JUnit is one of the most popular unit testing frameworks used with Java to create repeatable tests. With JUnit, each test is written as a separate method inside a Java class. IntelliJ IDEA provides an option to run these test cases from within the IDE.
In case you have a module that communicates with a MySQL database, you can unit test the module by providing it access to a MySQL server running inside a Testcontainer. You can also configure this MySQL database instance with your desired username, password, and database name (in MySQL server) using the API provided by the Testcontainers framework.