https://github.com/requests/requests-oauthlib/commit/7057cbee773c1dff1856730ca661cc71abb2506e.diff
https://github.com/requests/requests-oauthlib/commit/8c2c96c4bb45803df2779cfde90868445977ab96.diff
diff --git a/tests/test_oauth2_session.py b/tests/test_oauth2_session.py
index 305241a..cf095a5 100644
--- a/tests/test_oauth2_session.py
+++ b/tests/test_oauth2_session.py
@@ -1,6 +1,7 @@
 from __future__ import unicode_literals
 import json
 import mock
+import time
 import unittest
 
 from oauthlib.common import urlencode
@@ -11,6 +11,9 @@
 from requests_oauthlib import OAuth2Session, TokenUpdated
 
 
+fake_time = time.time()
+
+
 class OAuth2SessionTest(unittest.TestCase):
 
     def setUp(self):
@@ -22,7 +25,8 @@ def setUp(self):
             'token_type': 'Bearer',
             'access_token': 'asdfoiw37850234lkjsdfsdf',
             'refresh_token': 'sldvafkjw34509s8dfsdf',
-            'expires_in': '3600'
+            'expires_in': '3600',
+            'expires_at': fake_time + 3600,
         }
         self.client_id = 'foo'
         self.clients = [
@@ -66,9 +70,11 @@ def test_authorization_url(self):
         self.assertIn(self.client_id, auth_url)
         self.assertIn('response_type=token', auth_url)
 
+    @mock.patch("time.time", new=lambda: fake_time)
     def test_refresh_token_request(self):
         self.expired_token = dict(self.token)
         self.expired_token['expires_in'] = '-1'
+        del self.expired_token['expires_at']
 
         def fake_refresh(r, **kwargs):
             resp = mock.MagicMock()
@@ -98,12 +104,14 @@ def token_updater(token):
             auth.send = fake_refresh
             auth.get('https://i.b')
 
+    @mock.patch("time.time", new=lambda: fake_time)
     def test_token_from_fragment(self):
         mobile = MobileApplicationClient(self.client_id)
         response_url = 'https://i.b/callback#' + urlencode(self.token.items())
         auth = OAuth2Session(client=mobile)
         self.assertEqual(auth.token_from_fragment(response_url), self.token)
 
+    @mock.patch("time.time", new=lambda: fake_time)
     def test_fetch_token(self):
         def fake_token(token):
             def fake_send(r, **kwargs):