Add option to shuffle test files.

[floere]

This is an idea that I'd like to put forth:
Add "shuffle" option. This adds a -u/--shuffle option (default is "do not shuffle", as it is currently).

Reason:
I really do like the new -a option. However, I do believe - ymmv - that tests should be run in random order to detect setup/code loading issues.

Currently, I do have to use something akin to FileList["spec/#{dir}/*_spec.rb"].shuffle.join ' ' to make this happen, which negates the benefits of -a.

Always shuffling, adding a shuffle option (e.g. -u), or always shuffling on -a would be my wish-order.

I'd like to put this idea up for discussion. Thanks for considering it :)

[alloy]

👍

This is something that comes up most often across platforms where the default FS order might be different, e.g. local OS X remote (TravisCI) Linux.

One thing I’d like to see added is printing the full command that you can copy-paste to easily reproduce the results locally.

[floere]

I completely forgot to add that at least in case of shuffling, the file order used should be printed (thanks @alloy for the reminder). But perhaps let's discuss this PR first.

[alloy]

I think it’s an essential part of this UX feature and important to take into consideration when thinking about the usefulness of it.

[floere]

Travis is failing because this is 1.9.3+ code only.

[mmzoo]

Is there a chance this can get merged in or does Bacon support Ruby 1.8?