gem install cleanser

curl https://rubinjam.herokuapp.com/pack/cleanser > cleanser && chmod +x cleanser

# whole test folder
cleanser folder folder/failing_test.rb

Running: bundle exec ruby -r./folder/failing_test.rb -e ''
Status: Success
Running: bundle exec ruby -r./folder/a_test.rb -r./folder/failing_test.rb -r./folder/b_test.rb -e ''
Status: Failure
Running: bundle exec ruby -r./folder/failing_test.rb -r./folder/b_test.rb -e ''
Status: Failure
Fails when folder/b_test.rb.rb, folder/failing_test.rb are run together

# individual files (copied from CI failure)
cleanser other_test.rb failing_test.rb yetanother_test.rb failing_test.rb --seed 12345

# rspec
cleanser other_spec.rb failing_spec.rb yetanother_spec.rb failing_spec.rb --rspec --seed 12345

# files from copy-pasted output
cleanser '"other_test.rb","failing_test.rb","yetanother_test.rb"' failing_test.rb