如何在 WebClient 单元测试中使用 MockWebServer 模拟错误响应

Question

我正在为使用 WebClient 调用 REST 端点的方法编写单元测试。使用 MockWebServer，我能够覆盖成功响应的代码，但是我找不到任何方法来模拟错误响应，以便与错误处理有关的相关代码也包含在单元测试中。

来源class:

@Service
@Slf4j
public class EmployeeService {

   private final WebClient webClient;
   private final PaymentServiceConfiguration paymentServiceConfiguration;
   
   public EmployeeService(WebClient webClient, PaymentServiceConfiguration paymentServiceConfiguration){
      this.webClient = webClient;
      this.paymentServiceConfiguration= paymentServiceConfiguration;

   }

   public Mono<PaymentDataResponse> getPaymentInfo(PaymentDataRequest paymentDataRequest){
      return webClient
             .post()
             .uri(paymentServiceConfiguration.getBaseUri() + "/payment")
             .body(Mono.just(paymentDataRequest, PaymentDataRequest.class)
             .retrieve()
             .onStatus(HttpStatus::isError, this.handleErrorResponse)
             .bodyToMono(PaymentDataResponse.class)
             .doOnError((throwable)-> {
                 log.error("Exception in getPaymentInfo method. Message {}", throwable.getMessage());
                 throw(Exceptions.propagate(throwable));
             });

   }

   private Mono<? extends Throwable> handleErrorResponse(ClientResponse clientResponse){
      Mono<String> errorMessage = clientResponse.bodyToMono(String.class);
      return errorMessage.flatMap((message) -> {
         log.error("Error response code is: {}, and the message is: {} ", clientResponse.rawStatusCode(), message);
         return Mono.error(new RuntimeException(message));
      });
   }

}

测试Class:

@RunWith(MockitoJunitRunner.class)
public class EmployeeServiceTest {
   private MockWebServer server;
   private EmployeeService employeeService;
   private PaymentServiceConfiguration paymentServiceConfiguration;
   private String paymentServiceUri;

   @Before
   public void setUp() throws IOException{
     paymentServiceConfiguration = mock(PaymentServiceConfiguration.class);
     paymentServiceUri = "/paymentdomain.com";
     employeeService = new EmployeeService(WebClient.create(), paymentServiceConfiguration);
     server = new MockWebServer();
     
     server.start();
   }

  @Test
  public testPaymentInfo() throws IOException, InterruptedException {
     when(paymentServiceConfiguration.getBaseUri()).thenReturn(server.url(paymentServiceUri).url.toString());

     String result = "{\"paymentId\": 101, "\paymentType\": \"online\"}";

     server.enque(
         new MockResponse.setResponseCode(200)
                 .setHeader("content-type", "application/json")
                 .setBody(result);
     );
     
     StepVerifier.create(employeeService.getPaymentInfo(new PaymentDataRequest())
          .expectNext(new ObjectMapper.readValue(result, PaymentDataResponse.class))
          .expectComplete()
          .verify();
     
     RecordRequest request = server.takeRequest();
     Assert.assertEquals("POST", request.getMethod());
     Assert.assertEquals("/paymentdomain.com/payment", request.getPath());
  }

  @After
  public void tearDown() throws IOException {
     server.shutdown();
  }
   
}

以上测试涵盖了代码的快乐路径，并适当标记了代码覆盖率。我怎样才能在这里模拟错误，以便它可以覆盖源代码中的以下几行 class 代码（关于错误场景）

// .onStatus(HttpStatus::isError, this.handleErrorResponse)

// .doOnError((throwable)-> { ......

Answer 1

您需要提供错误状态 4xx 或 5xxx。例如，

server.enqueue(
        new MockResponse().setResponseCode(500)
                .setHeader("content-type", "application/json")
                .setBody("{}");
);

StepVerifier.create(employeeService.getPaymentInfo(new PaymentDataRequest())
        .expectError()
        .verify();

ps

我建议查看 WireMock which provides a very good API for testing web clients matchig . You could test posittive and negative scanarios including timeouts, retry logic using Scenarios or even simulate timeouts using Delays。

如何在 WebClient 单元测试中使用 MockWebServer 模拟错误响应

How to mock error response using MockWebServer in WebClient unit tests

junit

mockito

spring-webflux

spring-webclient