TestRestTemplate for full integration in Spring Boot - Mini Project: Build & Apply

TestRestTemplate for Full Integration Testing in Spring Boot

📖 Scenario: You are building a simple Spring Boot application that manages a list of books. You want to test the full integration of your REST API endpoints to make sure they work correctly from end to end.

🎯 Goal: Create a Spring Boot integration test using TestRestTemplate to verify the REST API endpoints for adding and retrieving books.

📋 What You'll Learn

Create a simple Book class with id and title fields

Create a REST controller with endpoints to add and get books

Configure TestRestTemplate in the test class

Write integration tests that use TestRestTemplate to call the REST endpoints

💡 Why This Matters

🌍 Real World

Integration tests ensure your REST API works correctly when all parts run together, just like real users would use it.

💼 Career

Spring Boot developers often write integration tests with TestRestTemplate to catch bugs early and deliver reliable APIs.

1

Create the Book class

Create a Java record called Book with two fields: Long id and String title.

Spring Boot

// Your code here

Need a hint?

A record is a simple way to create immutable data classes in Java 17+. Use the syntax public record Book(Long id, String title) {}.

2

Create the REST controller

Create a Spring REST controller class called BookController with a List<Book> books field initialized as an empty ArrayList. Add two endpoints: a @PostMapping("/books") method addBook that takes a @RequestBody Book book and adds it to books, and a @GetMapping("/books") method getBooks that returns the list books.

Spring Boot

public record Book(Long id, String title) {}

// Your code here

Need a hint?

Use @RestController to create the controller. Initialize books as new ArrayList<>(). Use @PostMapping and @GetMapping annotations for the methods.

3

Configure TestRestTemplate in the test class

Create a test class called BookControllerIntegrationTest annotated with @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT). Inject a TestRestTemplate field called restTemplate using @Autowired.

Spring Boot

import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.web.client.TestRestTemplate;

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class BookControllerIntegrationTest {

    // Your code here

}

Need a hint?

Use @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT) to start the server on a random port. Inject TestRestTemplate with @Autowired.

4

Write integration tests using TestRestTemplate

In BookControllerIntegrationTest, add a test method testAddAndGetBooks annotated with @Test. Use restTemplate.postForEntity("/books", new Book(1L, "Spring Boot Guide"), Void.class) to add a book. Then use restTemplate.getForObject("/books", Book[].class) to get the books array. Assert that the array length is 1 and the first book's title is "Spring Boot Guide".

Spring Boot

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class BookControllerIntegrationTest {

    @Autowired
    private TestRestTemplate restTemplate;

    // Add testAddAndGetBooks method here

}

Need a hint?

Use restTemplate.postForEntity to send a POST request and restTemplate.getForObject to send a GET request. Use JUnit assertions to check the results.