Have each .t file exercise a specific part of your functionality. It's ok to have a lot of test files if your distro has a lot of use cases. For example,
DBM::Deep is up to 29 test files and I'll be adding probably 3-4 more in the next month.
It's also ok to have only 2-3 testcases in a .t file. Remember - each .t file is run in a separate process, meaning that each one is in its own sandbox. There's a lot of safety in that - don't feel obligated to condense the number of .t files you have.
My criteria for good software:
- Does it work?
- Can someone else come in, make a change, and be reasonably certain no bugs were introduced?