsWith catch it It’s like this code, there is no way to catch exception in this case too

assertFailsWith(Throwable::class) {
   thread { error("Some error") }
}

It's a common test, and I can't use the

runBlocking

method inside. I don't know why, but wit hthe following dependencies, it is not included:

implementation deps.kotlin.stdlib.common
implementation deps.kotlinx.coroutines.common
implementation deps.kotlin.test.common
implementation deps.kotlin.test.annotations
implementation deps.kotlinx.coroutines.test

runBlocking is not available in MPP

Thank you very much. Any ETA on Kotlin 1.3.30?

as usual, will be available when will be ready %)

Thank you very much!

but anyway, you can workaround it with expect/actual + dynamic type for JS