thoughtbot/shoulda-matchers — pull request #298 by ivanvc (2013-05-17 18:28:01+00:00)
Title: Fix validate_uniqueness_of.scoped_to issue when scoped field is already taken

Re-implement how to get previous value in order to test
validate_uniquenes_of matcher, after the scope changes. This way, new
value should not be taken by a previous record. Fixes #207.