feature: if the provided date is 'now', create a date (#14)

test/util/underscore.js

@@ -0,0 +1,17 @@
+const chai = require("chai");
+const expect = chai.expect;
+const _ = require('../../src/util/underscore.js');
+
+describe('util/underscore', function() {
+    describe('.isString()', function(){
+        it('should return true for literal string', function(){
+            expect(_.isString('foo')).to.be.true;
+        });
+        it('should return true String instance', function(){
+            expect(_.isString(new String('foo'))).to.be.true;
+        });
+        it('should return false for 123 ', function(){
+            expect(_.isString(123)).to.be.false;
+        });
+    });
+});