使用 Hilt 和 WorkManager 进行仪器测试

Question

I have an app that uses WorkManager to upload data to a server. I have end to end instrumentation tests written for the app that exercise several features including using work manager to upload the data. The app is currently using Dagger2 and I'm trying to upgrade to use Hilt and running into some issues getting instrumentation tests running.

The documentation for using Hilt with WorkManager is straightforward and recommends adding this to your Application class to setup work manager:

@HiltAndroidApp
class ExampleApplication : Application(), Configuration.Provider {

  @Inject lateinit var workerFactory: HiltWorkerFactory

  override fun getWorkManagerConfiguration() =
      Configuration.Builder()
            .setWorkerFactory(workerFactory)
            .build()
}

That works and I can run my app and use the features that use WorkManager. But now I need to run instrumentation tests and Hilt recommends using the provided HiltTestApplication as the Application class when running the instrumentation tests. This doesn't work for my app, because my app requires work manager to be fully functional, which requires my app's customized application class to exist. Hilt has a workaround for this problem and it allows you to provide your own test application class in the instrumentation tests.

@CustomTestApplication(BaseApplication::class)
class TestApplication : BaseApplication(), Application.ActivityLifecycleCallbacks {

  var currentActivity: FragmentActivity? = null

  override fun onCreate() {
    super.onCreate()
    registerActivityLifecycleCallbacks(this)
  }

  override fun onActivityPaused(p0: Activity) {}

  override fun onActivityResumed(activity: Activity) {
    if (activity is FragmentActivity) {
      currentActivity = activity
    }
  }

  override fun onActivityStarted(p0: Activity) {}

  override fun onActivityDestroyed(p0: Activity) {}

  override fun onActivitySaveInstanceState(p0: Activity, p1: Bundle) {}

  override fun onActivityStopped(p0: Activity) {}

  override fun onActivityCreated(p0: Activity, p1: Bundle?) {}
}

open class BaseApplication : Application() {

  @Inject lateinit var workerFactory: HiltWorkerFactory

  override fun onCreate() {
    super.onCreate()
    MapsInitializer.initialize(applicationContext, MapsInitializer.Renderer.LATEST, null)
    initUrlManager()
    RxJavaPlugins.setErrorHandler(emptyConsumer())
    WorkManager.initialize(
        this, Configuration.Builder().setWorkerFactory(workerFactory).build())
    }
}

And I use this custom test runner to specify the TestApplication class should be used in instrumentation tests:

class CustomTestRunner: AndroidJUnitRunner() {
    override fun newApplication(
        cl: ClassLoader,
        appName: String,
        context: Context
    ) : Application {
        return super.newApplication(
            cl, TestApplication::class.java.getName(), context)
    }
}

But when I try to run a test, I get the following error:

public final class TestApplication extends com.example.BaseApplication implements android.app.Application.ActivityLifecycleCallbacks { ^ @CustomTestApplication does not support application classes (or super classes) with @Inject fields. Found com.example.BaseApplication with @Inject fields [workerFactory]. [Hilt] Processing did not complete. See error above for details.

If I do what the error suggests and get rid of the @Inject field in my BaseApplication class, then I can't set the work manager factory when the app starts so that's not going to work.

Is there a known workaround for this situation? Is this issue I'm seeing due to some sort of architectural flaw where I just don't have my project setup correctly and could do away with initializing work manager in the application onCreate()?

Answer 1

You can use work-testing as mentioned in https://developer.android.com/topic/libraries/architecture/workmanager/how-to/integration-testing , then you have to inject workerFactory with HiltAndroidRule .

This worked for me:

@HiltAndroidTest
class MyInstrumentationTests() {

    @get:Rule
    private val hiltRule: HiltAndroidRule(this)
    
    @Inject
    lateinit var workerFactory: HiltWorkerFactory

    @Before
    fun setUp() {
        hiltRule.inject() // has to be called first to initialize workerFactory

        val context = InstrumentationRegistry.getInstrumentation().targetContext
        val config = Configuration.Builder()
            .setWorkerFactory(workerFactory)
            .setMinimumLoggingLevel(Log.DEBUG)
            .setExecutor(SynchronousExecutor())
            .build()

        // Initialize WorkManager for instrumentation tests.
        WorkManagerTestInitHelper.initializeTestWorkManager(context, config)
    }
}

With that setup there is no need for BaseApplication , just create a runner as advised in https://developer.android.com/training/dependency-injection/hilt-testing#test-application