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Jetpack Compose instrument test with #HiltViewModel

So I want to test my jetpack compose project. It's easy enough running an instrument test following [these instructions]1 on android dev site, but when you add #HiltViewModel injection into the combination things get complicated.
I'm trying to test a pretty simple compose screen with a ViewModel that has an #Inject constructor.
The screen itself looks like this:
#Composable
fun LandingScreen() {
val loginViewModel: LoginViewModel = viewModel()
MyTheme {
Surface(color = MaterialTheme.colors.background) {
val user by loginViewModel.user.observeAsState()
if (user != null) {
MainScreen()
} else {
LoginScreen(loginViewModel)
}
}
}
}
and this is the view model:
#HiltViewModel
class LoginViewModel #Inject constructor(private val userService: UserService) : ViewModel() {
val user = userService.loggedInUser.asLiveData()
}
User service is of course backed by a room database and the loggedInUser property returns a Flow.
Things work as expected on standard run but when trying to run it in an instrument test it can't inject the view model.
#HiltAndroidTest
class LandingScreenTest {
#get:Rule
var hiltRule = HiltAndroidRule(this)
#get:Rule
val composeTestRule = createComposeRule()
#Inject
lateinit var loginViewModel: LoginViewModel
#Before
fun init() {
hiltRule.inject()
}
#Test
fun MyTest() {
composeTestRule.setContent {
MyTheme {
LandingScreen()
}
}
composeTestRule.onNodeWithText("Welcome").assertIsDisplayed()
}
}
Injection of an #HiltViewModel class is prohibited since it does not
create a ViewModel instance correctly. Access the ViewModel via the
Android APIs (e.g. ViewModelProvider) instead. Injected ViewModel:
com.example.viewmodels.LoginViewModel
How do you make that work with the ViewModelProvider instead of the #HiltViewModel?

Hilt needs an entry point to inject fields. In this case that would probably be an Activity annotated with #AndroidEntryPoint. You can use your MainActivity for that, but that would mean that you would then have to add code to every test to navigate to the desired screen which could be tedious depending on the size of your app, and is not feasible if your project is multimodule and your current Test file does not have access to MainActivity. Instead, you could create a separate dummy Activity whose sole purpose is to host your composable (in this case LoginScreen) and annotate it with #AndroidEntryPoint. Make sure to put it into a debug directory so it's not shipped with the project. Then you can use createAndroidComposeRule<Activity>() to reference that composable. You dont need to inject the ViewModel directly so get rid of that line too.
In the end your Test File should look like this:
#HiltAndroidTest
class LandingScreenTest {
#get:Rule(order = 0)
val hiltRule = HiltAndroidRule(this)
#get:Rule(order = 1)
val composeRule = createAndroidComposeRule<LoginTestActivity>()
#Before
fun init() {
hiltRule.inject()
}
#Test
fun MyTest() {
composeTestRule.onNodeWithText("Welcome").assertIsDisplayed()
}
}
And your your dummy activity can look like this:
#AndroidEntryPoint
class LoginTestActivity : ComponentActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContent {
LoginScreen()
}
}
}
And the debug directory would look like this:debug directory with dummy activity
Yes the debug directory has its own manifest and that is where you should add the dummy activity. set exported to false.

Try to do something like this:
#HiltAndroidTest
class LandingScreenTest {
#get:Rule
var hiltRule = HiltAndroidRule(this)
#get:Rule
val composeTestRule = createComposeRule()
// Remove this line #Inject
lateinit var loginViewModel: LoginViewModel
#Before
fun init() {
hiltRule.inject()
}
#Test
fun MyTest() {
composeTestRule.setContent {
loginViewModel= hiltViewModel() // Add this line
MyTheme {
LandingScreen()
}
}
composeTestRule.onNodeWithText("Welcome").assertIsDisplayed()
}
}

You must annotate any UI test that uses Hilt with #HiltAndroidTest. This annotation is responsible for generating the Hilt components for each test.
https://developer.android.com/training/dependency-injection/hilt-testing

