Unit-Tests can be helpful when working with Java as they can give you a semi REPL-like environment (especially if your IDE integrates well with JUnit). I find

Unit-Tests can be helpful when working with Java as they can give you a semi REPL-like environment (especially if your IDE integrates well with JUnit). I find both Integration and Acceptance Tests could potentially hide many bad internal designs (tight coupling, etc). I also find that not many places can speed up their full integration/acceptance tests suites; suddenly build becomes way too painful, be it local dev build or CI-triggered-through-commit builds. Note: My experience with super-slow integration tests choking build is with a large JavaScript project with 100 developers (at least). I implemented integration-tests for a Java-heavy based project before but limited only to test the database component of the project (e.g.: Repository, JPQL, JPA), the ability to test business logics that are tightly coupled with ORM quickly in isolated manner is a blessing. I guess YMMV.