通过lambda和mockito answer提升单元测试效率

各位好,今天小编会向大家介绍一下通过lambda和mockito answer提升单元测试编写效率的方法,如果你受够了各种复杂的依赖,如果你受够了写重复冗余的单测代码,如果你想解放双手,成就人生梦想,那么请往下看。

一、前提背景

大家在测试Spring RestTemplate的时候,为了规避上下文带来的影响且保证单元测试的效率与独立性,使用mock技术是常用的手法。但是实际项目中,如果要从RestTemplate转为其他框架的时候,就需要修改所有的单元测试代码,也就是说,目前的代码还是依赖于框架的,还是不够独立:

  public class SpringCloudRefactoringTest {

      private static final Long EXISTING_VARIA = 1L;

      private static final Map GOOD_HTTP_PARAMS = Collections.singletonMap("id", EXISTING_VARIA);

      private static final Long NON_EXISTING_VARIA = 15123123L;

      private static final Map NON_EXISTING_HTTP_PARAMS = Collections.singletonMap("id", NON_EXISTING_VARIA);

      private static final Long OVER_VARIA = 99999999L;

      private static final Map BAD_HTTP_PARAMS = Collections.singletonMap("id", BAD_VARIA);

      private static final ResponseEntity ERROR_RESPONSE =

              new ResponseEntity<>(new SpringCloudFactResponse("NoSuchQuoteException", "No quote with id=15123123."), HttpStatus.OK);

      private static final ResponseEntity ITEM_RESPONSE =

              new ResponseEntity<>(new SpringCloudFactResponse("success", new SpringCloudFact(1L, "OK")), HttpStatus.OK);

      @Test

      public void serviceShouldReturnFact() {

          RestTemplate restTemplate = mock(RestTemplate.class);

          when(restTemplate.getForEntity(FACT_URL, SpringCloudFactResponse.class, GOOD_HTTP_PARAMS))

                  .thenReturn(ITEM_RESPONSE);

          SpringCloudService myServiceUnderTest = new SpringCloudService(restTemplate);

          SpringCloudFact springCloudFact = myServiceUnderTest.retrieveFact(EXISTING_VARIA);

          assertThat(springCloudFact, is(new SpringCloudFact(EXISTING_VARIA, "OK")));

      }

      @Test

      public void serviceShouldReturnNothing() {

          RestTemplate restTemplate = mock(RestTemplate.class);

          when(restTemplate.getForEntity(FACT_URL, SpringCloudFactResponse.class, NON_EXISTING_HTTP_PARAMS))

                  .thenReturn(ERROR_RESPONSE);

          SpringCloudService myServiceUnderTest = new SpringCloudService(restTemplate);

          SpringCloudFact springCloudFact = myServiceUnderTest.retrieveFact(NON_EXISTING_VARIA);

          assertThat(springCloudFact, is(nullValue()));

      }

      @Test(expected = ResourceAccessException.class)

      public void serviceShouldPropagateException() {

          RestTemplate restTemplate = mock(RestTemplate.class);

          when(restTemplate.getForEntity(FACT_URL, SpringCloudFactResponse.class, BAD_HTTP_PARAMS))

                  .thenThrow(new ResourceAccessException("I/O error"));

          SpringCloudService myServiceUnderTest = new SpringCloudService(restTemplate);

          myServiceUnderTest.retrieveFact(BAD_VARIA);

      }

  }

从上面可以看出,单测代码不仅对RestTemplate有了强依赖,且有很多重复的地方。

二、优化方案

经过阅读mockito的说明文档,发现mockito除了常用的thenReturn、thenThrow方法,还有一个thenAnswer方法。这个方法通过接收参数,实现一个通用的接口,而这个通用接口基本上可以返回任何想要的东西。

相比于常用的thenReturn、thenThrow方法(只返回固定的值),thenAnswer可以计算返回值,也就是说T answer(InvocationOnMockinvocation)throwsThrowable和[Java](javascript:;) 8新特性中的函数式接口 java.util.function.Function的功能基本相同 ,唯一不同可能也就是 throws了吧。有了个这个方法,我们就可以进一步优化代码了:


  public class SpringCloudServiceStepOneTest {

      private static final Long EXISTING_VARIA = 1L;

      private static final Map GOOD_HTTP_PARAMS = Collections.singletonMap("id", EXISTING_VARIA);

      private static final Long NON_EXISTING_VARIA = 15123123L;

      private static final Map NON_EXISTING_HTTP_PARAMS = Collections.singletonMap("id", NON_EXISTING_VARIA);

      private static final Long BAD_VARIA = 99999999L;

      private static final Map BAD_HTTP_PARAMS = Collections.singletonMap("id", BAD_VARIA);

      private static final ResponseEntity ERROR_RESPONSE =

              new ResponseEntity<>(new SpringCloudFactResponse("NoSuchQuoteException", "No quote with id=15123123."), HttpStatus.OK);

      private static final ResponseEntity ITEM_RESPONSE =

              new ResponseEntity<>(new SpringCloudFactResponse("success", new SpringCloudFact(1L, "OK")), HttpStatus.OK);