Android test Fragmen with mock ViewModel using Hilt

I´m developing an app using Hilt, all works fine but when I try to run some Espresso test on a device running on below Android P I have encountered an issue.
The problem comes when I try to mock (using Mockk) the ViewModel so I can unit test my Fragment. When the Fragment will try to instanciate te ViewModel I got a NullPointerException when the ViewModel is being created. The NPE is thrown on the method setTagIfAbsent. The problem is that this method is package private as you can see on ViewModel source code, so it can not be mocked on Android < P.
I have tried by using the Kotlin All-Open plugin, it has helped on mocking the ViewModel and stubing it public methods. I try to stub the setTagIfAbsent by using the mockk private stubbing, like this:
every{
myViewModelMock["setTagIfAbsent"](any<String>,any())
} answers {secondArg()}
But when setTagIfAbsent is called, the real method is invoked, throwing the NPE because the ViewModel.mBagOfTags is null because the class is a mock.
The rest of the code is the following:
ViewModel:
#OpenForTesting
#HiltViewModel
class MyViewModel #Inject constructor MyViewModel(private val dependency: Dependency): ViewModel(){
//Rest of the code
}
Fragment:
#AndroidEntryPoint
class MyFragment: Fragment(){
private val viewModel: MyViewModel by viewModels()
//Rest of the code
}
Test class:
#HiltAndroidTest
#RunWith(AndroidJUnit4::class)
class MyFragmentTest {
#Bind
#MockK
lateinit var viewModel: MyViewModel
#get:Rule
var hiltRule = HiltAndroidRule(this)
#Before
fun prepareTest(){
MockkAnnotations.init(this)
hiltRule.inject()
launchFragmentInHiltContainer<MyFragment>()
}
#Test
fun testThatWillMakeAViewModelInvokation(){
onView(withId(R.id.button)).perform(click())
//Assume that button will make the ViewModel be called and created by the delegate
//When this happens the NPE is thrown
}
}
The method launchFragmentInHiltContainer comes from here (Hilt sample app).
If you look at the Mockk Android documentation it is said that < Android P the private methods can not be mocked (it is also said for finals, but the OpenClass plugin fix that problem).
Does anyone have an idea of how can I workaround this or how to fix the test?
Thanks in advance.

Instead of mocking setTagIfAbsent you can mock mBagOfTags using reflection on already mocked instance of ViewModel.
setInternalFieldValue(mockedViewModel, "mBagOfTags", HashMap<String, Any>())
fun setInternalFieldValue(target: Any, fieldName: String, value: Any, javaClass: Class<in Any> = target.javaClass) {
try {
val field = javaClass.getDeclaredField(fieldName)
field.isAccessible = true
field.set(target, value)
} catch (exception: NoSuchFieldException) {
val superClass = javaClass.superclass
if (superClass != null) {
setInternalFieldValue(target, fieldName, value, superClass)
} else {
throw RuntimeException("Field $fieldName is not declared in a hierarchy of this class")
}
}
}

If you use mockk(relaxed = true) this problem is solved

Android Test Koin NoBeanDefFoundException

I'm trying to do some Android Tests with Koin and so far, it is not a success.
I want to test a basic Activity with a ViewModel, injected by Koin.
I already read posts like NoBeanDefFoundException with Mock ViewModel, testing with Koin, Espresso but so far I still have the error.
Here is the code relative to the tests configuration
A specific app that start with no module.
class MyTestApplication : Application() {
override fun onCreate() {
super.onCreate()
startKoin { emptyList<Module>() }
}
}
A specific runner that uses the test app
class OccazioTestRunner : AndroidJUnitRunner() {
override fun newApplication(
cl: ClassLoader?,
className: String?,
context: Context?
): Application {
return super.newApplication(cl, MyTestApplication::class.java.name, context)
}
}
That is defined in my app build.gradle to be used as runner
android {
defaultConfig {
testInstrumentationRunner "fr.dsquad.occazio.occazio.OccazioTestRunner"
}
}
And now the code I want to test
In my MyActivity
class MyActivity : AppCompatActivity(R.layout.activity_my) {
private val myViewModel by viewModel<MyViewModel>()
// Some code
}
And the viewmodel
class MyViewModel(private val useCase: MyUseCase): ViewModel() {
// Some code
}
And finally, the test itself (in androidTest)
#LargeTest
class MyActivityTest : KoinTest {
private lateinit var mockUseCase: MyUseCase
#JvmField
#Rule
val activityRule = activityScenarioRule<MyActivity>()
#Before
fun setup() {
mockUseCase = mock(MyUseCase::class.java)
startKoin {
modules(module { viewModel { MyViewModel(mockUseCase) } })
}
// I've also tried this
loadKoinModules(
module { viewModel { MyViewModel(mockUseCase) } }
)
}
#After
fun cleanUp() {
stopKoin()
}
#Test
fun someTest() = runBlocking {
// Mock the usecase response
`when`(mockUseCase.doSomething()).thenReturn("taratata")
// Start the scenario
val scenario = activityRule.scenario
// Verify we call the getUserId
// Activity is supposed to call the view model that will call the method doSomethingAdterThat.
verify(mockUseCase, times(1)).doSomethingAfterThat()
return#runBlocking
}
}
And so far, everytime I run this code I have this error
org.koin.core.error.NoBeanDefFoundException:
No definition found for 'mypackage.MyViewModel' has been found. Check your module definitions.
What is interesting is that, when
I change the rule activityScenarioRule by the old deprecated ActivityTestRule(SplashScreenActivity::class.java, true, false)
I change val scenario = activityRule.scenario by val scenario = activityRule.launchActivity(null)
I use loadKoinModules and not startKoin in setUp
Two things happen
When my test is started alone (via Android Studio): it passes.
When my test is started with other tests (by the class or with connectedAndroidTest), only one of them passes and old the others are KO.
So I have two questions in fact here.
How can I make this test work with activityScenarioRule ?
How can I make them "all" work (and not start them one by one to make them work) ?

