added unit testing, and started implementing unit tests...phew

node_modules/async/wrapSync.js

@@ -0,0 +1,110 @@
+'use strict';
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+exports.default = asyncify;
+
+var _isObject = require('lodash/isObject');
+
+var _isObject2 = _interopRequireDefault(_isObject);
+
+var _initialParams = require('./internal/initialParams');
+
+var _initialParams2 = _interopRequireDefault(_initialParams);
+
+var _setImmediate = require('./internal/setImmediate');
+
+var _setImmediate2 = _interopRequireDefault(_setImmediate);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+/**
+ * Take a sync function and make it async, passing its return value to a
+ * callback. This is useful for plugging sync functions into a waterfall,
+ * series, or other async functions. Any arguments passed to the generated
+ * function will be passed to the wrapped function (except for the final
+ * callback argument). Errors thrown will be passed to the callback.
+ *
+ * If the function passed to `asyncify` returns a Promise, that promises's
+ * resolved/rejected state will be used to call the callback, rather than simply
+ * the synchronous return value.
+ *
+ * This also means you can asyncify ES2017 `async` functions.
+ *
+ * @name asyncify
+ * @static
+ * @memberOf module:Utils
+ * @method
+ * @alias wrapSync
+ * @category Util
+ * @param {Function} func - The synchronous function, or Promise-returning
+ * function to convert to an {@link AsyncFunction}.
+ * @returns {AsyncFunction} An asynchronous wrapper of the `func`. To be
+ * invoked with `(args..., callback)`.
+ * @example
+ *
+ * // passing a regular synchronous function
+ * async.waterfall([
+ *     async.apply(fs.readFile, filename, "utf8"),
+ *     async.asyncify(JSON.parse),
+ *     function (data, next) {
+ *         // data is the result of parsing the text.
+ *         // If there was a parsing error, it would have been caught.
+ *     }
+ * ], callback);
+ *
+ * // passing a function returning a promise
+ * async.waterfall([
+ *     async.apply(fs.readFile, filename, "utf8"),
+ *     async.asyncify(function (contents) {
+ *         return db.model.create(contents);
+ *     }),
+ *     function (model, next) {
+ *         // `model` is the instantiated model object.
+ *         // If there was an error, this function would be skipped.
+ *     }
+ * ], callback);
+ *
+ * // es2017 example, though `asyncify` is not needed if your JS environment
+ * // supports async functions out of the box
+ * var q = async.queue(async.asyncify(async function(file) {
+ *     var intermediateStep = await processFile(file);
+ *     return await somePromise(intermediateStep)
+ * }));
+ *
+ * q.push(files);
+ */
+function asyncify(func) {
+    return (0, _initialParams2.default)(function (args, callback) {
+        var result;
+        try {
+            result = func.apply(this, args);
+        } catch (e) {
+            return callback(e);
+        }
+        // if result is Promise object
+        if ((0, _isObject2.default)(result) && typeof result.then === 'function') {
+            result.then(function (value) {
+                invokeCallback(callback, null, value);
+            }, function (err) {
+                invokeCallback(callback, err.message ? err : new Error(err));
+            });
+        } else {
+            callback(null, result);
+        }
+    });
+}
+
+function invokeCallback(callback, error, value) {
+    try {
+        callback(error, value);
+    } catch (e) {
+        (0, _setImmediate2.default)(rethrow, e);
+    }
+}
+
+function rethrow(error) {
+    throw error;
+}
+module.exports = exports['default'];