Before: Save g:ale_puppet_puppetlint_executable Save g:ale_puppet_puppetlint_options " Use an invalid global executable, so we don't match it. let g:ale_puppet_puppetlint_executable = 'xxxinvalid' let g:ale_puppet_puppetlint_options = '--invalid' 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 puppetlint callback should return the correct default values): silent execute 'file ' . fnameescape(g:dir . '/puppet_paths/dummy.pp') AssertEqual \ {'read_temporary_file': 1, \ 'command': ale#Escape(g:ale_puppet_puppetlint_executable) \ . ' ' . g:ale_puppet_puppetlint_options \ . ' --fix %t' }, \ ale#fixers#puppetlint#Fix(bufnr(''))