There are some really fantastic testing resources in the Ruby community. The talk that most influenced my approach to building unit tests (even though I write Go these days) was one of Jim Weirich’s: https://youtu.be/983zk0eqYLY

I’ve found that his zero-knowledge approach gives me a suite of tests that have high signal when they fail.

Sandi Metz has also spoken extensively on testing, and I particularly like her advice on using mocks in tests appropriately. This talk of hers on the subject comes to mind: https://youtu.be/URSWYvyc42M