Spring Test - Integration Testing with TestRestTemplate

Spring Test provides have few options to test our controllers. So in this post let’s take a look to how to test controllers with TestRestTemplate. These tests are run as an integration tests. In that kind of tests are no difference what are our application doing on production(ignoring other system components proxy servers, load-balancing etc.). These kind of tests are suitable to test any HTTP related problems. You also have more argument when some of your client/friend come to your table and blame you that your endpoints are not working.

Introduction to TestRestTemplate

TestRestTemplate helps us to send http request in our integration tests. To do that need all application context should be running. Also Spring run a local server in a random port @LocalServerPort. So just need to create the request in integration tests and send it like a clients of your servers. TestRestTemplate have all necessary methods to send the request to server with a convenient way similar to RestTemplate.

Configuration

Just need to add testCompile("org.springframework.boot:spring-boot-starter-test") to our gradle file. Because this is an integration test so Spring will run all application context. Because of that @SpringBootTest annotation should be added at the beginning of test class.

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class HttpRequestTest {
	private static final Long productId = 1L;
	@LocalServerPort private int port;

	@Autowired private TestRestTemplate restTemplate;

	@Test
	public void returnProductWithHttpStatusCode200_ifProductIsExist() {
		//To be provided
	}
}

How to write a test with TestRestTemplate

Sample current application have two endpoints. GET /v1/product/{productId} to get the product data with productId and POST /v1/product create the product.

        @Test
	public void returnProductWithHttpStatusCode200_ifProductIsExist() {
		String productName = "Product-" + productId;
		IProductPort.ProductRequest productRequest =
				new IProductPort.ProductRequest().setId(productId).setName(productName);

		restTemplate.postForObject("http://localhost:" + port + "/v1/product", productRequest, String.class);

		assertThat(restTemplate.getForObject("http://localhost:" + port + "/v1/product/" + productId, String.class))
				.contains(productId.toString())
				.contains(productName);
	}

So first sent a POST request to create a product. Then sent a GET request to get the product data and check that actual and expected responses are same or not.

Notes

Because @SpringBootTest needs all application contexts, these tests spend more time than unit tests. It can cause some delay to your build pipeline, they should be configure wisely. Also it is a good practice to configure it with a different profile.

Result

So Spring starts the server and make the tests as much as close to production environment.

You can find the all project on Github

References

https://spring.io/guides/gs/testing-web/

Happy coding :)