thoughtbot/appraisal — pull request #23 by radar (2012-02-15 05:22:50+00:00)
Title: Support ENV['BUNDLE_GEMFILE'] variable

This is because this could *potentially* be set to something other than Gemfile.

For example, in Spree, we have a dummy application that lives at spec/dummy inside each engine component. Each engine component has a Gemfile at the root of its directory. The dummy applications contain no Gemfile, and so their config/boot.rb sets the ENV['BUNDLE_GEMFILE'] path to go back up to the root's Gemfile.

Appraisal doesn't acknowledge this environment variable, but should.