Before: call ale#test#SetDirectory('/testplugin/test') After: call ale#test#RestoreDirectory() Execute(Detect root of Python project with .flake8 correctly): call ale#test#SetFilename('python-test-files/python-package-project/package-name/module.py') AssertEqual \ ale#path#Simplify(g:dir . '/python-test-files/python-package-project'), \ ale#python#FindProjectRoot(bufnr(''))