Using custom utcnow method in storage.connection to avoid test hacks.

H/T: @tseaver for feedback

gcloud/storage/connection.py

@@ -18,6 +18,15 @@
 from gcloud.storage.iterator import BucketIterator
 
 
+def _utcnow():  # pragma NO COVER
+    """Returns current time as UTC datetime.
+
+    NOTE: This method is here on the module namespace so tests
+          can replace it.
+    """
+    return datetime.datetime.utcnow()
+
+
 class Connection(connection.Connection):
     """A connection to Google Cloud Storage via the JSON REST API.
 
@@ -447,7 +456,7 @@ def _get_expiration_seconds(expiration):
 
         # If it's a timedelta, add it to `now` in UTC.
         if isinstance(expiration, datetime.timedelta):
-            now = datetime.datetime.utcnow().replace(tzinfo=pytz.utc)
+            now = _utcnow().replace(tzinfo=pytz.utc)
             expiration = now + expiration
 
         # If it's a datetime (and/or was a timedelta), convert to a timestamp.

gcloud/storage/test_connection.py

@@ -538,43 +538,14 @@ def test__get_expiration_seconds(self):
         self.assertRaises(TypeError, CALL_FUT, object())
         self.assertRaises(TypeError, CALL_FUT, None)
 
-    def _patch_datetime_for_utcnow(self, datetime_module, *date_tuple):
-        import pytz
-
-        original_datetime = datetime_module.datetime
-
-        class _DateTime(datetime_module.datetime):
-
-            @staticmethod
-            def utcnow():
-                return _DateTime(*date_tuple, tzinfo=pytz.utc)
-
-            def replace(self, *args, **kwargs):
-                result = original_datetime.replace(self, *args, **kwargs)
-                # Cast to the correct type so isinstance() succeeds.
-                return _DateTime(result.year, result.month, result.day,
-                                 result.hour, result.minute, result.second,
-                                 result.microsecond, tzinfo=result.tzinfo)
-
-            def __add__(self, other):
-                result = original_datetime.__add__(self, other)
-                # Cast to the correct type so isinstance() succeeds.
-                return _DateTime(result.year, result.month, result.day,
-                                 result.hour, result.minute, result.second,
-                                 result.microsecond, tzinfo=result.tzinfo)
-
-        self._original_datetime_class = datetime_module.datetime
-        datetime_module.datetime = _DateTime
-
-    def _restore_datetime(self, datetime_module):
-        datetime_module.datetime = self._original_datetime_class
-
     def test__get_expiration_seconds_w_timedelta(self):
+        # Patch the utcnow method on the module.
         import datetime
+        from gcloud.storage import connection
+        original_utcnow = connection._utcnow
+        connection._utcnow = lambda: datetime.datetime(2004, 8, 19, 0, 0, 0, 0)
 
-        self._patch_datetime_for_utcnow(datetime, 2004, 8, 19, 0, 0, 0, 0)
-        # Must do this after patching datetime so that the import
-        # occurs again with the patched datetime.
+        # Test the function with timedelta inputs.
         CALL_FUT = self._getTargetClass()._get_expiration_seconds
 
         expiration_as_seconds = 1092873600
@@ -586,7 +557,8 @@ def test__get_expiration_seconds_w_timedelta(self):
         self.assertEqual(expiration_as_seconds + 10,
                          CALL_FUT(expiration_as_delta))
 
-        self._restore_datetime(datetime)
+        # Restore utcnow method on the module.
+        connection._utcnow = original_utcnow
 
 
 class Http(object):