This is absolutely the correct answer. Testing infra should be ephemeral and mostly stateless. Prior to docker you had to figure out ways to mock the database

This is absolutely the correct answer. Testing infra should be ephemeral and mostly stateless. Prior to docker you had to figure out ways to mock the database or use something to approximate it with a lite weight DB like H2 or SqlLite. With docker you can build out the test image with default usernames/passwords/etc... Then as your install gets more complicated with stored procedures and the like you can add them to your test database and update local testing tooling and CI/CD to use that. The massive benefit here is that you're using the exact same code to power your tests as you use to power your production systems. This eliminates issues that are the caused by differences between prod & test environments and anyone who's debugged those issues know how long they can take because it can take a really long time to figure out that is where the issue lies.