Basic ES6 Promise.then synchronous monkey patch

gistfile1.js

Promise.prototype.then = function (good, bad) {
  this.chain_ = this.chain_ || [];
  this.chain_.push({resolve: good, reject: bad});
  return this;
}

Promise.prototype.resolveNext_ = function () {
  if (!this.chain_) return;
  var next = this.chain_.shift(), nextVal;
  if (!next) return;

  if (this.resolvedVal) {
    next = next.resolve;
  }
  else {
    next = next.reject;
  }

  nextVal = next ? next.call(this, this.resolvedVal) : null;
  nextVal && this.resolveNext_();
}

it('should resolve synchronously', function() {
  var orderOfExecution = [],
      p = new Promise(function (resolve, reject) {
        //Nothing in here does anything.
      });

  p.then(function() {
    orderOfExecution.push('thenResolve');
  });

  mockResolve_(p, 'value');
  flush(p);

  orderOfExecution.push('postFlush');

  expect(orderOfExecution[0]).toBe('thenResolve');
  expect(orderOfExecution[1]).toBe('postFlush');
  expect(orderOfExecution[2]).toBeUndefined();
});