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

node_modules/async/constant.js

@@ -0,0 +1,66 @@
+'use strict';
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+
+exports.default = function () /*...values*/{
+    var values = (0, _slice2.default)(arguments);
+    var args = [null].concat(values);
+    return function () /*...ignoredArgs, callback*/{
+        var callback = arguments[arguments.length - 1];
+        return callback.apply(this, args);
+    };
+};
+
+var _slice = require('./internal/slice');
+
+var _slice2 = _interopRequireDefault(_slice);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+;
+
+/**
+ * Returns a function that when called, calls-back with the values provided.
+ * Useful as the first function in a [`waterfall`]{@link module:ControlFlow.waterfall}, or for plugging values in to
+ * [`auto`]{@link module:ControlFlow.auto}.
+ *
+ * @name constant
+ * @static
+ * @memberOf module:Utils
+ * @method
+ * @category Util
+ * @param {...*} arguments... - Any number of arguments to automatically invoke
+ * callback with.
+ * @returns {AsyncFunction} Returns a function that when invoked, automatically
+ * invokes the callback with the previous given arguments.
+ * @example
+ *
+ * async.waterfall([
+ *     async.constant(42),
+ *     function (value, next) {
+ *         // value === 42
+ *     },
+ *     //...
+ * ], callback);
+ *
+ * async.waterfall([
+ *     async.constant(filename, "utf8"),
+ *     fs.readFile,
+ *     function (fileData, next) {
+ *         //...
+ *     }
+ *     //...
+ * ], callback);
+ *
+ * async.auto({
+ *     hostname: async.constant("https://server.net/"),
+ *     port: findFreePort,
+ *     launchServer: ["hostname", "port", function (options, cb) {
+ *         startServer(options, cb);
+ *     }],
+ *     //...
+ * }, callback);
+ */
+module.exports = exports['default'];