调用模拟对象的方法时如何验证返回值

Question

使用 Mockito，有没有办法对对象进行 spy() 并验证对象是否使用指定的参数被调用了给定的 # 次，并且它是否为这些调用返回了预期值？

我想做如下的事情：

class HatesTwos {
  boolean hates(int val) {
    return val == 2;
  }
}

HatesTwos hater = spy(new HatesTwos());
hater.hates(1);
assertFalse(verify(hater, times(1)).hates(1));

reset(hater);
hater.hates(2);
assertTrue(verify(hater, times(1)).hates(2));

Answer 1

您可以使用Answer 接口来捕获真正的响应。

public class ResultCaptor<T> implements Answer {
    private T result = null;
    public T getResult() {
        return result;
    }

    @Override
    public T answer(InvocationOnMock invocationOnMock) throws Throwable {
        result = (T) invocationOnMock.callRealMethod();
        return result;
    }
}

预期用途：

class HatesTwos {
    boolean hates(int val) {
        return val == 2;
    }
}

HatesTwos hater = spy(new HatesTwos());

// let's capture the return values from hater.hates(int)
ResultCaptor<Boolean> hateResultCaptor = new ResultCaptor<>();
doAnswer(hateResultCaptor).when(hater).hates(anyInt());

hater.hates(1);
verify(hater, times(1)).hates(1);
assertFalse(hateResultCaptor.getResult());

reset(hater);

hater.hates(2);
verify(hater, times(1)).hates(2);
assertTrue(hateResultCaptor.getResult());