Mockito - MissingMethodInvocationException

Question

我想測試一個API調用安排在正確的調度程序，並觀察主線程。

@RunWith(PowerMockRunner.class) 
@PrepareForTest({Observable.class, AndroidSchedulers.class}) 
public class ProductsPresenterTest { 

    private ProductsPresenter presenter; 
    @Before 
    public void setUp() throws Exception{ 
     presenter = spy(new ProductsPresenter(mock(SoajsRxRestService.class))); 
    } 


    @Test 
    public void testShouldScheduleApiCall(){ 
     Observable productsObservable = mock(Observable.class); 
     CatalogSearchInput catalogSearchInput = mock(CatalogSearchInput.class); 
     when(presenter.soajs.getProducts(catalogSearchInput)).thenReturn(productsObservable); 

     /* error here*/ 
     when(productsObservable.subscribeOn(Schedulers.io())).thenReturn(productsObservable); 
     when(productsObservable.observeOn(AndroidSchedulers.mainThread())).thenReturn(productsObservable); 
     presenter.loadProducts(catalogSearchInput); 

     //verify if all methods in the chain are called with correct arguments 
     verify(presenter.soajs).getProducts(catalogSearchInput); 
     verify(productsObservable).subscribeOn(Schedulers.io()); 
     verify(productsObservable).observeOn(AndroidSchedulers.mainThread()); 
     verify(productsObservable).subscribe(Matchers.<Subscriber<Result<Catalog<SoajsProductPreview>>>>any()); 
    } 
} 

線

when(productsObservable.subscribeOn(Schedulers.io())).thenReturn(productsObservable); 

拋出以下異常，並我不明白爲什麼，因爲productObservable是一個模擬。任何想法或類似的經驗？

org.mockito.exceptions.misusing.MissingMethodInvocationException: 
when() requires an argument which has to be 'a method call on a mock'. 
For example: 
    when(mock.getArticles()).thenReturn(articles); 

Also, this error might show up because: 
1. you stub either of: final/private/equals()/hashCode() methods. 
    Those methods *cannot* be stubbed/verified. 
    Mocking methods declared on non-public parent classes is not supported. 
2. inside when() you don't call method on mock but on some other object. 

Answer 1

問題是由於Observable :: subscribeOn是最終的方法，其中Mockito can't mock。 一個可能的解決方案是使用Powermock：

@RunWith(PowerMockRunner.class) 
@PrepareForTest(Observable.class) 
public class MockTest { 
    @Test 
    public void test() { 
     Observable productsObservable = PowerMockito.mock(Observable.class); 

     when(productsObservable.subscribeOn(null)).thenReturn(productsObservable); 
     productsObservable.subscribeOn(null); 
     verify(productsObservable).subscribeOn(null); 
    } 
}