Wiremock returning wrong content-type for Spring Cloud Contract stub runner - spring

Question

I'm trying out Spring-Cloud-Contract for the first time. I'm trying to have my client auto-discover the contract stubs, but even though my contract specifies a content-type of 'application/json' on the response, what I get from WireMock has a content-type of 'application/octet'. What am I doing wrong?
I have a simple method in my service which returns a model like this from a /status endpoint:
{
"name": string,
"status": string
}
My contract looks like this:
import org.springframework.cloud.contract.spec.Contract
Contract.make {
request {
method('GET')
headers {
contentType(applicationJson())
}
url("/status")
}
response {
status OK()
body(
name: "Demo",
status: "RUNNING"
)
headers {
contentType(applicationJson())
}
}
}
In my client, I have a class which uses a Spring RestTemplate to query this endpoint:
#Component
public class StatusClient {
private final RestTemplate restTemplate;
public StatusClient(RestTemplate restTemplate) {
this.restTemplate = restTemplate;
}
public Status getStatus() {
return this.restTemplate
.exchange("http://localhost:8080/status", HttpMethod.GET, null, Status.class)
.getBody();
}
}
#Data
class Status implements Serializable {
private String name;
private String status;
}
My unit test uses #AutoConfigureStubRunner to pull the latest version of the contract from the local repository and assert against the response from the contract (eg name = Demo, status = RUNNING).
#RunWith(SpringRunner.class)
#SpringBootTest
#AutoConfigureStubRunner(ids = {"com.example:contract-demo:+:8080"}, stubsMode = StubRunnerProperties.StubsMode.LOCAL)
public class StatusClientTests {
#Autowired
private StatusClient client;
#Test
public void testThatStatusReturnsSuccessfully() {
Status result = this.client.getStatus();
assertEquals("Demo", result.getName());
assertEquals("RUNNING", result.getStatus());
}
}
When I run the test, WireMock reports the contract it received as expected:
2018-05-31 11:36:49.919 INFO 14212 --- [tp1255723887-26] WireMock : Request received:
127.0.0.1 - GET /status
User-Agent: [Java/1.8.0_161]
Connection: [keep-alive]
Host: [localhost:8080]
Accept: [application/json, application/*+json]
Matched response definition:
{
"status" : 200,
"body" : "{\"name\":\"Demo\",\"status\":\"RUNNING\"}",
"headers" : {
"contentType" : "application/json"
},
"transformers" : [ "response-template" ]
}
Response:
HTTP/1.1 200
contentType: [application/json]
But when the RestTemplate tries to deserialize it, it throws an exception because the response content type is actually "application/octet" once it hits the methods to extract the data:
org.springframework.web.client.RestClientException: Could not extract response: no suitable HttpMessageConverter found for response type [class com.example.contractclientdemo.Status] and content type [application/octet-stream]
at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:119)
at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:991)
at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:974)
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:725)
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:680)
at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:600)
at com.example.contractclientdemo.StatusClient.getStatus(StatusClient.java:18)
I'm using Finchley.RC2 for the Spring cloud version, and spring-cloud-starter-contract-stub-runner is my only test dependency other than spring-boot-starter-test.
I know WireMock is returning the wrong content type because I debugged deep into the HttpMessageConverterExtractor class in Spring and that's what the getContentType method returned when queried.
Why is WireMock returning the wrong content type, though it reports the correct one in the log? And how can I get it to properly return an application/json so I can deserialize my simple message?

Answer 1

I had the exact same problem than you. I solved it by adding
headers {
header 'Content-Type': 'application/json;charset=UTF-8'
}
to the response.
You seem to have in your response, although written in another way, but that did solve the problem in my case. So this have something to do with it.
Before making the change, curl showed no Content-Type response header :
curl -v -H "Accept: application/json" localhost:6565/products/ABC
* Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 6565 (#0)
GET /products/ABC HTTP/1.1
Host: localhost:6565
User-Agent: curl/7.58.0
Accept:application/json
HTTP/1.1 200 OK
Transfer-Encoding: chunked
Server: Jetty(9.2.z-SNAPSHOT)
Connection #0 to host localhost left intact
{
"price": {
"currencyCode": "EUR",
"value": "100.50"
},
"name": "Fake product"
}
After doing the change, curl returned this and the RestTemplate managed to deserialize it.
HTTP/1.1 200 OK
Content-Type: application/json;charset=UTF-8
Transfer-Encoding: chunked
Server: Jetty(9.2.z-SNAPSHOT)
Here's my working contract :
import org.springframework.cloud.contract.spec.Contract
Contract.make {
description "should return product information"
request{
method GET()
url("/products/ABC")
}
response {
status 200
headers {
header 'Content-Type': 'application/json;charset=UTF-8'
}
body([
name: 'Fake product',
price:[
currencyCode: 'EUR',
value: 100.50
]
])
}
}
Hope this helps

Answer 2

I think you should file it as an issue in WireMock. Also you're not setting the application / json content type header in the request explicit. Maybe that's a problem? Also shouldn't it be content-type as the header name in the response stub?