The default backtrace handling for rspec is ... okay. It would be nice if you could find the source of exceptions during test runs without having to see *all* the backtraces, right? That's what this thing is for: it compacts backtraces, skims out things that should be ignored (and respects ignore_patterns), then trims filenames and contracts repetition into a legible format.
Gemfile gem 'rspec-cleverbacktrace', '~> 0.1'
install gem install rspec-cleverbacktrace