Adding fancy exceptions messages

OneViewException and its subclasses are meant to have a default message that can
be overwritten by passing a custom message in the instantiation method. This
patch ensure it happens without aid of the builtin class Exception and
overwrite __str__ to include information about the class of the exception being
thrown to ease debug.

To obtain just the exception message, users can still access the exc.message
variable.

Change-Id: I278e38dadf9b612009156ecfce62a0d31e9caa94

oneview_client/exceptions.py

@@ -19,6 +19,13 @@
 class OneViewException(Exception):
     message = ("An error occurred in the OneView client.")
 
+    def __init__(self, msg=None):
+        if msg:
+            self.message = msg
+
+    def __str__(self):
+        return "<%s> %s" % (self.__class__.__name__, self.message)
+
 
 class OneViewConnectionError(OneViewException):
     message = ("Can't connect to OneView")

oneview_client/tests/test_exceptions.py

@@ -0,0 +1,38 @@
+# -*- encoding: utf-8 -*-
+#
+# (c) Copyright 2015 Hewlett Packard Enterprise Development LP
+# Copyright 2015 Universidade Federal de Campina Grande
+#
+#    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.
+
+import unittest
+
+from oneview_client import exceptions
+
+
+class Test(unittest.TestCase):
+
+    def test_create_OneViewException_default_message(self):
+        exc = exceptions.OneViewException()
+        self.assertEqual(
+            str(exc),
+            "<%s> %s" % (exc.__class__.__name__, exc.message)
+        )
+
+    def test_create_OneViewException_message(self):
+        msg = "This is a custom message"
+        exc = exceptions.OneViewException(msg)
+        self.assertEqual(
+            str(exc),
+            "<%s> %s" % (exc.__class__.__name__, msg)
+        )