Replace H2 with a real database for testing

In this guide, you will learn how to:

• Understand the drawbacks of using H2 in-memory databases for testing
• Replace H2 with a real PostgreSQL database using the Testcontainers special JDBC URL
• Use the Testcontainers JUnit 5 extension for more control over the container
• Test both Spring Data JPA and JdbcTemplate-based repositories

Prerequisites

• Java 17+
• Maven or Gradle
• A Docker environment supported by Testcontainers

Note

If you're new to Testcontainers, visit the Testcontainers overview to learn more about Testcontainers and the benefits of using it.

Modules

1. The H2 problem

   Understand why using H2 in-memory databases for testing gives false confidence.

2. JDBC URL approach

   Use the Testcontainers special JDBC URL to swap H2 for a real PostgreSQL database.

3. JUnit 5 extension

   Use the Testcontainers JUnit 5 extension for more control over the PostgreSQL container.