Before: call ale#assert#SetUpLinterTest('python', 'mypy') call ale#test#SetFilename('test.py') let b:bin_dir = has('win32') ? 'Scripts' : 'bin' After: unlet! b:bin_dir unlet! b:executable call ale#assert#TearDownLinterTest() Execute(The mypy callbacks should return the correct default values): AssertLinter 'mypy', \ ale#path#CdString(g:dir) . ale#Escape('mypy') \ . ' --show-column-numbers' \ . ' --shadow-file %s %t %s' Execute(The mypy executable should be configurable, and escaped properly): let g:ale_python_mypy_executable = 'executable with spaces' AssertLinter 'executable with spaces', \ ale#path#CdString(g:dir) . ale#Escape('executable with spaces') \ . ' --show-column-numbers' \ . ' --shadow-file %s %t %s' Execute(The mypy command callback should let you set options): let g:ale_python_mypy_options = '--some-option' AssertLinter 'mypy', \ ale#path#CdString(g:dir) . ale#Escape('mypy') \ . ' --some-option' \ . ' --show-column-numbers' \ . ' --shadow-file %s %t %s' Execute(The mypy command should switch directories to the detected project root): silent execute 'file ' . fnameescape(g:dir . '/python_paths/no_virtualenv/subdir/foo/bar.py') AssertLinter 'mypy', \ ale#path#CdString(ale#path#Simplify(g:dir . '/python_paths/no_virtualenv/subdir')) \ . ale#Escape('mypy') \ . ' --show-column-numbers' \ . ' --shadow-file %s %t %s' Execute(The mypy callbacks should detect virtualenv directories and switch to the project root): silent execute 'file ' . fnameescape(g:dir . '/python_paths/with_virtualenv/subdir/foo/bar.py') let b:executable = ale#path#Simplify(g:dir . '/python_paths/with_virtualenv/env/' . b:bin_dir . '/mypy') AssertLinter b:executable, \ ale#path#CdString(ale#path#Simplify(g:dir . '/python_paths/with_virtualenv/subdir')) \ . ale#Escape(b:executable) \ . ' --show-column-numbers' \ . ' --shadow-file %s %t %s' Execute(The mypy callbacks should cd to directory containing mypy.ini if found): silent execute 'file ' . fnameescape(g:dir . '/python_paths/with_mypy_ini_and_pytest_ini/tests/testsubfolder/my_tests.py') AssertLinter 'mypy', \ ale#path#CdString(ale#path#Simplify(g:dir . '/python_paths/with_mypy_ini_and_pytest_ini')) \ . ale#Escape('mypy') \ . ' --show-column-numbers' \ . ' --shadow-file %s %t %s' Execute(You should able able to use the global mypy instead): silent execute 'file ' . fnameescape(g:dir . '/python_paths/with_virtualenv/subdir/foo/bar.py') let g:ale_python_mypy_use_global = 1 AssertLinter 'mypy', \ ale#path#CdString(ale#path#Simplify(g:dir . '/python_paths/with_virtualenv/subdir')) \ . ale#Escape('mypy') \ . ' --show-column-numbers' \ . ' --shadow-file %s %t %s' Execute(Setting executable to 'pipenv' appends 'run mypy'): let g:ale_python_mypy_executable = 'path/to/pipenv' AssertLinter 'path/to/pipenv', \ ale#path#CdString(expand('#' . bufnr('') . ':p:h')) \ . ale#Escape('path/to/pipenv') . ' run mypy' \ . ' --show-column-numbers --shadow-file %s %t %s' Execute(Pipenv is detected when python_mypy_auto_pipenv is set): let g:ale_python_mypy_auto_pipenv = 1 call ale#test#SetFilename('../python_fixtures/pipenv/whatever.py') AssertLinter 'pipenv', \ ale#path#CdString(expand('#' . bufnr('') . ':p:h')) \ . ale#Escape('pipenv') . ' run mypy --show-column-numbers --shadow-file %s %t %s'