Function `prepare_exec_for_file` has a side effect where a path is added to `sys.path` list. This commit enhances an exisiting test case for `prepare_exec_for_file` by testing the side effect of the function and adding necessary comments.
change string to docstring
* Forward port the CLI tests from Flask-CLI. * Make sure the parameter passed to the CLI's AppGroup is the app's name, not the app itself.