$ git reset --hard
$ git clean -dxf
えいっ!!
$ rbenv local 2.7.2
$ bundle install --path=vendor/bundle
$ yarn
$ bundle exec rake test
/home/zunda/.rbenv/versions/2.7.2/bin/ruby -w -I"lib:test" -I"/home/zunda/src/github.com/zunda/webpacker/vendor/bundle/ruby/2.7.0/gems/rake-13.0.1/lib" "/home/zunda/src/github.com/zunda/webpacker/vendor/bundle/ruby/2.7.0/gems/rake-13.0.1/lib/rake/rake_test_loader.rb" "test/command_test.rb" "test/compiler_test.rb" "test/configuration_test.rb" "test/dev_server_runner_test.rb" "test/dev_server_test.rb" "test/engine_rake_tasks_test.rb" "test/env_test.rb" "test/helper_test.rb" "test/manifest_test.rb" "test/rake_tasks_test.rb" "test/webpack_runner_test.rb" "test/webpacker_test.rb"
うしうし
$ bundle exec irb -Ilib:test -r test_helper
irb(main):001:0>
うしうしもーもー