Add test for OAuth Mutual TLS.

Author: Daniel Fett

tests/test_oauth2_session.py

@@ -78,6 +78,25 @@ def verifier(r, **kwargs):
             sess.send = verifier
             sess.get("https://i.b")
 
+    def test_mtls(self):
+        cert = ('testsomething.example-client.pem', 'testsomething.example-client-key.pem')
+        def verifier(r, **kwargs):
+            self.assertIn('cert', kwargs)
+            self.assertEqual(cert, kwargs['cert'])
+            self.assertIn('client_id=' + self.client_id, r.body)
+            resp = mock.MagicMock()
+            resp.text = json.dumps(self.token)
+            return resp
+
+        for client in self.clients:
+            sess = OAuth2Session(client=client)
+            sess.send = verifier
+            
+            if isinstance(client, LegacyApplicationClient):
+                sess.fetch_token('https://i.b', include_client_id=True, cert=cert, username="username1", password="password1")
+            else:
+                sess.fetch_token('https://i.b', include_client_id=True, cert=cert)
+
     def test_authorization_url(self):
         url = "https://example.com/authorize?foo=bar"