While poking around in IRB and looking at the autocompletion results, I found some functions that I didn't recognize and decided to take a look at what they do. I found some pretty interesting stuff. It looks like some of these commands have been added recently to come up to par with pry, and others have been kicking around for a while and just flying under the radar.

If you're in the default testing environment your rails cache is ActiveSupport::Cache::NullStore which will always succeed but it doesn't actually store or return anything. There's an almost completely undocumented method called with_local_cache on NullStore that lets you run a block with a MemoryStore instead of a NullStore for the duration of the block. This happens because it prepends the ActiveSupport::Cache::Strategy::LocalCache class. This lets you test one or two things that require caching without enabling it on all tests and slowing everything down.