Ok, don't ask me how it works but I figured it out.
First of all, as I needed config I followed this https://medium.com/stepstone-tech/better-tests-with-androidxs-activityscenario-in-kotlin-part-1-6a6376b713ea .
I've done 3 things
First, I needed to configure koin before startup, to do that, I needed to use ActivityScenario.launch() with an intent that I defined earlier
private val intent = Intent(ApplicationProvider.getApplicationContext(), MyActivity::class.java)
var activityRule : ActivityScenario<MyActivity>? = null
// And then I can start my activity calling
activityRule = ActivityScenario.launch(intent)
Then "KoinApp was not started"... I just replaced the loadKoinModules block with the startKoin one in setUp
startKoin { modules(module { viewModel { MyViewModel(mockUseCase) } }) }
Finally, it worked for 1 test, but the others were failing because "KoinAppAlreadyStartedException" like the stopKoin() was not called. So I found out that I should extend AutoCloseKoinTest instead of KoinTest.. But no success.
In the end, I've put a stopKoin() before the startKoin and now, everything works like a charm.
Here is my complete code that works
#LargeTest
class MyActivityTest : KoinTest() {
private val intent = Intent(ApplicationProvider.getApplicationContext(), MyActivity::class.java)
var activityRule : ActivityScenario<MyActivity>? = null
private lateinit var mockUseCase: MyUseCase
#Before
fun setup() {
mockUseCase = mock(MyUseCase::class.java)
stopKoin()
startKoin {
modules(module { viewModel { MyViewModel(mockUseCase) } })
}
}
#After
fun cleanUp() {
activityRule?.close()
}
#Test
fun someTest() = runBlocking {
// Mock the usecase response
`when`(mockUseCase.doSomething()).thenReturn("taratata")
// Start the rule
val activityRule = ActivityScenario.launch(intent)
// Verify we call the getUserId
// Activity is supposed to call the view model that will call the method doSomethingAdterThat.
verify(mockUseCase, times(1)).doSomethingAfterThat()
return#runBlocking
}
}
Ho, I've also added this code to my two Applications
override fun onTerminate() {
super.onTerminate()
stopKoin()
}
Just to be sure !

Testing Navigation component: "does not have a NavController"

I'm implementing Espresso tests. I'm using a Fragment with a NavGraph scoped ViewModel. The problem is when I try to test the Fragment I got an IllegalStateException because the Fragment does not have a NavController set. How can I fix this problem?
class MyFragment : Fragment(), Injectable {
private val viewModel by navGraphViewModels<MyViewModel>(R.id.scoped_graph){
viewModelFactory
}
#Inject
lateinit var viewModelFactory: ViewModelProvider.Factory
//Other stuff
}
Test class:
class FragmentTest {
class TestMyFragment: MyFragment(){
val navMock = mock<NavController>()
override fun getNavController(): NavController {
return navMock
}
}
#Mock
private lateinit var viewModel: MyViewModel
private lateinit var scenario: FragmentScenario<TestMyFragment>
#Before
fun prepareTest(){
MockitoAnnotations.initMocks(this)
scenario = launchFragmentInContainer<TestMyFragment>(themeResId = R.style.Theme_AppCompat){
TestMyFragment().apply {
viewModelFactory = ViewModelUtil.createFor(viewModel)
}
}
// My test
}
Exception I got:
java.lang.IllegalStateException: View android.widget.ScrollView does not have a NavController setjava.lang.IllegalStateException

