Because of the complexity of setting up a true, database-free mock, and the concern that this mock object actually performs as expected in all cases, what I would instead do is to set up a small, separate, test database which has the same structure as the original but only a smattering of (fake, or sanitized) data. Completely different passwords, etc. Then, point your test-scripts to that database, making damn sure(!) that they are in an environment which cannot access production by any means whatever. Consider taking a dump of that database's "initial, pristine" contents so that you can quickly restore it during the test cycle.