I am running into an issue when running the UI test for a compose component. The error is "Cannot create an instance of class ........ViewModel". The component is like this

@Composable
fun ExampleView(
    navController: NavController,
    testViewModel: TestViewModel = hiltViewModel()
) {}

Here is how I am calling from the test of this component.

class ExampleViewTest {

    @get:Rule
    val composeTestRule = createComposeRule()

    @Test
    fun test_exampleView() {
        val navController = TestNavHostController(
            ApplicationProvider.getApplicationContext()
        )

        composeTestRule.setContent {
            ExampleView(navController = navController)
        }
    }
}

Here is the TestViewModel set up

@HiltViewModel
class TestViewModel @Inject constructor(
    private val testRepo: TestRepo
) : ViewModel() {
}

Just pass in the view model as you pass the nav controller. So do „manual“ dependency injection. That’s why you define it as a default parameter - so you can „override“ it in your test. Hilt will not work in a unit test. I think there is something like a hilt rule where you can build a test dependency tree but I’ve never used .

can you please explain more? I am really new to jetpack compose as well as it's UI testing.

I think that’s out of the context for this workspace. Your lack in knowledge is not testing but dependency injection in general. I think I gave you enough hints to look for Medium articles. Also have a look at all the google compose sample apps. They all have test and do manual dependency injection in there.

Seen your follow up in the chat. Christian is spot on in what he's suggesting, essentially you need to create an instance of your ViewModel in your test (or perhaps a mock/dummy/fake instance) and pass that through to your view, not using the default value 🙂