ignoring R project & history files.
Ignoring R project & related files.
This second prototype for Coursera/swirl interaction has the same functionality as the first but implements it as a custom test which resides in the lesson directory. It run s in vanilla swirl, requiring no special code in the swirl package.

This prototype also demonstrates how a custom test may override a built-in test of the same name.
Merge branch 'coursera2'