diff --git a/tests/test_oauth2client.py b/tests/test_oauth2client.py
new file mode 100644
index 0000000..9f30eff
--- /dev/null
+++ b/tests/test_oauth2client.py
@@ -0,0 +1,172 @@
+#!/usr/bin/python2.4
+#
+# Copyright 2010 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+"""Discovery document tests
+
+Unit tests for objects created from discovery documents.
+"""
+
+__author__ = 'jcgregorio@google.com (Joe Gregorio)'
+
+import unittest
+import urlparse
+try:
+    from urlparse import parse_qs
+except ImportError:
+    from cgi import parse_qs
+
+from apiclient.http import HttpMockSequence
+from oauth2client.client import AccessTokenCredentials
+from oauth2client.client import AccessTokenCredentialsError
+from oauth2client.client import AccessTokenRefreshError
+from oauth2client.client import FlowExchangeError
+from oauth2client.client import OAuth2Credentials
+from oauth2client.client import OAuth2WebServerFlow
+
+
+class OAuth2CredentialsTests(unittest.TestCase):
+
+  def setUp(self):
+    access_token = "foo"
+    client_id = "some_client_id"
+    client_secret = "cOuDdkfjxxnv+"
+    refresh_token = "1/0/a.df219fjls0"
+    token_expiry = "ignored"
+    token_uri = "https://www.google.com/accounts/o8/oauth2/token"
+    user_agent = "refresh_checker/1.0"
+    self.credentials = OAuth2Credentials(
+      access_token, client_id, client_secret,
+      refresh_token, token_expiry, token_uri,
+      user_agent)
+
+  def test_token_refresh_success(self):
+    http = HttpMockSequence([
+      ({'status': '401'}, ''),
+      ({'status': '200'}, '{"access_token":"1/3w","expires_in":3600}'),
+      ({'status': '200'}, 'echo_request_headers'),
+      ])
+    http = self.credentials.authorize(http)
+    resp, content = http.request("http://example.com")
+    self.assertEqual(content['authorization'], 'OAuth 1/3w')
+
+  def test_token_refresh_failure(self):
+    http = HttpMockSequence([
+      ({'status': '401'}, ''),
+      ({'status': '400'}, '{"error":"access_denied"}'),
+      ])
+    http = self.credentials.authorize(http)
+    try:
+      http.request("http://example.com")
+      self.fail("should raise AccessTokenRefreshError exception")
+    except AccessTokenRefreshError:
+      pass
+
+  def test_non_401_error_response(self):
+    http = HttpMockSequence([
+      ({'status': '400'}, ''),
+      ])
+    http = self.credentials.authorize(http)
+    resp, content = http.request("http://example.com")
+    self.assertEqual(400, resp.status)
+
+
+class AccessTokenCredentialsTests(unittest.TestCase):
+
+  def setUp(self):
+    access_token = "foo"
+    user_agent = "refresh_checker/1.0"
+    self.credentials = AccessTokenCredentials(access_token, user_agent)
+
+  def test_token_refresh_success(self):
+    http = HttpMockSequence([
+      ({'status': '401'}, ''),
+      ])
+    http = self.credentials.authorize(http)
+    try:
+      resp, content = http.request("http://example.com")
+      self.fail("should throw exception if token expires")
+    except AccessTokenCredentialsError:
+      pass
+    except Exception:
+      self.fail("should only throw AccessTokenCredentialsError")
+
+  def test_non_401_error_response(self):
+    http = HttpMockSequence([
+      ({'status': '400'}, ''),
+      ])
+    http = self.credentials.authorize(http)
+    resp, content = http.request("http://example.com")
+    self.assertEqual(400, resp.status)
+
+
+class OAuth2WebServerFlowTest(unittest.TestCase):
+
+  def setUp(self):
+    self.flow = OAuth2WebServerFlow(
+        client_id='client_id+1',
+        client_secret='secret+1',
+        scope='foo',
+        user_agent='unittest-sample/1.0',
+        )
+
+  def test_construct_authorize_url(self):
+    authorize_url = self.flow.step1_get_authorize_url('oob')
+
+    parsed = urlparse.urlparse(authorize_url)
+    q = parse_qs(parsed[4])
+    self.assertEqual(q['client_id'][0], 'client_id+1')
+    self.assertEqual(q['response_type'][0], 'code')
+    self.assertEqual(q['scope'][0], 'foo')
+    self.assertEqual(q['redirect_uri'][0], 'oob')
+
+  def test_exchange_failure(self):
+    http = HttpMockSequence([
+      ({'status': '400'}, '{"error":"invalid_request"}')
+      ])
+
+    try:
+      credentials = self.flow.step2_exchange('some random code', http)
+      self.fail("should raise exception if exchange doesn't get 200")
+    except FlowExchangeError:
+      pass
+
+  def test_exchange_success(self):
+    http = HttpMockSequence([
+      ({'status': '200'},
+      """{ "access_token":"SlAV32hkKG",
+       "expires_in":3600,
+       "refresh_token":"8xLOxBtZp8" }"""),
+      ])
+
+    credentials = self.flow.step2_exchange('some random code', http)
+    self.assertEqual(credentials.access_token, 'SlAV32hkKG')
+    self.assertNotEqual(credentials.token_expiry, None)
+    self.assertEqual(credentials.refresh_token, '8xLOxBtZp8')
+
+
+  def test_exchange_no_expires_in(self):
+    http = HttpMockSequence([
+      ({'status': '200'}, """{ "access_token":"SlAV32hkKG",
+       "refresh_token":"8xLOxBtZp8" }"""),
+      ])
+
+    credentials = self.flow.step2_exchange('some random code', http)
+    self.assertEqual(credentials.token_expiry, None)
+
+
+if __name__ == '__main__':
+  unittest.main()