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我正在尝试为使用 ViewBinding 的 RecyclerView.ViewHolder 类编写单元测试，但我在测试类中膨胀 ViewBinding 时遇到问题，在运行测试时出现此错误： Binary XML file line #38: Binary XML file line #38: Error inflating class <unknown> Caused by: java.lang.UnsupportedOperationException: Failed to resolve attribute at index 5: TypedValue{t=0x2/d=0x7f04015d a=2}

我在测试类中找不到 ViewBinding inflate 的代码示例，这可能吗？我找到了这个 StackOverflow 线程，但它使用 PowerMock 来模拟 ViewBinding 类。我在我的项目中使用 mockK，我认为在我的情况下使用真正的 ViewBinding 实例会更好。

我的 ViewHolder 看起来像这样：

class MemoViewHolder(private val binding: MemoItemBinding) : RecyclerView.ViewHolder(binding.root) {
   
    fun bind(data: Memo) {
        with(binding) {
            // doing binding with rules I would like to test
        }
    }
}

我的测试课看起来像这样。我正在使用MockK和Robolectric来获取应用程序上下文

@RunWith(RobolectricTestRunner::class)
class MemoViewHolderTest {

    private lateinit var context: MyApplication

    @Before
    fun setUp() {
        MockKAnnotations.init(this)
        context = ApplicationProvider.getApplicationContext()
    }

    @Test
    fun testSuccess() {
        val viewGroup = mockk<ViewGroup>(relaxed = true)
        val binding = MemoItemBinding.inflate(LayoutInflater.from(context), viewGroup, false)
    }
}

编辑：这是来自@tyler-v 的答案的 mockK 版本

@RelaxedMockK
private lateinit var layoutInflater: LayoutInflater
@RelaxedMockK
private lateinit var rootView: ConstraintLayout // must be the type of the root view in the layout
@RelaxedMockK
private lateinit var groupView: ViewGroup
// mock every views in your layout
@RelaxedMockK
private lateinit var title: TextView

@Before
fun setUp() {
    context = ContextThemeWrapper(
        ApplicationProvider.getApplicationContext<MyApplication>(),
        R.style.AppTheme
    )
    MockKAnnotations.init(this)
    every { layoutInflater.inflate(R.layout.memo_item, groupView, false) } returns rootView
    every { rootView.childCount } returns 1
    every { rootView.getChildAt(0) } returns rootView
    // mock findViewById for each view in the memo_item layout
    every { rootView.findViewById<TextView>(R.id.title) } returns title
}

@After
fun tearDown() {
    unmockkAll()
}

@Test
fun testBindUser() {
    val binding = MemoItemBinding.inflate(layoutInflater, groupView, false)
    MemoListAdapter.MemoViewHolder(binding).bind(memoList[0])
    // some tests...
}
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1 回答 1

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通过查看生成的绑定类以查看我需要模拟哪些方法以使其膨胀并正确返回模拟视图，我能够得到这个工作（使用Mockito，但它也应该适用于MockK ）。这些文件app/build/generated/data_binding_base_class_source_out/debug/out/your/package/databinding用于标准构建

下面是一个在 ConstraintLayout 中生成具有三个视图的数据绑定类的示例。

public final class ActivityMainBinding implements ViewBinding {
  @NonNull
  private final ConstraintLayout rootView;

  @NonNull
  public final Button getText;

  @NonNull
  public final ProgressBar progress;

  @NonNull
  public final TextView text;

  private ActivityMainBinding(@NonNull ConstraintLayout rootView, @NonNull Button getText,
      @NonNull ProgressBar progress, @NonNull TextView text) {
    this.rootView = rootView;
    this.getText = getText;
    this.progress = progress;
    this.text = text;
  }

  @Override
  @NonNull
  public ConstraintLayout getRoot() {
    return rootView;
  }

  @NonNull
  public static ActivityMainBinding inflate(@NonNull LayoutInflater inflater) {
    return inflate(inflater, null, false);
  }

  @NonNull
  public static ActivityMainBinding inflate(@NonNull LayoutInflater inflater,
      @Nullable ViewGroup parent, boolean attachToParent) {
    View root = inflater.inflate(R.layout.activity_main, parent, false);
    if (attachToParent) {
      parent.addView(root);
    }
    return bind(root);
  }

  @NonNull
  public static ActivityMainBinding bind(@NonNull View rootView) {
    // The body of this method is generated in a way you would not otherwise write.
    // This is done to optimize the compiled bytecode for size and performance.
    int id;
    missingId: {
      id = R.id.get_text;
      Button getText = ViewBindings.findChildViewById(rootView, id);
      if (getText == null) {
        break missingId;
      }

      id = R.id.progress;
      ProgressBar progress = ViewBindings.findChildViewById(rootView, id);
      if (progress == null) {
        break missingId;
      }

      id = R.id.text;
      TextView text = ViewBindings.findChildViewById(rootView, id);
      if (text == null) {
        break missingId;
      }

      return new ActivityMainBinding((ConstraintLayout) rootView, getText, progress, text);
    }
    String missingId = rootView.getResources().getResourceName(id);
    throw new NullPointerException("Missing required view with ID: ".concat(missingId));
  }
}

为了能够调用 inflate 并使绑定在单元测试中保持模拟视图，您需要模拟几组调用

@Before
fun setUp() {
    // return the mock root from the mock inflater
    doReturn(mMockConvertView).`when`(mMockInflater).inflate(R.layout.my_layout, mMockViewGroup, false)
    
    // extra mocks to handle findChildViewById
    doReturn(1).`when`(mMockConvertView).childCount
    doReturn(mMockConvertView).`when`(mMockConvertView).getChildAt(0)

    // Return the mocked views
    doReturn(mMockText).`when`(mMockConvertView).findViewById<View>(R.id.text)
    doReturn(mMockButton).`when`(mMockConvertView).findViewById<View>(R.id.get_text)
    doReturn(mMockProgBar).`when`(mMockConvertView).findViewById<View>(R.id.progress)
}

他们最近将其更改为 useViewBindings.findChildViewById而不是 just findViewById，这需要额外的模拟。

@Nullable
public static <T extends View> T findChildViewById(View rootView, @IdRes int id) {
    if (!(rootView instanceof ViewGroup)) {
        return null;
    }
    final ViewGroup rootViewGroup = (ViewGroup) rootView;
    final int childCount = rootViewGroup.getChildCount();
    for (int i = 0; i < childCount; i++) {
        final T view = rootViewGroup.getChildAt(i).findViewById(id);
        if (view != null) {
            return view;
        }
    }
    return null;
}

请记住，它们将来可能会更改自动生成代码的结构，这将破坏这样的单元测试。这发生在最近，当他们切换到这种静态方法时，如果将来再次发生，我也不会感到惊讶。

定义了这些，然后你可以调用

val binding = ActivityMainBinding.inflate(mMockInflater, mMockViewGroup, false)

获得一个实际的绑定实例来保存你的模拟视图。

于 2021-12-15T13:55:48.350 回答