Are concise body arrow functions allowed in Mocha callback functions?

before(() => path = ‘./message.txt’); // Would not pass the check

afterEach(() => {
fs.unlinkSync(path);
});

I was stuck doing the Mocha hook’s lesson because I had written a before hook with a concise body arrow function as shown above. I had to rewrite it using brackets before the lesson check passed my work.

Are they not allowed in Mocha?

I’m not Mocha familiar but a quick search had this in one of the results:

Passing arrow functions to Mocha is discouraged.
Mocha examples should not use arrow functions · Issue #318 · meteor/guide · GitHub