Before: call ale#assert#SetUpFixerTest('python', 'black') silent cd .. silent cd command_callback let g:dir = getcwd() let b:bin_dir = has('win32') ? 'Scripts' : 'bin' After: call ale#assert#TearDownFixerTest() unlet! g:dir unlet! b:bin_dir Execute(The black callback should return the correct default values): silent execute 'file ' . fnameescape(g:dir . '/python_paths/with_virtualenv/subdir/foo/bar.py') AssertEqual \ { \ 'cwd': '%s:h', \ 'command': ale#Escape(ale#path#Simplify(g:dir . '/python_paths/with_virtualenv/env/' . b:bin_dir . '/black')) . ' -'}, \ ale#fixers#black#Fix(bufnr('')) Execute(The black callback should include options): let g:ale_python_black_options = '--some-option' let g:ale_python_black_change_directory = 0 silent execute 'file ' . fnameescape(g:dir . '/python_paths/with_virtualenv/subdir/foo/bar.py') AssertEqual \ {'command': ale#Escape(ale#path#Simplify(g:dir . '/python_paths/with_virtualenv/env/' . b:bin_dir . '/black')) . ' --some-option -' }, \ ale#fixers#black#Fix(bufnr('')) Execute(The black callback should include --pyi for .pyi files): let g:ale_python_black_change_directory = 0 silent execute 'file ' . fnameescape(g:dir . '/python_paths/with_virtualenv/subdir/foo/bar.pyi') AssertEqual \ {'command': ale#Escape(ale#path#Simplify(g:dir . '/python_paths/with_virtualenv/env/' . b:bin_dir . '/black')) . ' --pyi -' }, \ ale#fixers#black#Fix(bufnr('')) Execute(Pipenv is detected when python_black_auto_pipenv is set): let g:ale_python_black_auto_pipenv = 1 let g:ale_python_black_change_directory = 0 call ale#test#SetFilename('../python_fixtures/pipenv/whatever.py') AssertEqual \ {'command': ale#Escape('pipenv') . ' run black -'}, \ ale#fixers#black#Fix(bufnr(''))