Closure Compiler Externs for Function with static fields

Question

What is the correct type for a constructor function that also has properties on the function object with Google's closure compiler?

Here's a runnable first attempt on the Closure compiler debugger .

Application Code

const Mocha = /** @type {!MochaJS} */ (require('mocha'));

const mochaInstance = new Mocha();
const Suite = Mocha.Suite;

Closure Externs

/** @constructor */
const MochaJS = function() {};

/** @type {!MochaJS.Suite} */
MochaJS.prototype.Suite;

/** @record */
MochaJS.Suite = function() {};

Answer 1

The difficulty comes because Closure-compiler doesn't handle external module definitions well. Also, dont' confuse the constructor/namespace with an instance. They are different.

Application

// A constructor type for Mocha
const Mocha = /** @type {!function(new:MochaJS)} */ (require('mocha'));
const mochaInstance = new Mocha();

const Suite = /** @type {!MochaJSSuite} */ (Mocha.Suite);

Externs

/** @constructor */
const MochaJS = function() {};

/** @function */
MochaJSSuite = function() {};

This is just rough guesses for the types - I'm not familiar enough with Mocha to write the externs without going to hunt down the documentation reference. Hopefully it will point you in the right direction though.