java - Mockito 在 Spy 上使用 doAnswer

Question

我想使用 when(spy).thenAnswer(new Answer())但似乎 thenAnswer 只适用于模拟而不适用于 spy 。我想使用 spy ，因为我只想 stub 特定方法。

有没有办法对 spy 对象进行回答？

Answer 1

如官方 documentation 所述，这是可能的，有时甚至建议:

Important gotcha on spying real objects!

Sometimes it's impossible or impractical to use when(Object) for stubbing spies. Therefore when using spies please consider doReturn|Answer|Throw() family of methods for stubbing.

但是，再次作为 doc状态:

Stubbing voids requires different approach from when(Object) because the compiler does not like void methods inside brackets...

你的方法无效吗？

文档中的示例如果无效:

doAnswer(new Answer() {
    public Object answer(InvocationOnMock invocation) {
        Object[] args = invocation.getArguments();
        Mock mock = invocation.getMock();
        return null;
    }
}).when(mock).someMethod();

因此，如果您的方法无效，您应该使用以下代码:

MyObject spy = spy(myObject);

doAnswer(new Answer<Object>() {
    @Override
    public Object answer(InvocationOnMock invocation) throws Throwable {
        return null;
    }
}).when(spy).notify();   

或者如果它不是空的:

when(spy.toString()).thenAnswer(new Answer<String>() {
    @Override
    public String answer(InvocationOnMock invocation) throws Throwable {
        return "this";
    }
});