Mockito参数匹配器误用问题：全Mock仍报错求助

问题描述 #

我理解Mockito要求方法参数要么全用匹配器，要么全用原始值，但我的测试代码已尝试使用Mock，却仍抛出错误：Invalid use of argument matchers! 0 matchers expected, 4 recorded。以下是测试代码和业务代码：

测试代码 #

@ExtendWith(MockitoExtension.class)
public class GroupServiceImplTest extends TraceUtilsTest {

    @InjectMocks
    private GroupServiceImpl groupService;

    @InjectMocks
    private ClientRequest clientRequest;

    @Test
    public void shouldThrowHttpExceptionIfDeletionails(){
        Mockito.when(clientRequest.getAPIResponseUsingDeleteMethod(anyString(),
            Mockito.any(Mono.class), Mockito.eq(Request.class),
            Mockito.eq(Response.class))).thenReturn(Mono.error(new HttpServerErrorException(HttpStatus.BAD_REQUEST,
            "Abandoning r")));
        StepVerifier.create(groupService.deleteDataFromUpStream("123",List.of("123")))
            .expectErrorMatches(exception -> exception instanceof HttpClientErrorException && exception.getMessage().contains("Abandoning retrying as Error code is 4xx:"))
            .verify();
    }
}

业务代码 #

public Mono<GroupDetailsResponse> deleteDataFromUpStream(final String groupName, final List<String> groupData) {
    return deleteGroup(groupName, groupData);
}

private Mono<GroupDetailsResponse> deleteGroup(String groupName, List<String> groupData) {
    return  clientRequest.getAPIResponseUsingDeleteMethod(new StringBuilder("baseurl")
                                                                    .append("prodgroupPath")
                                                                    .append("/")
                                                                    .append(groupName)
                                                                    .toString(),
                                                                    GroupRequest.groupData(groupData).build(),
                                                                    GroupRequest.class,
                                                                    GroupDetailsResponse.class
                                                );
}

问题原因与解决办法 #

• ClientRequest未被正确Mock
  你给ClientRequest标注了@InjectMocks，这会让Mockito尝试创建该类的真实实例，而非Mock对象。参数匹配器（如anyString()、any()）仅能用于Mock对象的方法调用，对真实对象使用匹配器会直接触发该错误。

• 参数匹配器与实际调用类型不匹配
  测试代码中第二个参数用了Mockito.any(Mono.class)，但业务代码传入的是GroupRequest实例，类型不匹配会导致匹配失败，同时加重参数匹配器的使用错误。

修正后的测试代码 #

@ExtendWith(MockitoExtension.class)
public class GroupServiceImplTest extends TraceUtilsTest {

    @InjectMocks
    private GroupServiceImpl groupService;

    // 将@InjectMocks改为@Mock，创建ClientRequest的Mock实例
    @Mock
    private ClientRequest clientRequest;

    @Test
    public void shouldThrowHttpExceptionIfDeletionFails(){
        // 修正第二个参数的匹配器，与业务代码传入的GroupRequest类型对应
        Mockito.when(clientRequest.getAPIResponseUsingDeleteMethod(anyString(),
            Mockito.any(GroupRequest.class), Mockito.eq(GroupRequest.class),
            Mockito.eq(GroupDetailsResponse.class))).thenReturn(Mono.error(new HttpServerErrorException(HttpStatus.BAD_REQUEST,
            "Abandoning r")));
        StepVerifier.create(groupService.deleteDataFromUpStream("123",List.of("123")))
            .expectErrorMatches(exception -> exception instanceof HttpClientErrorException && exception.getMessage().contains("Abandoning retrying as Error code is 4xx:"))
            .verify();
    }
}

内容的提问来源于stack exchange，提问作者LowCool