使用Mockito与具有相同参数的多次调用相同方法

Question

有没有一种方法可以使存根方法在后续调用中返回不同的对象？我想这样做是为了测试来自的不确定响应ExecutorCompletionService。即，不管方法的返回顺序如何进行测试，结果都保持恒定。

我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

你可以使用thenAnswer方法来做到这一点（与链接时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();