Mock测试返回值为空的方法

要测试的类

@Service
public class NirvanaDecorationLinesClassHistoryServiceImpl implements NirvanaDecorationLinesClassHistoryService {
    @Autowired
    private NirvanaDecorationLinesClassHistoryMapper mapper;

    /**
     * 插入数据
     *
     * @param decorationLinesClassHistoryDo
     */
    @Override
    public void insertClass(NirvanaDecorationLinesClassHistoryDO decorationLinesClassHistoryDo) {
        mapper.insertClass(decorationLinesClassHistoryDo);
    }
}

测试类

@RunWith(MockitoJUnitRunner.Silent.class)
public class NirvanaDecorationLinesClassHistoryServiceImplTest {
    @InjectMocks
    private NirvanaDecorationLinesClassHistoryServiceImpl service;
    @Mock
    private NirvanaDecorationLinesClassHistoryMapper mapper;

    @Test
    public void insertClass() {
        NirvanaDecorationLinesClassHistoryDO decorationLinesClassHistoryDo = new NirvanaDecorationLinesClassHistoryDO();
        Mockito.doNothing().when(mapper).insertClass(decorationLinesClassHistoryDo);
        service.insertClass(decorationLinesClassHistoryDo);
        Assert.assertTrue("decorationLinesClassHistoryDo is null", !ObjectUtils.isEmpty(decorationLinesClassHistoryDo));
    }
}