Mock external server during integration testing with Spring

Question

After playing a bit with various scenarios, here is the one way how can one achieve what was asked with minimal interventions to the main code

Refactor your controller to use a parameter for thirdparty server address:

@RestController
public class HelloController {
    @Value("${api_host}")
    private String apiHost;

    @RequestMapping("/hello_to_facebook")
    public String hello_to_facebook() {
        // Ask facebook about something
        HttpGet httpget = new HttpGet(buildURI("http", this.apiHost, "/oauth/access_token"));
        String response = httpClient.execute(httpget).getEntity().toString();
        // .. Do something with a response
        return response + "_PROCESSED";
    }
}

‘api_host’ equals to ‘graph.facebook.com’ in application.properties in the src/main/resources

Create a new controller in the src/test/java folder that mocks the thirdparty server.
Override ‘api_host’ for testing to ‘localhost’.

Here is the code for steps 2 and 3 in one file for brevity:

@RestController
class FacebookMockController {
    @RequestMapping("/oauth/access_token")
    public String oauthToken() {
        return "TEST_TOKEN";
    }
}

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = Application.class)
@WebAppConfiguration
@IntegrationTest({"api_host=localhost",})
public class TestHelloControllerIT {        
    @Test
    public void getHelloToFacebook() throws Exception {
        String url = new URL("http://localhost:8080/hello_to_facebook").toString();
        RestTemplate template = new TestRestTemplate();
        ResponseEntity<String> response = template.getForEntity(url, String.class);
        assertThat(response.getBody(), equalTo("TEST_TOKEN_PROCESSED"));

        // Assert that facebook mock got called:
        // for example add flag to mock, get the mock bean, check the flag
    }
}

Is there a nicer way to do this? All feedback is appreciated!

P.S. Here are some complications I encountered putting this answer into more realistic app:

Eclipse mixes test and main configuration into classpath so you might screw up your main configuration by test classes and parameters: https://issuetracker.springsource.com/browse/STS-3882 Use gradle bootRun to avoid it

You have to open access to your mocked links in the security config if you have spring security set up. To append to a security config instead of messing with a main configuration config:

@Configuration
@Order(1)
class TestWebSecurityConfig extends WebSecurityConfig {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests()
                .antMatchers("/oauth/access_token").permitAll();
        super.configure(http);
    }
}

It is not straightforward to hit https links in integration tests. I end up using TestRestTemplate with custom request factory and configured SSLConnectionSocketFactory.

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