Integration test with mongodb using testcontainers

Introduction

Test containers provide a way to run tests in an isolated environment, which means that the tests are not affected by the state of the host system or any external dependencies. This makes it easier to write and run tests that are deterministic and repeatable. Test containers can start up quickly, which means that you can run tests more frequently and get faster feedback on the results.They provide a convenient way to manage the external dependencies required for your tests. You can easily spin up and tear down the necessary resources, such as databases or message brokers, as needed.

Setting Up the Spring Boot Application with test-container dependency

Add the below dependency in the pom.xml

<dependencies>
 <!-- Test Containers Start -->
        <dependency>
            <groupId>org.testcontainers</groupId>
            <artifactId>junit-jupiter</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.testcontainers</groupId>
            <artifactId>mongodb</artifactId>
            <version>1.17.6</version>
            <scope>test</scope>
        </dependency>
<!-- Test Containers End -->
</dependencies>


    <dependencyManagement>
        <dependencies>
         <dependency>
                <groupId>org.testcontainers</groupId>
                <artifactId>testcontainers-bom</artifactId>
                <version>1.17.3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
   </dependencyManagement>
        

}

Spring Boot Application

package com.thecodeshelf.learningtestcontainers;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.DynamicPropertyRegistry;
import org.springframework.test.context.DynamicPropertySource;
import org.testcontainers.containers.MongoDBContainer;
import org.testcontainers.junit.jupiter.Container;
import org.testcontainers.junit.jupiter.Testcontainers;
import org.testcontainers.utility.DockerImageName;

import java.util.UUID;

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.NONE)
@Testcontainers
class LearningTestcontainersApplicationTests {

    @Autowired
    private CartRepository cartRepository;

    @Container
    private static MongoDBContainer container = new MongoDBContainer(DockerImageName.parse("mongo:4.0.10"));

    @DynamicPropertySource
    public static void overrideProps(DynamicPropertyRegistry registry){
        registry.add("spring.data.mongodb.uri",container::getReplicaSetUrl);
    }

    @Test
    void validateCartItemsCount() {
        CartCollection cart = new CartCollection();
        cart.setCartId(UUID.randomUUID().toString());
        cartRepository.save(cart);
        System.out.println("Cart has been saved to the Test Container");
        int totalCartCount = (int) cartRepository.count();
        System.out.println("Cart Count from Mongo Test Container is : " + totalCartCount);
    }

}

@DynamicPropertySource : This annotation helps with overriding the values from the property file at athe runtime.

Overall, test containers are a valuable tool for testing Java applications that depend on external resources, helping to improve the reliability and consistency of your tests.

Code is available here : GitHub Project

Happy Coding !