A test database is a more-or-less exact copy of your live/production database environment. I often refer to this as a “sandbox” because the test database is a place where you and your staff can go to play, just like a sandbox.
The three primary uses of a test database are for testing, training, and documentation. All three of these are activities your association should already be engaged in. And all three of them should NOT occur in your live/production database. So by definition, you should have a sandbox environment.
Many associations I’ve worked with did not have these environments available to them (before I started working with them!) either because they felt it was an unnecessary expense of because their vendor didn’t offer one.
But this is a must-have. So if you don’t have one, talk to your vendor now, and get one.