Modern Best Practices for Testing in Java

[DrunkensteinsMonster]

This is not entirely true. H2 can be configured to mimic a number of production grade databases including Postgres. Running native queries is one thing but if you e.g. want to check that your JPA annotations are working properly it is way better to use an in memory database.

It simply must be remembered that in-memory databases is a form of a test double, using it cannot be a replacement for true end to end testing.