Inject provider of ViewModelProvider.Factory into esspresso test

Issue

I have custom implementation of ViewModel.Factory which is provided by lambda injected by Dagger2

interface ViewModelFactoryComponent {
    val factoryProvider: (Bundle?) -> ViewModelProvider.Factory
}

Dagger implementation looks like below:

@Module
class ViewModelModule {
    @Provides
    @Singleton
    fun bindViewModelFactory(creators: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<(Bundle?) -> ViewModel>>): (Bundle?) -> ViewModelProvider.Factory {
        return { ViewModelFactory(creators, it) }
    }
}

@Singleton
@Component(modules = [ ApplicationModule::class, ViewModelModule::class])
interface ApplicationComponent : ViewModelFactoryComponent

In application everything works like a charm but problem appeared when I've tried to configure Espresso test. Here's dagger test component configuration:

@Singleton
@Component(modules = [ApplicationModule::class, ViewModelModule::class])
interface TestComponent : ApplicationComponent

Now what is the problem - test component implementation generated by dagger generate function like this

 @Override
  public Function1<Bundle, ViewModelProvider$Factory> getFactoryProvider() {
    return bindViewModelFactoryProvider.get();
  }

which generate compilation error, instead like in real app:

  @Override
  public Function1<Bundle, ViewModelProvider.Factory> getFactoryProvider() {
    return bindViewModelFactoryProvider.get();
  }

First I thought it's a case of ViewModelProvider.Factory visibility, but all build.gradle modification didn't help. I've met with total lack of idea so I will be greatfull for at least some suggestions.

UPDATE I have created empty project to reproduce this error and it suppose to be completly repeatable.

File in main directory:

@Singleton
@Component(modules = [ViewModelModule::class])
interface ApplicationComponent : ViewModelFactoryComponent

@Module
class ViewModelModule {

    @Provides
    @Singleton
    fun bindViewModelFactory(): () -> ViewModelProvider.Factory {
        return { ViewModelFactory() }
    }
}

interface ViewModelFactoryComponent {
    val factoryProvider: () -> ViewModelProvider.Factory
}

class ViewModelFactory @Inject constructor() : ViewModelProvider.Factory {
    override fun <T : ViewModel> create(modelClass: Class<T>): T {
        return modelClass.newInstance()
    }
}

class MainActivity : AppCompatActivity()

File in androidTest directory:

@Singleton
@Component(modules = [ViewModelModule::class])
interface TestComponent : ApplicationComponent

@RunWith(AndroidJUnit4::class)
class TestCase {
    @get:Rule
    val activityTestRule = ActivityTestRule(MainActivity::class.java, false, false)

    @Test
    fun appLaunchesSuccessfully() {
        ActivityScenario.launch(MainActivity::class.java)
    }
}

And this are all dependencies:

    implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'androidx.appcompat:appcompat:1.0.2'
    implementation 'com.google.dagger:dagger:2.21'
    kapt 'com.google.dagger:dagger-compiler:2.21'
    kaptAndroidTest 'com.google.dagger:dagger-compiler:2.21'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
    androidTestImplementation 'androidx.test.ext:junit:1.1.0'
    androidTestImplementation 'androidx.test:rules:1.1.1'

Application is build without any problem but when I try to launch appLaunchesSuccessfully() test, compile error from reason above, appear.

Edit So, I figured out that without kaptAndroidTest 'com.google.dagger:dagger-compiler:2.21' test project can be build successfully.
The bad new is that without it dagger component class won't generate.

Solution

According to https://github.com/google/dagger/issues/1454 and https://youtrack.jetbrains.net/issue/KT-27936 there is only a temporary solution under first link

Answered By - Karol Kulbaka