使用Mockito多次调用具有相同参数的相同方法

Question

有没有办法让stubbed方法在后续调用中返回不同的对象？我想这样做来测试一个非确定的响应ExecutorCompletionService.即,无论方法的返回顺序如何进行测试,结果都保持不变.

我想要测试的代码看起来像这样.

// Create an completion service so we can group these tasks together
ExecutorCompletionService<T> completionService =
        new ExecutorCompletionService<T>(service);

// Add all these tasks to the completion service
for (Callable<T> t : ts)
    completionService.submit(request);

// As an when each call finished, add it to the response set.
for (int i = 0; i < calls.size(); i ++) {
    try {
        T t = completionService.take().get();
        // do some stuff that I want to test
    } catch (...) { }        
}

Answer 1

怎么样

when( method-call ).thenReturn( value1, value2, value3 );

您可以在thenReturn的括号中添加任意数量的参数,前提是它们都是正确的类型.第一次调用方法时将返回第一个值,然后是第二个答案,依此类推.所有其他值用完后,将重复返回最后一个值.

Answer 2

您可以使用该thenAnswer方法(链接时when):

when(someMock.someMethod()).thenAnswer(new Answer() {
    private int count = 0;

    public Object answer(InvocationOnMock invocation) {
        if (count++ == 1)
            return 1;

        return 2;
    }
});

或者使用等效的静态doAnswer方法:

doAnswer(new Answer() {
    private int count = 0;

    public Object answer(InvocationOnMock invocation) {
        if (count++ == 1)
            return 1;

        return 2;
    }
}).when(someMock).someMethod();

Answer 3

如前所述,几乎所有的呼叫都是可链接的.

所以你可以打电话

when(mock.method()).thenReturn(foo).thenReturn(bar).thenThrow(new Exception("test"));

//OR if you're mocking a void method and/or using spy instead of mock

doReturn(foo).doReturn(bar).doThrow(new Exception("Test").when(mock).method();

更多信息在Mockito的文件中.

Answer 4

你甚至可以doReturn()像这样链接方法调用

doReturn(null).doReturn(anotherInstance).when(mock).method();

可爱不是:)

Answer 5

BDD风格：

import static org.mockito.BDDMockito.given;
        ...

        given(yourMock.yourMethod()).willReturn(1, 2, 3);

经典款式：

import static org.mockito.Mockito.when;
        ...

        when(yourMock.yourMethod()).thenReturn(1, 2, 3);

显式风格：

        ...

        when(yourMock.yourMethod())
            .thenReturn(1)
            .thenReturn(2)
            .thenReturn(3);

Answer 6

我已经实现了一个MultipleAnswer类，可以帮助我在每次调用中存根不同的答案。这是一段代码：

private final class MultipleAnswer<T> implements Answer<T> {

    private final ArrayList<Answer<T>> mAnswers;

    MultipleAnswer(Answer<T>... answer) {
        mAnswers = new ArrayList<>();
        mAnswers.addAll(Arrays.asList(answer));
    }

    @Override
    public T answer(InvocationOnMock invocation) throws Throwable {
        return mAnswers.remove(0).answer(invocation);
    }
}