Before: Save g:ale_typescript_tslint_executable Save g:ale_typescript_tslint_config_path let g:ale_typescript_tslint_executable = 'xxxinvalid' let g:ale_typescript_tslint_config_path = 'tslint.json' call ale#test#SetDirectory('/testplugin/test/fixers') silent cd .. silent cd command_callback let g:dir = getcwd() After: Restore call ale#test#RestoreDirectory() Execute(The tslint callback should return the correct default values): call ale#test#SetFilename('../prettier-test-files/testfile.ts') AssertEqual \ { \ 'read_temporary_file': 1, \ 'command': ale#Escape(g:ale_typescript_tslint_executable) \ . ' -c ' . ale#Escape('tslint.json') \ . ' --fix %t', \ }, \ ale#fixers#tslint#Fix(bufnr('')) Execute(The tslint callback should include custom tslint config option): let g:ale_typescript_tslint_config_path = '.tslintrc' call ale#test#SetFilename('../prettier-test-files/testfile.ts') AssertEqual \ { \ 'read_temporary_file': 1, \ 'command': ale#Escape(g:ale_typescript_tslint_executable) \ . ' -c ' . ale#Escape(g:ale_typescript_tslint_config_path) \ . ' --fix %t', \ }, \ ale#fixers#tslint#Fix(bufnr(''))