thoughtbot/shoulda-matchers — pull request #182 by drapergeek (2012-11-02 18:54:15+00:00)
Title: Add allow_nil option to the validate uniquness matcher

This should fix issue #96.

I'm open to suggestion better ways to handle this. One thing in particular is that I'm not thrilled about having to check for an existing nil in the valid_attribute method. I dont' like the idea of mixing those concerns so any ideas on how to pull that out would be great.