java - 获取 "InvalidUseOfMatchersException"，即使它被正确使用

Question

我有以下模拟对象:

@Mock
ObjectMapper objectMapper = new ObjectMapper();

然后我写了一些 mock 逻辑，声称我做错了:

Mockito.when(objectMapper.writeValueAsString(Mockito.anyObject())).thenThrow(JsonProcessingException.class);

我哪里出错了？

Answer 1

Matcher methods like anyObject(), eq() do not return matchers. Internally, they record a matcher on a stack and return a dummy value (usually null). This implementation is due to static type safety imposed by the java compiler. The consequence is that you cannot use anyObject(), eq() methods outside of verified/stubbed method.

我的建议是使用any()

例如

@Test
public void TestObjectMapper() {
    //Arrange
    ObjectMapper objectMapper = mock(ObjectMapper.class);
    when(objectMapper.writeValueAsString(any()))
        .thenThrow(new JsonProcessingException());

    //...
}