fix(isDate): Timezone Offset Fix (#2257)

* Timezone Offset Fix & Parsing with Leading Zeros

* `isDate` Timezone Mock Test, Support for NodeJS <8

* `isDate` Unit Test Resiliency Improvement

Author: tomaspanek

package.json

@@ -51,6 +51,7 @@
     "rimraf": "^3.0.0",
     "rollup": "^0.47.0",
     "rollup-plugin-babel": "^4.0.1",
+    "timezone-mock": "^1.3.6",
     "uglify-js": "^3.0.19"
   },
   "scripts": {

src/lib/isDate.js

@@ -65,7 +65,19 @@ export default function isDate(input, options) {
       }
     }
 
-    return new Date(`${fullYear}-${dateObj.m}-${dateObj.d}`).getDate() === +dateObj.d;
+    let month = dateObj.m;
+
+    if (dateObj.m.length === 1) {
+      month = `0${dateObj.m}`;
+    }
+
+    let day = dateObj.d;
+
+    if (dateObj.d.length === 1) {
+      day = `0${dateObj.d}`;
+    }
+
+    return new Date(`${fullYear}-${month}-${day}T00:00:00.000Z`).getUTCDate() === +dateObj.d;
   }
 
   if (!options.strictMode) {

test/validators.test.js

@@ -1,5 +1,6 @@
 import assert from 'assert';
 import fs from 'fs';
+import timezone_mock from 'timezone-mock';
 import { format } from 'util';
 import vm from 'vm';
 import validator from '../src/index';
@@ -13054,6 +13055,17 @@ describe('Validators', () => {
         '29.02.2020',
       ],
     });
+    // emulating Pacific time zone offset & time
+    // which could potentially result in UTC conversion issues
+    timezone_mock.register('US/Pacific');
+    test({
+      validator: 'isDate',
+      valid: [
+        new Date(2016, 2, 29),
+        '2017-08-04',
+      ],
+    });
+    timezone_mock.unregister();
   });
   it('should validate time', () => {
     test({