As can be seen in docs, here's the suggested approach:
// Create a mock NavController
val mockNavController = mock(NavController::class.java)
scenario = launchFragmentInContainer<TestMyFragment>(themeResId = R.style.Theme_AppCompat) {
TestMyFragment().also { fragment ->
// In addition to returning a new instance of our Fragment,
// get a callback whenever the fragment’s view is created
// or destroyed so that we can set the mock NavController
fragment.viewLifecycleOwnerLiveData.observeForever { viewLifecycleOwner ->
if (viewLifecycleOwner != null) {
// The fragment’s view has just been created
Navigation.setViewNavController(fragment.requireView(), mockNavController)
}
}
}
}
Thereafter you can perform verification on mocked mockNavController as such:
verify(mockNavController).navigate(SearchFragmentDirections.showRepo("foo", "bar"))
See architecture components sample for reference.
There exists another approach which is mentioned in docs as well:
// Create a graphical FragmentScenario for the TitleScreen
val titleScenario = launchFragmentInContainer<TitleScreen>()
// Set the NavController property on the fragment
titleScenario.onFragment { fragment ->
Navigation.setViewNavController(fragment.requireView(), mockNavController)
}
This approach won't work in case there happens an interaction with NavController up until onViewCreated() (included). Using this approach onFragment() would set mock NavController too late in the lifecycle, causing the findNavController() call to fail. As a unified approach which will work for all cases I'd suggest using first approach.

You are missing setting the NavController:
testFragmentScenario.onFragment {
Navigation.setViewNavController(it.requireView(), mockNavController)
}

How to correctly mock ViewModel on androidTest

I'm currently writing some UI unit tests for a fragment, and one of these #Test is to see if a list of objects is correctly displayed, this is not an integration test, therefore I wish to mock the ViewModel.
The fragment's vars:
class FavoritesFragment : Fragment() {
private lateinit var adapter: FavoritesAdapter
private lateinit var viewModel: FavoritesViewModel
#Inject lateinit var viewModelFactory: FavoritesViewModelFactory
(...)
Here's the code:
#MediumTest
#RunWith(AndroidJUnit4::class)
class FavoritesFragmentTest {
#Rule #JvmField val activityRule = ActivityTestRule(TestFragmentActivity::class.java, true, true)
#Rule #JvmField val instantTaskExecutorRule = InstantTaskExecutorRule()
private val results = MutableLiveData<Resource<List<FavoriteView>>>()
private val viewModel = mock(FavoritesViewModel::class.java)
private lateinit var favoritesFragment: FavoritesFragment
#Before
fun setup() {
favoritesFragment = FavoritesFragment.newInstance()
activityRule.activity.addFragment(favoritesFragment)
`when`(viewModel.getFavourites()).thenReturn(results)
}
(...)
// This is the initial part of the test where I intend to push to the view
#Test
fun whenDataComesInItIsCorrectlyDisplayedOnTheList() {
val resultsList = TestFactoryFavoriteView.generateFavoriteViewList()
results.postValue(Resource.success(resultsList))
(...)
}
I was able to mock the ViewModel but of course, that's not the same ViewModel created inside the Fragment.
So my question really, has someone done this successfully or has some pointers/references that might help me out?
Also, I've tried looking into the google-samples but with no luck.
For reference, the project can be found here: https://github.com/JoaquimLey/transport-eta/

Within your test setup you'll need to provide a test version of the FavoritesViewModelFactory which is being injected in the Fragment.
You could do something like the following, where the Module will need to be added to your TestAppComponent:
#Module
object TestFavoritesViewModelModule {
val viewModelFactory: FavoritesViewModelFactory = mock()
#JvmStatic
#Provides
fun provideFavoritesViewModelFactory(): FavoritesViewModelFactory {
return viewModelFactory
}
}
You'd then be able to provide your Mock viewModel in the test.
fun setupViewModelFactory() {
whenever(TestFavoritesViewModelModule.viewModelFactory.create(FavoritesViewModel::class.java)).thenReturn(viewModel)
}

I have solved this problem using an extra object injected by Dagger, you can find the full example here: https://github.com/fabioCollini/ArchitectureComponentsDemo
In the fragment I am not using directly the ViewModelFactory, I have defined a custom factory defined as a Dagger singleton:
https://github.com/fabioCollini/ArchitectureComponentsDemo/blob/master/uisearch/src/main/java/it/codingjam/github/ui/search/SearchFragment.kt
Then in the test I replace using DaggerMock this custom factory using a factory that always returns a mock instead of the real viewModel:
https://github.com/fabioCollini/ArchitectureComponentsDemo/blob/master/uisearchTest/src/androidTest/java/it/codingjam/github/ui/repo/SearchFragmentTest.kt

