Running MySQL in-Memory for Efficient JUnit Testing

When writing test cases for services interacting with a MySQL database, setting up a testing environment can be time-consuming and introduces potential dialect-specific issues. Fortunately, there is a convenient solution: running MySQL in-memory for JUnit tests.

Utilizing MariaDB4j

The most recommended approach for in-memory MySQL in JUnit tests is MariaDB4j. This dependency offers seamless compatibility with MySQL and requires minimal setup:

DB database = DB.newEmbeddedDB(3306);
database.start();
Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/test", "root", "");

Including a startup script:

database.source("path/to/resource.sql");

Additional Notes

It's crucial to understand that while MariaDB4j simulates an in-memory environment, it operates within the system's temporary folder. This means it functions embeddededly, eliminating the need for external installation. However, it's not a genuine in-memory solution, as it still relies on files, potentially violating the principles of unit testing that prohibit external dependencies.