[IMP] web:tests: patch Date.now

Before this commit, when we use `testUtils.patchDate`,
the function `Date.now` was not using the fake date for reference.

This is an issue with the lib momentjs, which instantiate the
current date as follow:

```
new Date(Date.now())
```

Because of this, we were handling patched date and unpatched moment
objects.

Task-ID 1902848

addons/web/static/tests/helpers/test_utils_mock.js

@@ -446,7 +446,13 @@ function patchDate(year, month, day, hours, minutes, seconds) {
         }
 
         // Copy "native" methods explicitly; they may be non-enumerable
-        Date.now = NativeDate.now;
+        // exception: 'now' uses fake date as reference
+        Date.now = function () {
+            var date = new NativeDate();
+            var time = date.getTime();
+            time -= timeInterval;
+            return time;
+        };
         Date.UTC = NativeDate.UTC;
         Date.prototype = NativeDate.prototype;
         Date.prototype.constructor = Date;

addons/web/static/tests/helpers/test_utils_tests.js

@@ -0,0 +1,36 @@
+odoo.define('web.testUtilsTests', function (require) {
+"use strict";
+
+var testUtils = require('web.test_utils');
+
+QUnit.module('web', {}, function () {
+QUnit.module('testUtils', {}, function () {
+
+QUnit.module('patch date');
+
+QUnit.test('new date', function (assert) {
+    assert.expect(5);
+    const unpatchDate = testUtils.mock.patchDate(2018, 9, 23, 14, 50, 0);
+
+    const date = new Date();
+
+    assert.strictEqual(date.getFullYear(), 2018);
+    assert.strictEqual(date.getMonth(), 9);
+    assert.strictEqual(date.getDate(), 23);
+    assert.strictEqual(date.getHours(), 14);
+    assert.strictEqual(date.getMinutes(), 50);
+    unpatchDate();
+});
+
+QUnit.test('new moment', function (assert) {
+    assert.expect(1);
+    const unpatchDate = testUtils.mock.patchDate(2018, 9, 23, 14, 50, 0);
+
+    const m = moment();
+    assert.strictEqual(m.format('YYYY-MM-DD HH:mm'), '2018-10-23 14:50');
+    unpatchDate();
+});
+
+});
+});
+});

addons/web/views/webclient_templates.xml

@@ -704,6 +704,8 @@
                 <script type="text/javascript" src="/web/static/tests/widgets/rainbow_man_tests.js"/>
 
                 <script type="text/javascript" src="/web/static/tests/tools/debug_manager_tests.js"/>
+                
+                <script type="text/javascript" src="/web/static/tests/helpers/test_utils_tests.js"></script>
             </t>
 
             <div id="qunit"/>