RSpec evidence with progress bar

Just found that 'rspec' takes multiple options to specify formats like I do in the following snippet.

'-f Fuubar' to show a progress bar.
I do test all specs of thousands in a project I'm currently working on. So, better have a progress bar.

'-f doc' to generate sentences according to specs.
I use methods 'let', 'subject', 'shared_examples_for' make output of 'rspec' self-explanatory.