Testing a Feign Client - spring-cloud-feign

Question

I've written a feign client and I would like to test that it works using a unit test.
For my case, integration tests is not the right approach for the current development stage.
The feign client is null, I receive a NullPointerException while running the test.
How can I autowire it?
Feign client
package com.myapp.clients;
import com.myapp.model.StatusResponse;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
#FeignClient(name="myClient", url="${feign.clients.my.url}")
public interface myClient {
#RequestMapping(method= RequestMethod.GET, value="/v1/users/{userId}")
StatusResponse getStatus(
#RequestHeader(value = "Auth", required = true) String authorizationHeader,
#RequestHeader(value = "my_tid", required = true) String tid,
#PathVariable("userId") String userId);
}
Tests:
package com.myapp.clients;
import com.intuit.secfraudshared.step.broker.model.StatusResponse;
import org.junit.Assert;
import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;
public class MyClientTest {
#Autowired
MyClient myClient;
#Test
public void testmyClient_status200() {
StatusResponse myResponse = myClient.getStatus("", "tidTestSample", "4626745161770145");
Assert.assertNotNull(iusResponse);
}
}
How can autowire MyClient?

Answer 1

The method that has worked for me so far while trying to test Feign Clients is stubbing the response via wiremock. You would need to add dependency for wiremock.
testImplementation 'org.springframework.cloud:spring-cloud-contract-wiremock'
Then you would need to annotate as
#RunWith(SpringRunner.class)
#SpringBootTest(properties = "feign.clients.my.url=http://localhost:${wiremock.server.port}")
#AutoConfigureWireMock(port = 0)
And then stub using wiremock.
stubFor(post(urlPathMatching("/v1/users/([a-zA-Z0-9-]*)")).willReturn(aResponse().withStatus(200).withHeader("content-type", "application/json").withBody("{\"code\":200,\"status\":\"success\"})));
where ([a-zA-Z0-9-]*) is regex for {userId} assuming it is alphanumeric.
And then, of course, assert.
StatusResponse myResponse = myClient.getStatus("", "tidTestSample", "4626745161770145");
Assert.assertNotNull(myResponse);