thoughtbot/shoulda-matchers — pull request #71 by vpereira (2012-03-14 09:31:08+00:00)
Title: refering ticket #70

It's more like a proof of concept but it works.

now you can do something like:

ensure_inclusion_of_matcher(:attr).in_array [true,false]

we could implement as well the ensure_exclusion_of_matcher(:attr).in_array []