[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

1 files changed, 7 insertions, 1 deletions

diff --git a/addons/web/static/tests/helpers/test_utils_mock.js b/addons/web/static/tests/helpers/test_utils_mock.js
index 5f567e714bc..8758d162a7b 100644
--- a/addons/web/static/tests/helpers/test_utils_mock.js
+++ b/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;