Fix ClientException message property not set properly

To reproduce:

    >>> from keystoneauth1 import exceptions
    >>> e = exceptions.ClientException(message="test")
    >>> print(e.message)
    None

Change-Id: If73df85768866fb93d90ff95479f29f64aabe73f
Co-Authored-By: Gage Hugo <gagehugo@gmail.com>
Closes-Bug: #1534363

keystoneauth1/exceptions/base.py

@@ -17,12 +17,8 @@ __all__ = ('ClientException',)
 class ClientException(Exception):
     """The base exception for everything to do with clients."""
 
-    message = None
+    message = "ClientException"
 
     def __init__(self, message=None):
-        if not message:
-            if self.message:
-                message = self.message
-            else:
-                message = self.__class__.__name__
-        super(Exception, self).__init__(message)
+        self.message = message or self.message
+        super(ClientException, self).__init__(self.message)

keystoneauth1/tests/unit/exceptions/test_exceptions.py

@@ -0,0 +1,32 @@
+# 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.
+
+from keystoneauth1 import exceptions
+from keystoneauth1.tests.unit import utils
+
+
+class ExceptionTests(utils.TestCase):
+
+    def test_clientexception_with_message(self):
+        test_message = 'Unittest exception message.'
+        exc = exceptions.ClientException(message=test_message)
+        self.assertEqual(test_message, exc.message)
+
+    def test_clientexception_with_no_message(self):
+        exc = exceptions.ClientException()
+        self.assertEqual(exceptions.ClientException.__name__,
+                         exc.message)
+
+    def test_using_default_message(self):
+        exc = exceptions.AuthorizationFailure()
+        self.assertEqual(exceptions.AuthorizationFailure.message,
+                         exc.message)