Getting "reactor.netty.http.client.PrematureCloseException: Connection prematurely closed BEFORE response" while mocking a third part API - spring

Question

My Spring boot API is consuming a third part API using WebClient
DemoAPIController
#RestController
public class DemoAPIController
{
#Autowired
DemoService demoService;
#GetMapping("/mytest")
public Mono<UserType> getUserType()
{
return demoService.getUserType();
}
}
DemoService.java
#Component
public class DemoService
{
#Value("${base.url}")
private String baseUrl;
public Mono<UserType> getUserType()
{
System.out.println("baseUrl:" + baseUrl);
WebClient webClient = WebClient.builder().baseUrl(baseUrl)
.defaultHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
.defaultHeader("apikey", "test").build();
Mono<UserType> testResult = webClient.get()
.uri("/valic/valic-security-data-api/v1/utility/users/ID873366777/usertype?appName=EAO").retrieve()
.bodyToMono(UserType.class);
testResult.subscribe(value -> System.out.println(value.getUserType()));
return testResult;
}
}
I have mocked the third part API using MockWebServer. When I try to test the API using mockMvc.perform(...). My assertions are working as expected. But while shutting down the MockWebServer, I am getting the following exception
2019-11-29 16:02:43.308 INFO 13048 --- [127.0.0.1:53970] okhttp3.mockwebserver.MockWebServer : MockWebServer[443] received request: GET /valic/valic-security-data-api/v1/utility/users/ID873366777/usertype?appName=EAO HTTP/1.1 and responded: HTTP/1.1 200 OK
2019-11-29 16:03:18.362 INFO 13048 --- [ckWebServer 443] okhttp3.mockwebserver.MockWebServer : MockWebServer[443] done accepting connections: socket closed
2019-11-29 16:03:18.385 WARN 13048 --- [ctor-http-nio-1] r.netty.http.client.HttpClientConnect : [id: 0x186c45c1, L:0.0.0.0/0.0.0.0:53970 ! R:localhost/127.0.0.1:443] The connection observed an error
reactor.netty.http.client.PrematureCloseException: Connection prematurely closed BEFORE response
2019-11-29 16:03:18.389 INFO 13048 --- [127.0.0.1:53970] okhttp3.mockwebserver.MockWebServer : MockWebServer[443] connection from /127.0.0.1 failed: java.net.SocketException: Socket closed
2019-11-29 16:03:20.509 INFO 13048 --- [extShutdownHook] o.s.s.concurrent.ThreadPoolTaskExecutor : Shutting down ExecutorService 'applicationTaskExecutor'
My Test case
#ExtendWith(SpringExtension.class)
#WebAppConfiguration()
#ContextConfiguration(classes = WebclientApplication.class)
#SpringBootTest
public class EmployeeServiceMockWebServerTest
{
public static MockWebServer mockWebServer;
private ObjectMapper MAPPER = new ObjectMapper();
public MockMvc mockMvc;
public MediaType contentType = new MediaType(MediaType.APPLICATION_JSON.getType(),
MediaType.APPLICATION_JSON.getSubtype(), Charset.forName("utf8"));
public MediaType contentTypeURLEncoded = new MediaType(MediaType.APPLICATION_FORM_URLENCODED.getType(),
MediaType.APPLICATION_FORM_URLENCODED.getSubtype(), Charset.forName("utf8"));
#Autowired
private WebApplicationContext webApplicationContext;
#BeforeAll
static void setUp() throws IOException
{
mockWebServer = new MockWebServer();
mockWebServer.start(443);
}
#AfterAll
static void tearDown() throws IOException
{
mockWebServer.shutdown();
}
#BeforeEach
void initialize()
{
this.mockMvc = MockMvcBuilders.webAppContextSetup(webApplicationContext).build();
System.out.println("Hostname:" + mockWebServer.getHostName());
System.out.println("Port:" + mockWebServer.getPort());
}
#Test
void getEmployeeById() throws Exception
{
UserType userType = new UserType();
userType.setUserType("PAR-Mock");
ServiceMessage serviceMessage = new ServiceMessage();
serviceMessage.setCode("200");
serviceMessage.setType("OK");
serviceMessage.setDescription("From Mock");
userType.setServiceMessage(serviceMessage);
mockWebServer.enqueue(
new MockResponse().setBody(MAPPER.writeValueAsString(userType)).addHeader("Content-Type", "application/json"));
mockMvc.perform(get("/mytest").contentType(contentType)).andExpect(status().isOk());
RecordedRequest recordedRequest = mockWebServer.takeRequest();
assertEquals("GET", recordedRequest.getMethod());
assertEquals("/logic/logic-security-data-api/v1/utility/users/ID873366777/usertype?appName=EAO",
recordedRequest.getPath());
}
}
I tried all the solution mentioned in other start overflow posts but still I am getting the same error. Any help is appreciated.

Answer 1

I fixed the issue by commenting the below line.
testResult.subscribe(value -> System.out.println(value.getUserType()));
I created WebClient object using the below code to get additional logging
WebClient webClient = WebClient.builder()
.clientConnector(new ReactorClientHttpConnector(HttpClient.newConnection().compress(true).wiretap(true)))
.baseUrl(baseUrl).defaultHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
.defaultHeader("apikey", "somekey").build();
I was able to see two requests.Then after commenting, everything worked as expected.