Good point but to make this work all `DB<Adapter>Test` classes should extend one, common base class e.g. `DBAdapterTestAbstract`.

Currently `DBMSSQLTest`, `DBPostgresTest` extends `PHPUnit_Framework_TestCase`
and `DBAdapterTest`, `BookstoreTestBase`, `DBOracleTest` extends `BookstoreTestBase`.

I think I can make `DBAdapterTestAbstract` to extend `BookstoreTestBase` and then force all `DB<Adapter>Test` classes to extend `DBAdapterTestAbstract` with defined `abstract public function testQuotingIdentifiers()`. This shouldn't brake anything.

This is what you thought or maybe I misunderstood you?