Database connection tester is asserted by the unit test and by GET and POST #314

What is wrong

DatabaseConnectionTesterServiceTest and DatabaseConnectionControllerTest use the same drivers and the same URLs, including the malformed jdb:h2:mem:testdb. A tester bug fails the unit test and both HTTP methods. GET-by-id and POST are different routes, and the unit test locks the exception type.

What to do

Decide that one HTTP entry point is enough before deleting either controller method. Do not delete the unit test.