How to Reduce Test Interference in Minitest

I was working on the test suite for active_record_doctor when I run into an interesting problem. Many active_record_doctor tasks are applied at the model-level which means they iterate over all Active Record models and process them one-by-one.I had to replace the dummy test app (that the Rails generator had created) with test cases based on dynamically-defined Active Record models. This improved test cohesion and readability but unexpectedly resulted in unpredictable test failures.