Setup Test Database

In our previous lesson, we configured PostgreSQL as our production database.

Setting up a separate test database will allow us to run tests without requiring PostgreSQL to be running.

This separation of test and production databases is crucial for reliable continuous integration and development workflows.

Understanding Test Database Requirements

Spring Boot provides excellent support for using different databases in different environments.

The H2 database is an excellent choice for testing because it runs in memory and doesn't require external setup.

This approach ensures our tests are fast, reliable, and truly isolated from the production environment.

Observing the Current Problem

If we try running tests with PostgreSQL stopped, we'll see failures:

docker-compose down
./mvnw test

The test failure occurs because our application tries to connect to PostgreSQL, which isn't available:

Connection to localhost:5432 refused

Configuring the Test Database

Create a new file src/test/resources/application.properties with the following configuration:

# Test Database Configuration
spring.datasource.url=jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE
spring.datasource.username=sa
spring.datasource.password=
spring.datasource.driver-class-name=org.h2.Driver

# JPA Configuration
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.jpa.hibernate.ddl-auto=create-drop
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true

Understanding the Configuration

The jdbc:h2:mem:testdb URL specifies an in-memory database that's created fresh for each test run.

The create-drop setting ensures our database schema is created before tests and dropped afterward, providing a clean slate for each test.

Spring Boot automatically prioritizes test-specific properties files during test execution.

Verifying the Setup

Now we can run our tests without PostgreSQL running:

./mvnw test

The tests should now pass, using the H2 database instead of PostgreSQL.

Summary

H2 provides a lightweight, in-memory database perfect for testing
Separate application.properties files enable environment-specific configurations
The create-drop setting ensures a clean test database for each test run
Spring Boot automatically selects the appropriate database configuration based on the runtime environment
Independent test databases enable reliable continuous integration pipelines