I just wanted to let you know that there are some changes in the
latest Mocha release that might break integration with
ActiveSupport::TestCase et al.
The main change is that Mocha no longer loads any testing frameworks
itself. Instead, when Mocha is loaded, it looks to see what testing
frameworks have *already* been loaded, and monkey-patches them
Previously, Mocha used to attempt to load testing frameworks itself,
before then monkey-patching them.
This change was in response to a bug report  from someone wanting
to use Mocha without Rails, Test::Unit or MiniTest. I think this is a
The new version of Mocha also avoids loading RubyGems. This Gist 
explains why it's a bad idea for a library to explicitly load
More details of the Mocha release can be found here .
I apologise if these changes cause problems with
ActiveSupport::TestCase, but I'm very willing to help fix any
problems. I'm going to have a look at the code in
ActiveSupport::TestCase now and see whether I can suggest any changes
or improvements. I've created a Lighthouse ticket  to keep track of
any work in this area.