Before: Save g:ale_ruby_rufo_executable " Use an invalid global executable, so we don't match it. let g:ale_ruby_rufo_executable = 'xxxinvalid' call ale#test#SetDirectory('/testplugin/test/fixers') silent cd .. silent cd command_callback let g:dir = getcwd() After: Restore call ale#test#RestoreDirectory() Execute(The rufo command should contain `bundle exec` when executable is `bundle`): let g:ale_ruby_rufo_executable = 'bundle' call ale#test#SetFilename('ruby_paths/dummy.rb') AssertEqual \ ale#Escape('bundle') . ' exec rufo %t', \ ale#fixers#rufo#GetCommand(bufnr('')) Execute(The rufo callback should return the correct default values): call ale#test#SetFilename('ruby_paths/dummy.rb') AssertEqual \ { \ 'read_temporary_file': 1, \ 'command': ale#Escape('xxxinvalid') . ' %t' \ }, \ ale#fixers#rufo#Fix(bufnr(''))