基于Dagger Hilt的单元测试

深碍√TFBOYSˉ_ 2023-01-01 07:57 196阅读 0赞

# architecture-samples #

--------------------

`android/architecture-samples`是google官方的sample项目：TODO-APP，通过其可以学习androidx中各种组件的使用。其中`dev-hilt`分支展示了Dagger Hilt的使用：  
[https://github.com/android/architecture-samples/tree/dev-hilt][https_github.com_android_architecture-samples_tree_dev-hilt]（hash：f2fd9ce969a431b20218f3ace38bbb95fd4d1151），  
除了Hilt的使用，还可以了解一下如何使用Hilt进行单元测试。

一个Hilt项目通常会涉及以下Component，本文介绍几个最主要的Component以及其单元测试的方法  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3ZpdGF2aXZh_size_16_color_FFFFFF_t_70]  
图片引自[https://developer.android.com/training/dependency-injection/hilt-android][https_developer.android.com_training_dependency-injection_hilt-android]

# ApplicationComponent #

--------------------

为Application添加`@HiltAndroidApp`注解，将其关联到`ApplicationComponent`

@HiltAndroidApp
    class TodoApplication : Application() { 
    
        override fun onCreate() { 
            super.onCreate()
            if (BuildConfig.DEBUG) Timber.plant(DebugTree())
        }
    }

通过`@InstallIn`，将AppModule和TasksRepositoryModule安装到ApplicationComponent

ApplicationComponent

*  AppModule
 *  TasksRepositoryModule

@Module
    @InstallIn(ApplicationComponent::class)
    object AppModule { 
    ...
    }
    
    /** * The binding for TasksRepository is on its own module so that we can replace it easily in tests. */
    @Module
    @InstallIn(ApplicationComponent::class)
    object TasksRepositoryModule { 
    ...
    }

AppModule用来提供多种`TasksDataSource`，例如LocalTasksDataSource、LocalTasksDataSourced等。  
使用`@Qualifier`元注解用来区分不同的DataSource类型。

@Module
    @InstallIn(ApplicationComponent::class)
    object AppModule { 
    
        @Qualifier
        @Retention(RUNTIME)
        annotation class RemoteTasksDataSource
    
        @Qualifier
        @Retention(RUNTIME)
        annotation class LocalTasksDataSource
    ...
    
        @Singleton
        @LocalTasksDataSource
        @Provides
        fun provideTasksLocalDataSource(
            database: ToDoDatabase,
            ioDispatcher: CoroutineDispatcher
        ): TasksDataSource { 
            return TasksLocalDataSource(
                database.taskDao(), ioDispatcher
            )
        }
    ...
    }

TasksRepositoryModule中`provideTasksRepository`，通过RemoteTasksDataSource等注解，就可以注入TasksDataSource了

/** * The binding for TasksRepository is on its own module so that we can replace it easily in tests. */
    @Module
    @InstallIn(ApplicationComponent::class)
    object TasksRepositoryModule { 
    
        @Singleton
        @Provides
        fun provideTasksRepository(
            @AppModule.RemoteTasksDataSource remoteTasksDataSource: TasksDataSource,
            @AppModule.LocalTasksDataSource localTasksDataSource: TasksDataSource,
            ioDispatcher: CoroutineDispatcher
        ): TasksRepository { 
            return DefaultTasksRepository(
                remoteTasksDataSource, localTasksDataSource, ioDispatcher
            )
        }
    }

## 单元测试 ##

我们配合SourceSet进行单元测试，将fake的测试类定义在SourceSet目录中，

@Module
    @InstallIn(ApplicationComponent::class)
    abstract class TestTasksRepositoryModule { 
        @Singleton
        @Binds
        abstract fun bindRepository(repo: FakeRepository): TasksRepository
    }

然后在实际代码中，通过`@UninstallModules`卸载业务对象，替换为测试对象

@RunWith(AndroidJUnit4::class)
    @MediumTest
    @ExperimentalCoroutinesApi
    // ** ↓UninstallModules将默认的业务对象删除，加载TestTasksRepositoryModule测试对象 **
    @UninstallModules(TasksRepositoryModule::class)
    @HiltAndroidTest
    class TasksFragmentTest {

# ActivityComponent #

--------------------

`@AndroidEntryPoint` 可以将Activity关联到`ActivityComponent`

@AndroidEntryPoint
    class TasksActivity : AppCompatActivity() {

Activity的中使用Navigation显示Fragment

//TasksActivity.kt
    val navController: NavController = findNavController(R.id.nav_host_fragment)
            appBarConfiguration =
                AppBarConfiguration.Builder(R.id.tasks_fragment_dest, R.id.statistics_fragment_dest)
                    .setDrawerLayout(drawerLayout)
                    .build()
            setupActionBarWithNavController(navController, appBarConfiguration)
            findViewById<NavigationView>(R.id.nav_view)
                .setupWithNavController(navController)

<fragment android:id="@+id/nav_host_fragment" android:name="androidx.navigation.fragment.NavHostFragment" android:layout_width="match_parent" android:layout_height="match_parent" app:defaultNavHost="true" app:navGraph="@navigation/nav_graph" />

<navigation xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:id="@+id/nav_graph" app:startDestination="@id/tasks_fragment_dest">
    　　 
    
