Before: Save g:ale_python_pylint_executable Save g:ale_python_pylint_options Save g:ale_python_pylint_use_global unlet! g:ale_python_pylint_executable unlet! g:ale_python_pylint_options unlet! g:ale_python_pylint_use_global runtime ale_linters/python/pylint.vim call ale#test#SetDirectory('/testplugin/test/command_callback') let b:bin_dir = has('win32') ? 'Scripts' : 'bin' let b:command_tail = ' --output-format text --msg-template="{path}:{line}:{column}: {msg_id} ({symbol}) {msg}" --reports n %s' After: Restore call ale#test#RestoreDirectory() call ale#linter#Reset() unlet! b:bin_dir unlet! b:executable Execute(The pylint callbacks should return the correct default values): AssertEqual \ 'pylint', \ ale_linters#python#pylint#GetExecutable(bufnr('')) AssertEqual \ ale#Escape('pylint') . ' ' . b:command_tail, \ ale_linters#python#pylint#GetCommand(bufnr('')) Execute(The pylint executable should be configurable, and escaped properly): let g:ale_python_pylint_executable = 'executable with spaces' AssertEqual \ 'executable with spaces', \ ale_linters#python#pylint#GetExecutable(bufnr('')) AssertEqual \ ale#Escape('executable with spaces') . ' ' . b:command_tail, \ ale_linters#python#pylint#GetCommand(bufnr('')) Execute(The pylint command callback should let you set options): let g:ale_python_pylint_options = '--some-option' AssertEqual \ ale#Escape('pylint') . ' --some-option' . b:command_tail, \ ale_linters#python#pylint#GetCommand(bufnr('')) Execute(The pylint callbacks shouldn't detect virtualenv directories where they don't exist): silent execute 'file ' . fnameescape(g:dir . '/python_paths/no_virtualenv/subdir/foo/bar.py') AssertEqual \ 'pylint', \ ale_linters#python#pylint#GetExecutable(bufnr('')) AssertEqual \ ale#Escape('pylint') . ' ' . b:command_tail, \ ale_linters#python#pylint#GetCommand(bufnr('')) Execute(The pylint callbacks should detect virtualenv directories): silent execute 'file ' . fnameescape(g:dir . '/python_paths/with_virtualenv/subdir/foo/bar.py') let b:executable = ale#path#Winify( \ g:dir . '/python_paths/with_virtualenv/env/' . b:bin_dir . '/pylint' \) AssertEqual \ b:executable, \ ale_linters#python#pylint#GetExecutable(bufnr('')) AssertEqual \ ale#Escape(b:executable) . ' ' . b:command_tail, \ ale_linters#python#pylint#GetCommand(bufnr('')) Execute(You should able able to use the global pylint instead): silent execute 'file ' . fnameescape(g:dir . '/python_paths/with_virtualenv/subdir/foo/bar.py') let g:ale_python_pylint_use_global = 1 AssertEqual \ 'pylint', \ ale_linters#python#pylint#GetExecutable(bufnr('')) AssertEqual \ ale#Escape('pylint') . ' ' . b:command_tail, \ ale_linters#python#pylint#GetCommand(bufnr(''))