Thinking Aloud about Testing a Module

I have a module that handles getting a DBI object connecting to MySQL databases. With some work, it could be made to talk to others, but since I don't really have any Oracle or PostgreSQL databases to connect to, it hasn't been worth it.

I have another module that handles calling the first module, managing credentials so they don't show up in code, getting and holding the DBI object and doing the actual calls to the database. This way, I can set a variable saying this DB is named 'foo' and say "I want an arrayref containing the result of this query" without dealing with all the nooks and crannies of DBI.

I now have a module that uses that second module to do work. Get information from the database, throw it into an object and kick it out to be converted to JSON later. And I want to write tests for it. But I have thought and continue to think that having a test that queries a database in a way that requires a dynamic resource to be static is stupid.

Is the way to test it to feed in a "this is a test" flag somewhere, stick a bunch of canned output into the functions to output if the flag, because what I should be testing here is that the module dumps things the right way, right?