I have a question the proper way to test Navigatio...

# compose-wear

[Jeremiah Jordan]

I have a question the proper way to test Navigation in compose-wear.
When I use the TestNavHostController, and I create a graph with createGraph and composable(Screen.MainMenu.route) set I get a casting error:

java.lang.ClassCastException: androidx.navigation.testing.TestNavigatorProvider$navigator$1 cannot be cast to androidx.wear.compose.navigation.WearNavigator
at androidx.wear.compose.navigation.NavGraphBuilderKt.composable(NavGraphBuilder.kt:55)
at androidx.wear.compose.navigation.NavGraphBuilderKt.composable$default(NavGraphBuilder.kt:36)

If I don't create a graph, I get a null-pointer error, since there's nowhere to navigate to.
All the examples I see online seem to be using R.navigation, but I think that's used when your app uses an XML navigation definition, and not jetpack compose...

[Ian Lake]

Yes, TestNavHostController is only relevant to Navigation XML based apps using Fragments where individual fragments had a dependency on NavController.

In the Compose world, as explained in the docs, individual screens should not have any reference to Navigation at all, but instead expose events: https://developer.android.com/guide/navigation/use-graph/navigate#events

[Ian Lake]

The Encapsulate your navigation code page goes into more details on how you might separate your navigation logic from your individual screen: https://developer.android.com/guide/navigation/design/encapsulate

[Ian Lake]

So you shouldn't need any NavController at all to preview or test an individual screen and for integration style tests, you'd use your actual NavHost and its NavController

[Jeremiah Jordan]

Ah, that makes a lot of sense. Thanks for taking the time to answer my newbie question 😄