Mocha v4.0.0 is nearing release. With this new version also comes the obligatory breaking changes, and I'll enumerate them below. UPDATE (April 18, 2018): Mocha v4 was released on October 2, 2017. Mocha Will No Longer Support Node.js Pre-v4.0.0 There are several reasons for this: These versions of Node.js are no longer maintained and (some) have known security vulnerabilities which will not receiv