Java test covered sample project?

In company I work, we DO NOT write tests (no unit/integration tests). But I understand this is very necessary to know how to test. But again I dont have any examples, practice, mentors to review my code.

Can you please suggest some test covered sample project or good tutorial which covers all needed things to understand testing(unit, some integration) in your opinion(based on best testing practices in your organization). Actually I know how to test in theory, so I'm looking for examples.

Now I'm on standard Java project type and frameworks: DAO-Service layers, ORM, Spring.

Very appreciate your help.