Write Spring Boot integration tests with Testcontainers (JUnit 4 & 5)

Recently, I was looking for a solution to write integration tests for my Spring Boot-based application which was using PostgreSQL. I had the following requirements for this task:

The integration tests should use the same database as in production (referring to the Twelve-Factor App I wanted to keep my environment during the tests as similar as possible to the production environment)
The tests should not need any pre-setup before running (e.g. like manually setting up a test database)
The tests should use my Flyway DDL scripts and create-drop (spring.jpa.hibernate.ddl-auto) shouldn’t be activated for my tests
Good integration with the excellent Spring tests ecosystem

For this task, I found the awesome project: Test containers. The project describes itself as the following:

“Testcontainers is a Java library that supports JUnit tests, providing lightweight, throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.”

With this blog post, we’ll use Testcontainers to write integration tests with JUnit using a real database (meaning not mocked or in-memory) for a Spring Boot application.

UPDATE: Time flies and a lot was introduced since I published this blog post. Therefore I added integration test examples for different combinations of JUnit 4 & 5 and Spring Boot versions.

Setup Testcontainers in Spring Boot project

For using this dependency you need to have Docker on your local machine/on your build server (Jenkins etc.).

With Testcontainers you can use a @ClassRule or @Rule on each of your integration tests and define the Docker image for your test (valid for JUnit 4.12).

For MySQL and PostgreSQL and there are already built-in solutions but you are free to use an image of your choice like the following:


<span>// generic container for self-defined Docker images</span>
<span>@ClassRule</span>
<span>public</span> <span>static</span> <span>GenericContainer</span> <span>redis</span> <span>=</span> <span>new</span> <span>GenericContainer</span><span>(</span><span>"redis:3.0.6"</span><span>).</span><span>withExposedPorts</span><span>(</span><span>6379</span><span>);</span>
<span>// built-in containers</span>
<span>@ClassRule</span>
<span>public</span> <span>static</span> <span>PostgreSQLContainer</span> <span>postgreSQLContainer</span> <span>=</span> <span>new</span> <span>PostgreSQLContainer</span><span>().</span><span>withPassword</span><span>(</span><span>"inmemory"</span><span>)</span>
            <span>.</span><span>withUsername</span><span>(</span><span>"inmemory"</span><span>);</span>
<span>// generic container for self-defined Docker images</span>
<span>@ClassRule</span>
<span>public</span> <span>static</span> <span>GenericContainer</span> <span>redis</span> <span>=</span> <span>new</span> <span>GenericContainer</span><span>(</span><span>"redis:3.0.6"</span><span>).</span><span>withExposedPorts</span><span>(</span><span>6379</span><span>);</span>

<span>// built-in containers</span>
<span>@ClassRule</span>
<span>public</span> <span>static</span> <span>PostgreSQLContainer</span> <span>postgreSQLContainer</span> <span>=</span> <span>new</span> <span>PostgreSQLContainer</span><span>().</span><span>withPassword</span><span>(</span><span>"inmemory"</span><span>)</span>
            <span>.</span><span>withUsername</span><span>(</span><span>"inmemory"</span><span>);</span>
// generic container for self-defined Docker images
@ClassRule
public static GenericContainer redis = new GenericContainer("redis:3.0.6").withExposedPorts(6379);

// built-in containers
@ClassRule
public static PostgreSQLContainer postgreSQLContainer = new PostgreSQLContainer().withPassword("inmemory")
            .withUsername("inmemory");