.babelrc

{
	"presets": ["es2015", "stage-1"]
}

package.json

{
  "name": "bluebird-async-warning-test",
  "version": "1.0.0",
  "description": "Bluebird async warning test",
  "author": "Daniel Friesen <[email protected]>",
  "license": "ISC",
  "dependencies": {
    "bluebird": "^3.1.1",
    "babel-core": "^6.3.15",
    "babel-polyfill": "^6.3.14",
    "babel-preset-es2015": "^6.3.13",
    "babel-preset-stage-1": "^6.3.13"
  },
  "private": true
}

test-transformed.js

"use strict";

function _asyncToGenerator(fn) { return function () { var gen = fn.apply(this, arguments); return new Promise(function (resolve, reject) { function step(key, arg) { try { var info = gen[key](arg); var value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { Promise.resolve(value).then(function (value) { step("next", value); }, function (err) { step("throw", err); }); } } step("next"); }); }; }

process.env.NODE_ENV = 'development';
require('babel-polyfill');
var Promise = require('bluebird');

function transformItem(item) {
	return Promise.resolve(item + '-async');
}

Promise.try(_asyncToGenerator(regeneratorRuntime.mark(function _callee() {
	var list, _iteratorNormalCompletion, _didIteratorError, _iteratorError, _iterator, _step, item;

	return regeneratorRuntime.wrap(function _callee$(_context) {
		while (1) {
			switch (_context.prev = _context.next) {
				case 0:
					list = ['foo', 'bar', 'baz'];
					_iteratorNormalCompletion = true;
					_didIteratorError = false;
					_iteratorError = undefined;
					_context.prev = 4;
					_iterator = list[Symbol.iterator]();

				case 6:
					if (_iteratorNormalCompletion = (_step = _iterator.next()).done) {
						_context.next = 16;
						break;
					}

					item = _step.value;
					_context.t0 = console;
					_context.next = 11;
					return transformItem(item);

				case 11:
					_context.t1 = _context.sent;

					_context.t0.log.call(_context.t0, _context.t1);

				case 13:
					_iteratorNormalCompletion = true;
					_context.next = 6;
					break;

				case 16:
					_context.next = 22;
					break;

				case 18:
					_context.prev = 18;
					_context.t2 = _context['catch'](4);
					_didIteratorError = true;
					_iteratorError = _context.t2;

				case 22:
					_context.prev = 22;
					_context.prev = 23;

					if (!_iteratorNormalCompletion && _iterator.return) {
						_iterator.return();
					}

				case 25:
					_context.prev = 25;

					if (!_didIteratorError) {
						_context.next = 28;
						break;
					}

					throw _iteratorError;

				case 28:
					return _context.finish(25);

				case 29:
					return _context.finish(22);

				case 30:
				case 'end':
					return _context.stop();
			}
		}
	}, _callee, this, [[4, 18, 22, 30], [23,, 25, 29]]);
})));

test.js

"use strict";
process.env.NODE_ENV = 'development';
require('babel-polyfill');
var Promise = require('bluebird');

function transformItem(item) {
	return Promise.resolve(item + '-async');
}

Promise.try(async function() {
	var list = ['foo', 'bar', 'baz'];
	for ( let item of list ) {
		console.log(await transformItem(item));
	}
});