I want to mock a server before bean creation in spring boot integration test - spring-boot

Question

I am writing Integration tests in spring-boot.
One of my beans is using UrlResource("http://localhost:8081/test") for its creation.
I want to create a mock server, which will serve the above url with a mock response.
But I want this mock server to be created before any bean is initialized, as the mock server should be available to serve requests before the bean is initialized.
I have tried using the MockRestServiceServer in the #TestConfiguration
Following is the pseudo code which is failing:
#RunWith(SpringRunner.class)
#SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class TestApiGatewayApplicationTests {
#Autowired
private TestRestTemplate restTemplate;
#Test
public void contextLoads() {
}
#TestConfiguration
class TestConfig {
#Bean
public RestTemplateBuilder restTemplateBuilder() {
RestTemplate restTemplate = new RestTemplate();
MockRestServiceServer mockServer = MockRestServiceServer.createServer(restTemplate);
String mockKeyResponse = "{\"a\":\"abcd\"}";
mockServer.expect(requestTo("http://localhost:8081/test"))
.andExpect(method(HttpMethod.GET))
.andRespond(withSuccess(mockKeyResponse, MediaType.TEXT_PLAIN));
RestTemplateBuilder builder = mock(RestTemplateBuilder.class);
when(builder.build()).thenReturn(restTemplate);
return builder;
}
}
}
Following is the sample code for creation of bean which is to be tested.
#Configuration
public class BeanConfig {
#Bean
public SampleBean sampleBean(){
Resource resource = new UrlResource("");
// Some operation using resource and create the sampleBean bean
return sampleBean;
}
}
Using the above approach I am getting
" java.net.ConnectException: Connection refused (Connection refused)"
error as it is not able to access the http://localhost:8081/test endpoint.

Answer 1

Use #InjectMocks.
Reference : documentation and Explaination with example.

Answer 2

I have solved this issue by creating a MockServiceServer in the testConfiguration.
Sample code is as follows.
#TestConfiguration
static class TestConfig {
#Bean
public RestTemplateBuilder restTemplateBuilder() {
RestTemplate restTemplate = new RestTemplate();
MockRestServiceServer mockServer = MockRestServiceServer.createServer(restTemplate);
String mockKeyResponse = "{\"a\":\"abcd\"}";
mockServer.expect(requestTo("http://localhost:8081/test"))
.andExpect(method(HttpMethod.GET))
.andRespond(withSuccess(mockKeyResponse, MediaType.TEXT_PLAIN));
RestTemplateBuilder builder = mock(RestTemplateBuilder.class);
when(builder.build()).thenReturn(restTemplate);
return builder;
}
}
Then in the class BeanConfig where I needed to use this I have autowired using constructor injection, so that RestTemplate will be created before bean of BeanConfig class is created.
Following is how I did it.
#Configuration
public class BeanConfig {
private RestTemplate restTemplate;
public BeanConfig(RestTemplate restTemplate) {
this.restTemplate = restTemplate;
}
#Bean
public SampleBean sampleBean(){
Resource resource = new UrlResource("");
// Some operation using resource and create the sampleBean bean
return sampleBean;
}
}