Look like, you use kotlin and koin(1.0-beta).
It is my decision for mocking
#RunWith(AndroidJUnit4::class)
class DashboardFragmentTest : KoinTest {
#Rule
#JvmField
val activityRule = ActivityTestRule(SingleFragmentActivity::class.java, true, true)
#Rule
#JvmField
val executorRule = TaskExecutorWithIdlingResourceRule()
#Rule
#JvmField
val countingAppExecutors = CountingAppExecutorsRule()
private val testFragment = DashboardFragment()
private lateinit var dashboardViewModel: DashboardViewModel
private lateinit var router: Router
private val devicesSuccess = MutableLiveData<List<Device>>()
private val devicesFailure = MutableLiveData<String>()
#Before
fun setUp() {
dashboardViewModel = Mockito.mock(DashboardViewModel::class.java)
Mockito.`when`(dashboardViewModel.devicesSuccess).thenReturn(devicesSuccess)
Mockito.`when`(dashboardViewModel.devicesFailure).thenReturn(devicesFailure)
Mockito.`when`(dashboardViewModel.getDevices()).thenAnswer { _ -> Any() }
router = Mockito.mock(Router::class.java)
Mockito.`when`(router.loginActivity(activityRule.activity)).thenAnswer { _ -> Any() }
StandAloneContext.loadKoinModules(hsApp + hsViewModel + api + listOf(module {
single(override = true) { router }
factory(override = true) { dashboardViewModel } bind ViewModel::class
}))
activityRule.activity.setFragment(testFragment)
EspressoTestUtil.disableProgressBarAnimations(activityRule)
}
#After
fun tearDown() {
activityRule.finishActivity()
StandAloneContext.closeKoin()
}
#Test
fun devicesSuccess(){
val list = listOf(Device(deviceName = "name1Item"), Device(deviceName = "name2"), Device(deviceName = "name3"))
devicesSuccess.postValue(list)
onView(withId(R.id.rv_devices)).check(ViewAssertions.matches(ViewMatchers.isCompletelyDisplayed()))
onView(withId(R.id.rv_devices)).check(matches(hasDescendant(withText("name1Item"))))
onView(withId(R.id.rv_devices)).check(matches(hasDescendant(withText("name2"))))
onView(withId(R.id.rv_devices)).check(matches(hasDescendant(withText("name3"))))
}
#Test
fun devicesFailure(){
devicesFailure.postValue("error")
onView(withId(R.id.rv_devices)).check(ViewAssertions.matches(ViewMatchers.isCompletelyDisplayed()))
Mockito.verify(router, times(1)).loginActivity(testFragment.activity!!)
}
#Test
fun devicesCall() {
onView(withId(R.id.rv_devices)).check(ViewAssertions.matches(ViewMatchers.isCompletelyDisplayed()))
Mockito.verify(dashboardViewModel, Mockito.times(1)).getDevices()
}
}

In the example you provided, you are using mockito to return a mock for a specific instance of your view model, and not for every instance.
In order to make this work, you will have to have your fragment use the exact view model mock that you have created.
Most likely this would come from a store or a repository, so you could put your mock there? It really depends on how you setup the acquisition of the view model in your Fragments logic.
Recommendations:
1) Mock the data sources the view model is constructed from or
2) add a fragment.setViewModel() and Mark it as only for use in tests. This is a little ugly, but if you don't want to mock data sources, it is pretty easy this way.

One could easily mock a ViewModel and other objects without Dagger simply by:
Create a wrapper class that can re-route calls to the ViewModelProvider. Below is the production version of the wrapper class that simply passes the calls to the real ViewModelProvider which is passed in as a parameter.
class VMProviderInterceptorImpl : VMProviderInterceptor { override fun get(viewModelProvider: ViewModelProvider, x: Class<out ViewModel>): ViewModel {
return viewModelProvider.get(x)
}
}
Adding getters and setters for this wrapper object to the Application class.
In the Activity rule, before an activity is launched, swap out the real wrapper with a mocked wrapper that does not route the get ViewModel call to the real viewModelProvider and instead provides a mocked object.
I realize this is not as powerful as dagger but the simplicity is attractive.