# Unit Test - 使用hilt測試7 - Testing Navigation

---

## 開始吧

### 情境
* 要透過UI操作，驗證測試頁面是否正確導航至指定的頁面
* Espresso 主要模擬UI的操作
* Mockito 產生假物件與驗證

### res底下新增nev_graph
* 新增Destination並加入action
* 設定navHost

// activity_main.xml

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

### 設定對應的navigate action
* 設定shoppingFragment導航至addShoppingItemFragment的觸發按鈕

class ShoppingFragment : Fragment(R.layout.fragment_shopping) {

    lateinit var viewModel: ShoppingViewModel

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        viewModel = ViewModelProvider(requireActivity()).get(ShoppingViewModel::class.java)

        //對floating button設置點擊事件->觸發導航至下一個頁面
        fabAddShoppingItem.setOnClickListener {
            findNavController().navigate(
                ShoppingFragmentDirections.actionShoppingFragmentToAddShoppingItemFragment())
        }
    }
}


* 設定addShoppingItemFragment導航至imagePickFragment的觸發listener

class AddShoppingItemFragment: Fragment(R.layout.fragment_add_shopping_item) {

    lateinit var viewModel: ShoppingViewModel

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        viewModel = ViewModelProvider(requireActivity()).get(ShoppingViewModel::class.java)

        //設定對應的導航listener
        ivShoppingImage.setOnClickListener {
            findNavController().navigate(
                AddShoppingItemFragmentDirections.actionAddShoppingItemFragmentToImagePickFragment()
            )
        }
        //註冊callback在按返回鍵，自動清空ImageUrl
        val callback = object : OnBackPressedCallback(true){
            override fun handleOnBackPressed() {
                viewModel.setCurImageUrl("")
                findNavController().popBackStack()
            }
        }
        requireActivity().onBackPressedDispatcher.addCallback(callback)
    }
}

### 寫測試吧
1. **測試shoppingFragment到addShoppingFragment頁面**
* 使用mockito做一個mock的navController
* 再使用上一篇的launchFragmentInHiltContainer建立含有@Android Entry Point的fragment
* 再將navController和fragment做連結，就可以透過controller控制這個fragment與其childView
* 使用Espresso指定UI的元件與其action，這邊我們指向到floating button 執行click
* 使用verify驗證我們mock的navController中，navigate方法是不是導航至我們所指定的

@MediumTest
@HiltAndroidTest
@ExperimentalCoroutinesApi
class ShoppingFragmentTest {

    @get:Rule
    var hiltRule = HiltAndroidRule(this)

    @Before
    fun setup() {
        hiltRule.inject()
    }

    @Test
    fun clickAddShoppingItemButton_navigateToAddShoppingItemFragment() {
        val navController = mock(NavController::class.java)
        launchFragmentInHiltContainer<ShoppingFragment> {
            Navigation.setViewNavController(requireView(), navController)
        }

        onView(withId(R.id.fabAddShoppingItem)).perform(click())

        verify(navController).navigate(
            ShoppingFragmentDirections.actionShoppingFragmentToAddShoppingItemFragment()
        )
    }
}

2. **測試addShoppingFragment到imagePickFragment頁面**
* 驗證popBackStack是否有正確執行
* 驗證點選ivShoppingImage是否正確導航到指定頁面

@ExperimentalCoroutinesApi
@MediumTest
@HiltAndroidTest
class AddShoppingItemFragmentTest {

    @get:Rule
    var hiltRule = HiltAndroidRule(this)

    @Before
    fun setup(){
        hiltRule.inject()
    }

    @Test
    fun pressBackButton_popBackStack(){
        val navController = Mockito.mock(NavController::class.java)
        launchFragmentInHiltContainer<AddShoppingItemFragment> {
            Navigation.setViewNavController(requireView(), navController)
        }

        pressBack()

        verify(navController).popBackStack()
    }
    
    @Test
    fun clickivShoppingImage_navigeteToImagePickFragment(){
        val navController = Mockito.mock(NavController::class.java)
        launchFragmentInHiltContainer<AddShoppingItemFragment> {
            Navigation.setViewNavController(requireView(), navController)
        }

        //指定ivShoppingImage執行click動作
        onView(withId(R.id.ivShoppingImage)).perform(click())

        //驗證是否導航至指定頁面
        verify(navController).navigate(
           AddShoppingItemFragmentDirections.actionAddShoppingItemFragmentToImagePickFragment()
        )
    }
}

3. **額外驗證popBackStack之後curImageUrl是否設定為empty**
* 在測試viewModel有介紹使用假的repo實例viewModel
* 所以要把之前在test寫的fakeRepository複製到AndroidTest這邊的路徑
* 因為curImageUrl是在背景執行緒更改，所以要加入Rule
* mock AddShoppingItemFragment並將我們使用fakeRepository產生的實例指派給mock的fragment內的viewModel
* 執行pressBack()之後驗證curImageUrl這個liveData的值是否為空

@get:Rule
    var instantTaskExecutorRule = InstantTaskExecutorRule()

@Test
    fun imageUrlIsEmpty_afterPooBackStack(){
        val testviewModel = ShoppingViewModel(FakeRepository())

        val navController = mock(NavController::class.java)
        launchFragmentInHiltContainer<AddShoppingItemFragment> {
            Navigation.setViewNavController(requireView(), navController)
            viewModel = testviewModel
        }
        pressBack()
        val value = testviewModel.curImageUrl.getOrAwaitValue()
        assertThat(value).isEmpty()

    }

參考資料
[
Philipp Lackner's channel](https://www.youtube.com/watch?v=uUmFfZDoOTY)

###### tags: `test` `Unit Test` `kotlin`