Install all needed gems to run the tests:
appraisal install
The gems are installed into the global gem list.
The Gemfiles in the gemfiles folder are also re-generated.
For all supported Rails/ActiveRecord versions:
rake
Or for specific version one:
appraisal rails_4.2 rake
Or for one particular test file
appraisal rails_4.2 ruby test/active_record_test.rb
Or down to one test case
appraisal rails_4.2 ruby test/active_record_test.rb -n "/permit replacing value/"