Add an example to show simple mocking of datetime.datetime object.

mocking_datetime.py

@@ -0,0 +1,35 @@
+import datetime
+import unittest
+import unittest.mock as mock
+
+
+class MockDatetimeTest(unittest.TestCase):
+
+    def setUp(self):
+        datetime_patcher = mock.patch.object(
+            datetime, 'datetime',
+            mock.Mock(wraps=datetime.datetime)
+        )
+        mocked_datetime = datetime_patcher.start()
+        mocked_datetime.today.return_value = datetime.datetime(2012, 6, 16)
+        self.addCleanup(datetime_patcher.stop)
+
+    def test_datetime(self):
+        self.assertEqual(
+            datetime.datetime.today(),
+            datetime.datetime(2012, 6, 16)
+        )
+
+
+class MockDatetimeDecoratorTest(unittest.TestCase):
+
+    @mock.patch.object(datetime, 'datetime')
+    def test_datetime(self, mocked_datetime):
+        mocked_datetime.today.return_value = datetime.datetime(2012, 6, 16)
+        self.assertEqual(
+            datetime.datetime.today(),
+            datetime.datetime(2012, 6, 16)
+        )
+
+if __name__ == '__main__':
+    unittest.main()