android - 如何使用条件导航将 androidTest 添加到 fragment ？

Question

我正在尝试添加 test navigation conditional navigation 文档中的示例.

我按照示例创建了一个演示并将其发布在 github 上.

演示包含 3 个 fragment :HomeFragment , ProfileFragment和 LoginFragment .在ProfileFragment有条件检查用户是否已连接。如果用户未连接，他将被发送到 LoginFragment .

个人资料 fragment

@AndroidEntryPoint
class ProfileFragment : Fragment(R.layout.fragment_profile) {
    private val mainViewModel: MainViewModel by activityViewModels()
    private val navController by lazy { findNavController() }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        val currentBackStackEntry = navController.currentBackStackEntry!!
        currentBackStackEntry.savedStateHandle.getLiveData<Boolean>(LoginFragment.LOGIN_SUCCESSFUL)
            .observe(currentBackStackEntry, { success ->
                if (!success) {
                    val startDestination = navController.graph.startDestination
                    val navOptions = NavOptions.Builder()
                        .setPopUpTo(startDestination, true)
                        .build()
                    navController.navigate(startDestination, null, navOptions)
                }
            })
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        mainViewModel.user.observe(viewLifecycleOwner, {
            if(!it){
                navController.navigate(R.id.loginFragment)
            }
        })
    }
}

如文档中所述，在 onCreate() 中方法我正在观察 LOGIN_SUCCESSFUL值存储在 SavedStateHandle 中以便在用户未登录时重定向用户。

登录 fragment

@AndroidEntryPoint
class LoginFragment : Fragment() {
    companion object {
        const val LOGIN_SUCCESSFUL: String = "LOGIN_SUCCESSFUL"
    }

    private val viewModel: LoginViewModel by viewModels()
    private val navController by lazy { findNavController() }

    private lateinit var savedStateHandle: SavedStateHandle
    private lateinit var binding: FragmentLoginBinding

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        binding = DataBindingUtil.inflate(inflater, R.layout.fragment_login, container, false)
        binding.viewModel = viewModel
        binding.lifecycleOwner = this
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        savedStateHandle = navController.previousBackStackEntry!!.savedStateHandle
        savedStateHandle.set(LOGIN_SUCCESSFUL, false)

        viewModel.login.observe(viewLifecycleOwner, ResultObserver {
            if (it.status == Status.ERROR) {
                Snackbar.make(requireView(), it.message ?: "Error", Snackbar.LENGTH_SHORT).show()
            } else if (it.status == Status.SUCCESS) {
                savedStateHandle.set(LOGIN_SUCCESSFUL, true)
                navController.popBackStack()
            }
        })
    }
}

测试

@Test
fun profileFragment_unauthenticated() {
    setAuthentication(false)

    val navController = TestNavHostController(ApplicationProvider.getApplicationContext())

    launchFragmentInHiltContainer<ProfileFragment> {
        navController.setViewModelStore(ViewModelStore())
        navController.setGraph(R.navigation.nav_main)
        navController.setCurrentDestination(R.id.profileFragment)
        Navigation.setViewNavController(requireView(), navController)
    }
    assertEquals(navController.currentDestination?.id, R.id.loginFragment)
}

因为我使用 Hilt 进行依赖项注入(inject)，所以我需要将 fragment 附加到用 @AndroidEntryPoint 注释的 Activity 中: launchFragmentInHiltContainer

在测试期间，我正在创建 TestNavHostController 的实例并将其分配给 fragment 。

问题是我正在访问 navController在onCreate navController 的方法在 RESUMED 期间实例化状态(参见 FragmentScenario)。导致 java.lang.IllegalStateException: Fragment ProfileFragment ... does not have a NavController set

我知道可以制作 navController通过向 fragment 的 viewLifecycleOwnerLiveData 添加观察者可以更快地使用.然而，这还不够快。

那么，这种情况下如何实现测试导航呢？

可能的解决方案

在寻找向我的 fragment 添加测试的方法几天后，我认为我找到了解决方案。这个想法是附上 navController到 Activity 。但是，我对结果并不完全满意，这就是为什么我没有将此解决方案作为答案发布的原因。对于任何感兴趣的人，我将我的解决方案添加到 github repository .

Answer 1

I know it's possible to make the navController available sooner by adding an observer to the fragment's viewLifecycleOwnerLiveData. However, it is not soon enough.

其实你用错了。

正如这里提到的谷歌文档 https://developer.android.com/guide/navigation/navigation-testing#test_navigationui_with_fragmentscenario

他们使用具有 FragmentFactory 的 launchFragmentInContainer 来控制 Fragment 的实例化实例。

这就是您使用 activity.supportFragmentManager.fragmentFactory 创建 fragment 的方式

   val fragment: Fragment = activity.supportFragmentManager.fragmentFactory.instantiate(
        Preconditions.checkNotNull(T::class.java.classLoader),
        T::class.java.name
    )

将 activity.supportFragmentManager.fragmentFactory 替换为

 val fragmentFactory = object : FragmentFactory() {
        override fun instantiate(
            classLoader: ClassLoader,
            className: String
        ) = when (className) {
            T::class.java.name -> action()
            else -> super.instantiate(classLoader, className)
        }
    }

所以你会像这样创建 fragment

 val fragment: Fragment = fragmentFactory.instantiate(
        Preconditions.checkNotNull(T::class.java.classLoader),
        T::class.java.name
    )

替换 crossinline Action :Activity.() -> Unit = {}

使用 crossinline Action :() -> T

删除 activity.action() 因为它已经在 FragmentFactory 中使用了，正如您在上面看到的那样

所以

launchFragmentInHiltContainer()

看起来像这样

inline fun <reified T : Fragment> launchFragmentInHiltContainer(
fragmentArgs: Bundle? = null,
@StyleRes themeResId: Int = R.style.FragmentScenarioEmptyFragmentActivityTheme,
crossinline action: () -> T) {
val startActivityIntent = Intent.makeMainActivity(
    ComponentName(
        ApplicationProvider.getApplicationContext(),
        HiltTestActivity::class.java
    )
).putExtra(
    "androidx.fragment.app.testing.FragmentScenario.EmptyFragmentActivity.THEME_EXTRAS_BUNDLE_KEY",
    themeResId
)

ActivityScenario.launch<HiltTestActivity>(startActivityIntent).onActivity { activity ->

    val fragmentFactory = object : FragmentFactory() {
        override fun instantiate(
            classLoader: ClassLoader,
            className: String
        ) = when (className) {
            T::class.java.name -> action()
            else -> super.instantiate(classLoader, className)
        }
    }

    val fragment: Fragment = fragmentFactory.instantiate(
        Preconditions.checkNotNull(T::class.java.classLoader),
        T::class.java.name
    )

    fragment.arguments = fragmentArgs
    activity.supportFragmentManager
        .beginTransaction()
        .add(android.R.id.content, fragment, "")
        .commitNow()
} }

现在您可以使用 google here 提供的相同代码和 hilt 注入(inject)，如下所示

       launchFragmentInHiltContainer {
       ProfileFragment().also { fragment ->
            fragment.viewLifecycleOwnerLiveData.observeForever { viewLifecycleOwner ->
                if (viewLifecycleOwner != null) {
                    navController.setViewModelStore(ViewModelStore())
                    navController.setGraph(R.navigation.nav_main)
                    navController.setCurrentDestination(R.id.profileFragment)
                    Navigation.setViewNavController(requireView(), navController)
                }
            }
        }
    }