Do not attempt to refresh when RT is unavailable

adal/cache_driver.py

@@ -164,11 +164,13 @@ def _refresh_entry_if_necessary(self, entry, is_resource_specific):
         now_plus_buffer = now + timedelta(minutes=Misc.CLOCK_BUFFER)
 
         if is_resource_specific and now_plus_buffer > expiry_date:
-            self._log.info('Cached token is expired.  Refreshing: %s', expiry_date)
-            return self._refresh_expired_entry(entry)
+            if TokenResponseFields.REFRESH_TOKEN in entry:
+                self._log.info('Cached token is expired.  Refreshing: %s', expiry_date)
+                return self._refresh_expired_entry(entry)
         elif not is_resource_specific and entry.get(TokenResponseFields.IS_MRRT):
-            self._log.info('Acquiring new access token from MRRT token.')
-            return self._acquire_new_token_from_mrrt(entry)
+            if TokenResponseFields.REFRESH_TOKEN in entry:
+                self._log.info('Acquiring new access token from MRRT token.')
+                return self._acquire_new_token_from_mrrt(entry)
         else:
             return entry
 

tests/test_cache_driver.py

@@ -0,0 +1,58 @@
+#------------------------------------------------------------------------------
+#
+# Copyright (c) Microsoft Corporation.
+# All rights reserved.
+#
+# This code is licensed under the MIT License.
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files(the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions :
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+#
+#------------------------------------------------------------------------------
+
+import unittest
+try:
+    from unittest import mock
+except ImportError:
+    import mock
+
+from adal.log import create_log_context
+from adal.cache_driver import CacheDriver
+
+
+class TestCacheDriver(unittest.TestCase):
+    def test_rt_less_item_wont_cause_exception(self):  # Github issue #82
+        rt_less_entry_came_from_previous_client_credentials_grant = {
+            "expiresIn": 3600,
+            "_authority": "https://login.microsoftonline.com/foo",
+            "resource": "spn:00000002-0000-0000-c000-000000000000",
+            "tokenType": "Bearer",
+            "expiresOn": "1999-05-22 16:31:46.202000",
+            "isMRRT": True,
+            "_clientId": "client_id",
+            "accessToken": "this is an AT",
+            }
+        refresh_function = mock.MagicMock(return_value={})
+        cache_driver = CacheDriver(
+            {"log_context": create_log_context()}, "authority", "resource",
+            "client_id", mock.MagicMock(), refresh_function)
+        entry = cache_driver._refresh_entry_if_necessary(
+            rt_less_entry_came_from_previous_client_credentials_grant, False)
+        refresh_function.assert_not_called()  # Otherwise it will cause an exception
+        self.assertIsNone(entry)
+