使用 Mockito 单独测试片段 class

Question

已添加 @VisibleForTesting 并受到保护。我的测试现在可以用这个方法：

   @VisibleForTesting
    protected void setupDataBinding(List<Recipe> recipeList) {
        recipeAdapter = new RecipeAdapter(recipeList);
        RecyclerView.LayoutManager layoutManager
                = new LinearLayoutManager(getActivity(), LinearLayoutManager.VERTICAL, false);
        rvRecipeList.setLayoutManager(layoutManager);
        rvRecipeList.setAdapter(recipeAdapter);
    }

使用间谍对象更新了测试用例：但是，即使我创建了一个将被调用的间谍模拟，也会调用真正的 setupDataBinding(recipe)。也许我做错了。

@Test
public void testShouldGetAllRecipes() {
    RecipeListView spy = Mockito.spy(fragment);
    doNothing().when(spy).setupDataBinding(recipe);

    fragment.displayRecipeData(recipe);

    verify(recipeItemClickListener, times(1)).onRecipeItemClick();
}

我正在尝试测试 Fragment class 中的方法，如下所示。但是，我正在尝试模拟这些方法以验证这些方法被调用的次数是否正确。但是，问题是我有一个 private 方法 setupDataBinding(...) 设置在从 displayRecipeData(...) 调用的 RecyclerView 上。我想模拟这些调用，因为我不想调用 RecyclerView 上的真实对象。我只想验证 setupDataBinding(...) 是否被调用。

我尝试过使用间谍和 VisibleForTesting，但仍然不确定如何使用。

我正在尝试单独测试 Fragment。

public class RecipeListView
        extends MvpFragment<RecipeListViewContract, RecipeListPresenterImp>
        implements RecipeListViewContract {

    @VisibleForTesting
    private void setupDataBinding(List<Recipe> recipeList) {
        recipeAdapter = new RecipeAdapter(recipeList);
        RecyclerView.LayoutManager layoutManager
                = new LinearLayoutManager(getActivity(), LinearLayoutManager.VERTICAL, false);
        rvRecipeList.setLayoutManager(layoutManager);
        rvRecipeList.setAdapter(recipeAdapter);
    }

    @Override
    public void displayRecipeData(List<Recipe> recipeList) {
        /* Verify this get called only once */
        setupDataBinding(recipeList);

        recipeItemListener.onRecipeItem();
    }
}

这就是我正在测试的方式。我添加了 VisibleForTesting 认为我可以提供帮助。我试过使用间谍。

public class RecipeListViewTest {
    private RecipeListView fragment;
    @Mock RecipeListPresenterContract presenter;
    @Mock RecipeItemListener recipeItemListener;
    @Mock List<Recipe> recipe;

    @Before
    public void setup() {
        MockitoAnnotations.initMocks(RecipeListViewTest.this);
        fragment = RecipeListView.newInstance();
    }

    @Test
    public void testShouldGetAllRecipes() {
        fragment.displayRecipeData(recipe);
        RecipeListView spy = Mockito.spy(fragment);

        verify(recipeItemListener, times(1)).onRecipeItem();
    }
}

单独测试上述内容的最佳方法是什么？

非常感谢您的任何建议。

Answer 1

为了防止真正的方法被调用使用：Mockito.doNothing().when(spy).onRecipeItem();

这里有最少的使用示例：

public class ExampleUnitTest {
    @Test
    public void testSpyObject() throws Exception {
        SpyTestObject spyTestObject = new SpyTestObject();
        SpyTestObject spy = Mockito.spy(spyTestObject);

        Mockito.doNothing().when(spy).methodB();

        spy.methodA();
        Mockito.verify(spy).methodB();
    }

    public class SpyTestObject {

        public void methodA() {
            methodB();
        }
        public void methodB() {
            throw new RuntimeException();
        }
    }

}

Answer 2

I want to mock these calls as I don't want to call the real object on the RecyclerView. I just want to verify, that setupDataBinding() gets called.

您还没有创建足够的接缝来执行此操作。

如果您声明一个描述 "setup data binding" 将如何发生的合同怎么办？换句话说，如果您使用方法 void setupDataBinding(...) 创建一个接口会怎样？然后 RecipeListView 将持有该接口的一个实例作为依赖项。因此，RecipeListView 永远不会知道这个设置将如何进行：它知道一件事 - 他拥有的依赖关系 "signed the contract" 并负责执行这项工作。

通常，您会通过构造函数传递该依赖项，但是因为 Fragment is a specific case, you can acquire dependencies in onAttach():

interface Setupper {
    void setupDataBinding(List<Recipe> recipes, ...);
}

class RecipeListView extends ... {

    Setupper setupper;

    @Override public void onAttach(Context context) {
        super.onAttach(context);

        // Better let the Dependency Injection tool (e.g. Dagger) provide the `Setupper`
        // Or initialize it here (which is not recommended)
        Setupper temp = ...
        initSetupper(temp);
    }

    void initSetupper(Setupper setupper) {
        this.setupper = setupper;
    }

    @Override
    public void displayRecipeData(List<Recipe> recipes) {
        // `RecipeListView` doesn't know what exactly `Setupper` does
        // it just delegates the work
        setupper.setupDataBinding(recipes, ...);

        recipeItemListener.onRecipeItem();
    }
}

这给了你什么？现在你有一个接缝。现在您不依赖实施，您依赖合同。

public class RecipeListViewTest {

    @Mock Setupper setupper;
    List<Recipe> recipe = ...; // initialize, no need to mock it
    ...

    private RecipeListView fragment;

    @Before
    public void setup() {
        MockitoAnnotations.initMocks(this);
        fragment = new RecipeListView();
        fragment.initSetupper(setupper);
    }

    @Test
    public void testShouldGetAllRecipes() {
        fragment.displayRecipeData(recipes);

        // You do not care what happens behind this call
        // The only thing you care - is to test whether is has been executed
        verify(setupper).setupDataBinding(recipe, ...);
        // verify(..) is the same as verify(.., times(1))
    }
}

我强烈推荐 Misko Hevery's "Writing Testable Code" 这本书，它通过示例以简明的方式说明了所有技术（38 页）。

Answer 3

有一个普遍的经验法则：测试单位的功能比测试它的工作方式要好得多。

考虑到这一点问自己一个问题 - 为什么我首先要模拟 setupDataBinding 方法？它不进行任何外部调用，它只更改对象的状态。因此，测试此代码的更好方法是检查它是否以正确的方式更改状态：

@Test
public void testShouldGetAllRecipes() {
     fragment.displayRecipeData(recipeList);

     // Verifies whether RecipeAdapter has been initialized correctly
     RecipeAdapter recipeAdapter = fragment.getRecipeAdapter();
     assertNotNull(recipeAdapter);
     assertSame(recipeList, recipeAdapter.getRecipeList());

     // Verifies whethr RvRecipeList has been initialized correctly 
     RvRecipeList rvRecipeList = fragment.getRvRecipeList();
     assertNotNull(rvRecipeList);
     assertNotNull(rvRecipeList.getLayoutManager());
     assertSame(fragment.getRecipeAdapter(), rvRecipeList.getAdapter());
}

这可能需要添加几个 getters/setters 以使整个事情更易于测试。

使用 Mockito 单独测试片段 class

Testing a Fragment class in isolation using Mockito

java

android

unit-testing

mockito

android-testing