I have just downloaded this tutorial code onto my Mac (I wrote it on a Windows machine), cleared the contents of the context file and repopulated it with my Google Credentials (leaving both tokens blank). The first time I ran it I got an issue with Google not permitting me to run it because of a lack of a Product Name. This must be a new requirement since I wrote the tutorial. However, there was no need to edit the tutorial code, I simply went to the Google API Console and amended my credentials to be up to date (they were previously about 2 years old). I then ran it and it worked first time.
So, I can only assume that your credentials must be wrong somewhere. You cannot use the credentials you will find in the file since they are rubbish for demonstration only. Below are the values you need for your first file. After the job has been run successfully for the first time, they will be populated completely. See that my tokens are missing. Also see where I have values in curly brackets, these need to be specific to your user. If you followed my tutorial in how I configured my Google API, the redirect_uri and scope should match below.
client_secret;{YOUR SECRET}
redirect_uri;http%3A%2F%2Flocalhost
refresh_token;
scope;https://www.googleapis.com/auth/drive
context_file;{YOUR CONTEXT FILE PATH}
access_token;
client_id;{YOUR CLIENT ID}
If this doesn't work I am afraid I am not entirely sure what it is without looking at it myself. As I said, I downloaded the code and added it to my machine to test it and apart from playing with a few credential changes, it worked as expected.
