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I currently have an app which uses a One Activity-Many Fragment approach, and within this app is a fragment which shares significant data with its children, and so I have used navGraphViewModels scoped to a nested nav graph as so:

private val viewModel by navGraphViewModels<MySharedViewModel>(R.id.nested_nav_graph)

The parent fragment contains a viewPager, and the fragments passed to that viewPager all share the same viewModel as the parent. My issue with using this approach is that when it comes to UI testing involving navGraphViewModels using Espresso, I was getting the error "View XXX does not have a NavController set." I managed to fix this for the parent fragment with the below:

        val navController = TestNavHostController(ApplicationProvider.getApplicationContext())
        // This allows fragments to use by navGraphViewModels()
        navController.setViewModelStore(ViewModelStore())
        UiThreadStatement.runOnUiThread {
            navController.setGraph(R.navigation.nested_nav_graph)
        }
        val scenario =
            launchFragmentInContainer(themeResId = R.style.AppTheme) {
                MyFragment().also { fragment ->
                    fragment.viewLifecycleOwnerLiveData.observeForever { viewLifecycleOwner ->
                        if (viewLifecycleOwner != null) {
                            Navigation.setViewNavController(fragment.requireView(), navController)
                        }
                    }
                }
            }
        return navController
    }

However, as the parent fragment then loads its child fragments into the viewPager and these also require a NavController, my tests don't proceed past the @Before block. Any help regarding how to set the navController to the child fragment would be appreciated.

Luke
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    this is a valid question, someone at google do something please! – BabyishTank Oct 12 '21 at 04:48
  • @Luke I am getting error as Error inflating class androidx.fragment.app.FragmentContainerView when I am using a FragmentContainerView inside a fragment (a fragment inside Nav graph). Due you have any idea how to solve that? – Nainal May 30 '22 at 11:49

0 Answers0