Mockito和AsyncTasks

Question

我在寫一些使用Mockito的測試。我有一個我想測試的類，基本上通過AsyncTask將同步調用變爲異步調用。

這是類測試：

public class GetEntryImpl implements GetEntry { 

    private final DataEntryRepository mDataEntryRepository; 

    public GetEntryImpl() { 
     this(new DataEntryRepositoryImpl()); 
    } 

    public GetEntryImpl(@NonNull final DataEntryRepository repository) { 
     mDataEntryRepository = repository; 
    } 

    @Override 
    public void execute(final long id, final Callback<DataEntry> callback) { 
     AsyncTask.execute(new Runnable() { 
      @Override 
      public void run() { 
       DataEntry dataEntry = mDataEntryRepository.getEntry(id); 
       if (dataEntry != null) { 
        callback.onResult(dataEntry); 
       } else { 
        callback.onError("TODO", null); 
       } 
      } 
     }); 
    } 
} 

這是我的測試：

public class GetEntryTest { 
    private GetEntryImpl mGetEntry; 
    @Mock 
    private DataEntryRepository mRepository; 
    @Captor 
    private ArgumentCaptor<Callback> mCallbackArgumentCaptor; 
    private DataEntry mDataEntry; 

    @Before 
    public void setup() throws Exception { 
     MockitoAnnotations.initMocks(this); 
     mDataEntry = getFakeEntry(); 
     when(mRepository.getEntry(anyLong())).thenReturn(mDataEntry); 
     mGetEntry = new GetEntryImpl(mRepository); 
    } 

    @SuppressWarnings("unchecked") 
    @Test 
    public void testGetEntry_success() throws Exception { 
     mGetEntry.execute(1L, mCallbackArgumentCaptor.capture()); 
     verify(mRepository).getEntry(eq(1L)); 
     Callback<DataEntry> callback = mCallbackArgumentCaptor.getValue(); 
     verify(callback).onResult(eq(mDataEntry)); 
    } 
} 

它讓我在運行測試時，這個錯誤（編輯：完整的堆棧跟蹤）：

org.mockito.exceptions.misusing.InvalidUseOfMatchersException: 
Misplaced argument matcher detected here: 

-> at com.xyz.interactor.GetEntryTest.testGetEntry_success(GetEntryTest.java:45) 

You cannot use argument matchers outside of verification or stubbing. 
Examples of correct usage of argument matchers: 
    when(mock.get(anyInt())).thenReturn(null); 
    doThrow(new RuntimeException()).when(mock).someVoidMethod(anyObject()); 
    verify(mock).someMethod(contains("foo")) 

Also, this error might show up because you use argument matchers with methods that cannot be mocked. 
Following methods *cannot* be stubbed/verified: final/private/equals()/hashCode(). 
Mocking methods declared on non-public parent classes is not supported. 


    at com.xyz.interactor.GetEntryTest.testGetEntry_success(GetEntryTest.java:46) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:498) 
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) 
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) 
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) 
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) 
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) 
    at org.robolectric.RobolectricTestRunner$2.evaluate(RobolectricTestRunner.java:251) 
    at org.robolectric.RobolectricTestRunner.runChild(RobolectricTestRunner.java:188) 
    at org.robolectric.RobolectricTestRunner.runChild(RobolectricTestRunner.java:54) 
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) 
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) 
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) 
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) 
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) 
    at org.robolectric.RobolectricTestRunner$1.evaluate(RobolectricTestRunner.java:152) 
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363) 
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137) 
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69) 
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234) 
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:498) 
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) 


Exception: java.lang.NullPointerException thrown from the UncaughtExceptionHandler in thread "AsyncTask #1" 

Process finished with exit code 255 

45行是測試的第一行：

mGetEntry.execute(1L, mCallbackArgumentCaptor.capture()); 

Answer 1

對於Callback，您不需要ArgumentCaptor，而是一個模擬。

@SuppressWarnings("unchecked") 
@Test 
public void testGetEntry_success() throws Exception { 
    mGetEntry.execute(1L, mCallback); 
    verify(mRepository).getEntry(eq(1L)); 
    verify(mCallback).onResult(eq(mDataEntry)); 
} 

其中mCallback是：由於您使用的是ArgumentCaptor外verify聲明

@Mock 
private Callback<DataEntry> mCallback; 

打印的Mockito錯誤。您可以看到正確的ArgumentCaptor使用示例here。