Before: call ale#assert#SetUpLinterTest('python', 'pyls') let b:bin_dir = has('win32') ? 'Scripts' : 'bin' After: unlet! b:bin_dir unlet! b:executable call ale#assert#TearDownLinterTest() Execute(The pyls command callback should return default string): AssertLinter 'pyls', ale#Escape('pyls') Execute(The pyls executable should be configurable): let g:ale_python_pyls_executable = '~/.local/bin/pyls' AssertLinter '~/.local/bin/pyls' , ale#Escape('~/.local/bin/pyls') Execute(The pyls executable should be run from the virtualenv path): call ale#test#SetFilename('python_paths/with_virtualenv/subdir/foo/bar.py') let b:executable = ale#path#Simplify( \ g:dir . '/python_paths/with_virtualenv/env/' . b:bin_dir . '/pyls' \) AssertEqual ale#Escape(b:executable), \ ale_linters#python#pyls#GetCommand(bufnr('')) Execute(You should be able to override the pyls virtualenv lookup): call ale#test#SetFilename('python_paths/with_virtualenv/subdir/foo/bar.py') let g:ale_python_pyls_use_global = 1 AssertLinter 'pyls', ale#Escape('pyls') Execute(Setting executable to 'pipenv' appends 'run pyls'): let g:ale_python_pyls_executable = 'path/to/pipenv' AssertLinter 'path/to/pipenv', ale#Escape('path/to/pipenv') . ' run pyls' Execute(Pipenv is detected when python_pyls_auto_pipenv is set): let g:ale_python_pyls_auto_pipenv = 1 call ale#test#SetFilename('/testplugin/test/python_fixtures/pipenv/whatever.py') AssertLinter 'pipenv', \ ale#Escape('pipenv') . ' run pyls'