chai-spies: How to test async callbacks

foo.js

const Chai = require('chai');
const Spies = require('chai-spies');

Chai.use(Spies);

const original = function(callback) {
  setTimeout(callback, 0);
};

it("async callback should be called with Spy", function() {
  const callback = Chai.spy();

  original(callback);

  // Doesn't work here.
  Chai.expect(callback).to.have.been.called();
});

it("async callback should be called without Spy", function(done) {
  // Does work.
  original(() => done());
});