Python Testing with pytest, Second Edition: File not Found Error (page 43)

I ran this command after installing the sample application:

$ cards add do something --owner Brian

And got a file not found error:

FileNotFoundError: [Errno 2] No such file or directory: ‘/Users/tslcw/cards_db/.cards_db.json’

perhaps this is because I am using a folder in drop box as my work directory? Also, it would be nice to have an option to create the cards db in the cards_proj folder or the cards directory in the venv directory.