Redmine

I'm not aware of any plugins, but you can integrate our test management tool TestRail (http://www.gurock.com/testrail/) with Redmine. Hope this helps.

I think this is not the best place to ask question, and I understand that you want to make a feature request.

In this forum topic there's a discussion about a plugin for Tests Case Develpoment/Execution.

Tested mostly on redmine 2.3.3 https://github.com/cforce/redmine_impasse/network