      @Test

      public void serviceShouldReturnFact() {

          RestTemplate restTemplate = restEndpointShouldAnswer(GOOD_HTTP_PARAMS, (invocation) -> ITEM_RESPONSE);

          SpringCloudService myServiceUnderTest = new SpringCloudService(restTemplate);

          SpringCloudFact springCloudFact = myServiceUnderTest.retrieveFact(EXISTING_VARIA);

          assertThat(springCloudFact, is(new SpringCloudFact(EXISTING_VARIA, "OK")));

      }

      @Test

      public void serviceShouldReturnNothing() {

          RestTemplate restTemplate = restEndpointShouldAnswer(NON_EXISTING_HTTP_PARAMS, (invocation -> ERROR_RESPONSE));

          SpringCloudService myServiceUnderTest = new SpringCloudService(restTemplate);

          SpringCloudFact springCloudFact = myServiceUnderTest.retrieveFact(NON_EXISTING_VARIA);

          assertThat(springCloudFact, is(nullValue()));

      }

      @Test(expected = ResourceAccessException.class)

      public void serviceShouldPropagateException() {

          RestTemplate restTemplate = restEndpointShouldAnswer(BAD_HTTP_PARAMS, (invocation -> {throw new ResourceAccessException("I/O error");}));

          SpringCloudService myServiceUnderTest = new SpringCloudService(restTemplate);

          myServiceUnderTest.retrieveFact(BAD_VARIA);

      }

      private RestTemplate restEndpointShouldAnswer(Map httpParams, Answer> response){

          RestTemplate restTemplate = mock(RestTemplate.class);

          when(restTemplate.getForEntity(FACT_URL, SpringCloudFactResponse.class, httpParams)).thenAnswer(response);

          return restTemplate;

      }

  }

优化点:

可以直接看到HTTP参数与响应的对照关系

可以绕过处理逻辑,不需要URL,HTTP方法这些依赖

可以将RestTemplate的mock提取成一个通用的方法,单测代码依赖度更低

 问题:

代码不优美,每个单测中都有RestTemplate

三、进一步优化

通过 @Before解决上述问题:


  public class SpringCloudServiceStepTwoTest {

      private static final Long EXISTING_VARIA = 1L;

      private static final Map GOOD_HTTP_PARAMS = Collections.singletonMap("id", EXISTING_VARIA);

      private static final Long NON_EXISTING_VARIA = 15123123L;

      private static final Map NON_EXISTING_HTTP_PARAMS = Collections.singletonMap("id", NON_EXISTING_VARIA);

      private static final Long BAD_VARIA = 99999999L;

      private static final Map BAD_HTTP_PARAMS = Collections.singletonMap("id", BAD_VARIA);

      private static final ResponseEntity ERROR_RESPONSE =

              new ResponseEntity<>(new SpringCloudFactResponse("NoSuchQuoteException", "No quote with id=15123123."), HttpStatus.OK);

      private static final ResponseEntity ITEM_RESPONSE =

              new ResponseEntity<>(new SpringCloudFactResponse("success", new SpringCloudFact(1L, "OK")), HttpStatus.OK);

      private RestTemplate restTemplate;

      private SpringCloudService myServiceUnderTest;

      @Before

      public void setUp(){

          restTemplate = mock(RestTemplate.class);

          myServiceUnderTest = new SpringCloudService(restTemplate);

      }

      @Test

      public void serviceShouldReturnFact() {

          restEndpointShouldAnswer(GOOD_HTTP_PARAMS, (invocation) -> ITEM_RESPONSE);

          SpringCloudFact springCloudFact = myServiceUnderTest.retrieveFact(EXISTING_VARIA);

          assertThat(springCloudFact, is(new SpringCloudFact(EXISTING_VARIA, "OK")));

      }

      @Test

      public void serviceShouldReturnNothing() {

          restEndpointShouldAnswer(NON_EXISTING_HTTP_PARAMS, (invocation -> ERROR_RESPONSE));

          SpringCloudFact springCloudFact = myServiceUnderTest.retrieveFact(NON_EXISTING_VARIA);

          assertThat(springCloudFact, is(nullValue()));

      }

      @Test(expected = ResourceAccessException.class)

      public void serviceShouldPropagateException() {

          restEndpointShouldAnswer(BAD_HTTP_PARAMS, (invocation -> {throw new ResourceAccessException("I/O error");}));

          myServiceUnderTest.retrieveFact(BAD_VARIA);

      }

      private void restEndpointShouldAnswer(Map httpParams, Answer> response){

          when(restTemplate.getForEntity(FACT_URL, SpringCloudFactResponse.class, httpParams)).thenAnswer(response);

      }

  }

四、总结

thenAnswer+lambda的方法虽然不是通用所有的case,但还是能解决大部分的单测依赖度高与代码重复较高的问题,根据说明文档,还有restEndpointShouldAnswer这个方法应该可以更进一步简化代码。无论采用什么方法,核心的思想就是AIR(Automatic, Independent, Repeatable)原则,保证了这个原则,才是高质量的单测代码。

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