Rework exceptions

This patch is reworking the exceptions that can be raised from Sushy,
before this patch many errors such as HTTP 4XX or 5XX were failing
silently.

This patch add custom exceptions for cases such as ConnectionError and
HTTPError that can be raised from requests.

Change-Id: I57ff8dffdfe0ab763bd0194e1916db8ae7a7861d

sushy/connector.py

@@ -19,6 +19,8 @@ import os
 
 import requests
 
+from sushy import exceptions
+
 LOG = logging.getLogger(__name__)
 
 
@@ -52,7 +54,20 @@ class Connector(object):
                       'the headers "%(headers)s" and data "%(data)s"',
                       {'method': method, 'url': url, 'headers': headers,
                        'data': data or ''})
-            return session.request(method, url, data=data)
+            try:
+                response = session.request(method, url, data=data)
+            except requests.ConnectionError as e:
+                raise exceptions.ConnectionError(url=url, error=e)
+
+            LOG.debug('Response: Status code: %d', response.status_code)
+            try:
+                response.raise_for_status()
+            except requests.HTTPError as e:
+                raise exceptions.HTTPError(
+                    method=method, url=url, error=e,
+                    status_code=e.response.status_code)
+
+            return response
 
     def get(self, path='', data=None, headers=None):
         return self._op('GET', path, data, headers)

sushy/exceptions.py

@@ -15,29 +15,49 @@
 
 
 class SushyError(Exception):
+    """Basic exception for errors raised by Sushy"""
+
     message = None
 
-    def __init__(self, message=None, **kwargs):
+    def __init__(self, **kwargs):
         if self.message and kwargs:
             self.message = self.message % kwargs
-        else:
-            self.message = message
 
         super(SushyError, self).__init__(self.message)
 
 
-class ResourceNotFoundError(SushyError):
+class ConnectionError(SushyError):
-    message = 'Resource %(resource)s not found'
+    message = 'Unable to connect to %(url)s. Error: %(error)s'
 
 
 class MissingAttributeError(SushyError):
-    message = 'The attribute %(attribute)s is missing in %(resource)s'
+    message = ('The attribute %(attribute)s is missing from the '
+               'resource %(resource)s')
 
 
 class MissingActionError(SushyError):
-    message = 'The action %(action)s is missing in %(resource)s'
+    message = ('The action %(action)s is missing from the '
+               'resource %(resource)s')
 
 
 class InvalidParameterValueError(SushyError):
     message = ('The parameter "%(parameter)s" value "%(value)s" is invalid. '
                'Valid values are: %(valid_values)s')
+
+
+class HTTPError(SushyError):
+    """Basic exception for HTTP errors"""
+
+    status_code = None
+    message = ('Error issuing a %(method)s request at %(url)s. '
+               'Error: %(error)s')
+
+    def __init__(self, status_code=None, **kwargs):
+        super(HTTPError, self).__init__(**kwargs)
+        if status_code is not None:
+            self.status_code = status_code
+
+
+class ResourceNotFoundError(HTTPError):
+    status_code = 404
+    message = 'Resource %(resource)s not found'

sushy/resources/base.py

@@ -16,7 +16,6 @@
 import abc
 
 import six
-from six.moves import http_client
 
 from sushy import exceptions
 
@@ -31,9 +30,12 @@ class ResourceBase(object):
         self.refresh()
 
     def refresh(self):
-        resp = self._conn.get(path=self._path)
+        try:
-        if resp.status_code == http_client.NOT_FOUND:
+            resp = self._conn.get(path=self._path)
-            raise exceptions.ResourceNotFoundError(resource=self._path)
+        except exceptions.HTTPError as e:
+            if e.status_code == 404:
+                raise exceptions.ResourceNotFoundError(resource=self._path)
+            raise
 
         self._json = resp.json()
         self._parse_attributes()

sushy/tests/unit/resources/test_base.py

@@ -0,0 +1,55 @@
+# Copyright 2017 Red Hat, Inc.
+# All Rights Reserved.
+#
+#    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 mock
+
+from sushy import exceptions
+from sushy.resources import base as resource_base
+from sushy.tests.unit import base
+
+
+class BaseResouce(resource_base.ResourceBase):
+
+    def _parse_attributes(self):
+        pass
+
+
+class ResourceBaseTestCase(base.TestCase):
+
+    def setUp(self):
+        super(ResourceBaseTestCase, self).setUp()
+        self.conn = mock.Mock()
+        self.base_resource = BaseResouce(connector=self.conn, path='/Foo')
+        # refresh() is called in the constructor
+        self.conn.reset_mock()
+
+    def test_refresh(self):
+        self.base_resource.refresh()
+        self.conn.get.assert_called_once_with(path='/Foo')
+
+    def test_refresh_http_error_reraised(self):
+        self.conn.get.side_effect = exceptions.HTTPError(
+            method='GET', url='http://foo.bar:8000/redfish/v1', error='boom',
+            status_code=404)
+        self.assertRaises(exceptions.ResourceNotFoundError,
+                          self.base_resource.refresh)
+        self.conn.get.assert_called_once_with(path='/Foo')
+
+    def test_refresh_resource_not_found(self):
+        self.conn.get.side_effect = exceptions.HTTPError(
+            method='GET', url='http://foo.bar:8000/redfish/v1', error='boom',
+            status_code=400)
+        self.assertRaises(exceptions.HTTPError, self.base_resource.refresh)
+        self.conn.get.assert_called_once_with(path='/Foo')

sushy/tests/unit/test_connector.py

@@ -14,8 +14,10 @@
 #    under the License.
 
 import mock
+import requests
 
 from sushy import connector
+from sushy import exceptions
 from sushy.tests.unit import base
 
 
@@ -68,3 +70,22 @@ class ConnectorTestCase(base.TestCase):
     def test__op_no_headers(self):
         expected_headers = {'Content-Type': 'application/json'}
         self._test_op(None, expected_headers)
+
+    @mock.patch('sushy.connector.requests.Session', autospec=True)
+    def test__op_connection_error(self, mock_session):
+        fake_session = mock.Mock()
+        mock_session.return_value.__enter__.return_value = fake_session
+        fake_session.request.side_effect = requests.exceptions.ConnectionError
+
+        self.assertRaises(exceptions.ConnectionError, self.conn._op, 'GET')
+
+    @mock.patch('sushy.connector.requests.Session', autospec=True)
+    def test__op_http_error(self, mock_session):
+        fake_session = mock.Mock()
+        mock_session.return_value.__enter__.return_value = fake_session
+        fake_response = fake_session.request.return_value
+        fake_response.status_code = 400
+        fake_response.raise_for_status.side_effect = (
+            requests.exceptions.HTTPError(response=fake_response))
+
+        self.assertRaises(exceptions.HTTPError, self.conn._op, 'GET')