In using IntelliJ Ultimate 2017.1 (on MacOS) and the tests for "Programming Assignment: Recursion" worked no problem.
Downloaded recfun.zip, unzipped. Move unzipped structure to "My Projects" folder
In IntelliJ closed existing projects. From the dialog box choose:
Import Project
Navigate to root of project folder and chose "recfun"
Make sure "Import from project from external model" is checked and highlight 'SBT'. Click next.
Choose SDK from dropdown 1.8 and Project Format ".idea ....."
Should load fine.
Changed the "stubbing" ??? in main.scala to some value say 1.
Then open one (of the three) unit tests say "PascalSuite" and right click from within the source, choose "Run PascalSuite" and see the results.

https://www.coursera.org/learn/progfun1/discussions/weeks/1/threads/GlW7gCvAEeaatw7rZVB3fw