        <fragment android:id="@+id/task_detail_fragment_dest" android:name="com.example.android.architecture.blueprints.todoapp.taskdetail.TaskDetailFragment" android:label="Task Details">
    ...
            <argument android:name="taskId" app:argType="string" />
    ...
        </fragment>
    　　 
        <fragment android:id="@+id/tasks_fragment_dest" android:name="com.example.android.architecture.blueprints.todoapp.tasks.TasksFragment" android:label="@string/app_name">
    ...
            <action android:id="@+id/action_tasksFragment_to_taskDetailFragment" app:destination="@id/task_detail_fragment_dest" />
    ...
        </fragment>

# FragmentComponent #

--------------------

@AndroidEntryPoint关联TasksFragment和`FragmentComponent`

@AndroidEntryPoint
    class TasksFragment : Fragment() { 
        private val viewModel by viewModels<TasksViewModel>()
        private val args: TasksFragmentArgs by navArgs()

TasksFragment的参数通过navigation的`navArgs`获取，显示任务列表，如下图：  
![20210101215323490.png][]

## 单元测试 ##

SourceSet中定义测试对象：

通过`HiltAndroidRule`，注入测试对象进行测试：

@RunWith(AndroidJUnit4::class)
    @MediumTest
    @ExperimentalCoroutinesApi
    // ** ①卸载业务对象 **
    @UninstallModules(TasksRepositoryModule::class)
    @HiltAndroidTest
    class TasksFragmentTest { 
    
        @get:Rule
        var hiltRule = HiltAndroidRule(this)
        // ② 根据HiltAndroidRule、注入FakeRepository
        @Inject
        lateinit var repository: TasksRepository
    
        @Before
        fun init() { 
            // Populate @Inject fields in test class
            hiltRule.inject()
        }

使用FakeRepository保存数据，并在TestCase中使用

@Test
        fun displayTask_whenRepositoryHasData() { 
            // GIVEN - One task already in the repository
            repository.saveTaskBlocking(Task("TITLE1", "DESCRIPTION1"))
    
            // WHEN - On startup
            launchActivity()
    
            // THEN - Verify task is displayed on screen
            onView(withText("TITLE1")).check(matches(isDisplayed()))
        }
    
        private fun launchActivity(): ActivityScenario<TasksActivity>? { 
            val activityScenario = launch(TasksActivity::class.java)
            activityScenario.onActivity {  activity ->
                // Disable animations in RecyclerView
                (activity.findViewById(R.id.tasks_list) as RecyclerView).itemAnimator = null
            }
            return activityScenario
        }

这里使用`launchFragmentInHiltContainer`启动Fragment

@Test
        fun clickAddTaskButton_navigateToAddEditFragment() { 
            // GIVEN - On the home screen
            val navController = mock(NavController::class.java)
    
            launchFragmentInHiltContainer<TasksFragment>(Bundle(), R.style.AppTheme) { 
                Navigation.setViewNavController(this.view!!, navController)
            }
    
            // WHEN - Click on the "+" button
            onView(withId(R.id.add_task_fab)).perform(click())
    
            // THEN - Verify that we navigate to the add screen
            verify(navController).navigate(
                TasksFragmentDirections.actionTasksFragmentToAddEditTaskFragment(
                    null, getApplicationContext<Context>().getString(R.string.add_task)
                )
            )
        }

Fragment的启动依赖Activity，构造`HiltTestActivity`帮助Fragment启动

/** * launchFragmentInContainer from the androidx.fragment:fragment-testing library * is NOT possible to use right now as it uses a hardcoded Activity under the hood * (i.e. [EmptyFragmentActivity]) which is not annotated with @AndroidEntryPoint. * * As a workaround, use this function that is equivalent. It requires you to add * [HiltTestActivity] in the debug folder and include it in the debug AndroidManifest.xml file * as can be found in this project. */
    inline fun <reified T : Fragment> launchFragmentInHiltContainer(
        fragmentArgs: Bundle? = null,
        @StyleRes themeResId: Int = R.style.FragmentScenarioEmptyFragmentActivityTheme,
        crossinline action: Fragment.() -> Unit = { }
    ) { 
        val startActivityIntent = Intent.makeMainActivity(
            ComponentName(
                ApplicationProvider.getApplicationContext(),
                HiltTestActivity::class.java
            )
        ).putExtra(EmptyFragmentActivity.THEME_EXTRAS_BUNDLE_KEY, themeResId)
    
        ActivityScenario.launch<HiltTestActivity>(startActivityIntent).onActivity {  activity ->
            val fragment: Fragment = activity.supportFragmentManager.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()
    
            fragment.action()
        }
    }

[https_github.com_android_architecture-samples_tree_dev-hilt]: https://github.com/android/architecture-samples/tree/dev-hilt
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3ZpdGF2aXZh_size_16_color_FFFFFF_t_70]: /images/20221120/490d2654734f48ef8d019e6ae6eca3e9.png
[https_developer.android.com_training_dependency-injection_hilt-android]: https://developer.android.com/training/dependency-injection/hilt-android
[20210101215323490.png]: /images/20221120/3586b7ba9ab04c50be240842042023e8.png