Search⌘ K
AI Features
Home
Courses
Build E-Commerce Apps with Reactive Programming in Spring Boot

Crafting a Test Case

Explore how to implement test-first development for asynchronous messaging in Spring Boot. Understand how to test a web controller that converts synchronous requests into asynchronous RabbitMQ messages, verify message handling with MongoDB, and use JUnit 5 with Testcontainers to manage RabbitMQ instances during testing.

We'll cover the following...

With everything in place, it’s time to determine what our system will do. We’re talking about an asynchronous message solution. A simple thing to implement would be receiving a request for a new Item object at a web controller and forwarding the information as a message through RabbitMQ. A service would be elsewhere, listening for messages. That service could then write the new Item to MongoDB.

This is a very simple concept we can use over and over. We can also adapt it to our needs. It’s easy to swap out the web controller with something else. Perhaps a message was also transmitted via RabbitMQ. Or, perhaps someone directly invoking the API.

Defining a test class

Let’s return to the initial problem. Namely, a web controller that turns synchronous web requests into asynchronous messages. This time, we’ll choose a test-first approach.

Spring Boot Test, JUnit 5, and Testcontainers put this at our fingertips:

Java
@SpringBootTest //1
@AutoConfigureWebTestClient //2
@Testcontainers //3
@ContextConfiguration //4
public class RabbitTest {
    @Container static RabbitMQContainer container = new RabbitMQContainer(); //5
    @Autowired WebTestClient webTestClient; //6
    @Autowired ItemRepository repository; //7
    @DynamicPropertySource //8
    static void configure(DynamicPropertyRegistry registry) {
        registry.add("spring.rabbitmq.host", container::getContainerIpAddress);
        registry.add("spring.rabbitmq.port", container::getAmqpPort);
    }
    ...
}
Beginning with a test

Here’s a breakdown of the code above:

  1. In line 1, ...