Merge pull request #5 from alexcoman/feature/test-utils

Add utilities for tests in order ease the project testing

hnv_client/tests/utils.py

@@ -0,0 +1,111 @@
+# Copyright 2016 Cloudbase Solutions Srl
+#
+#    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.
+
+"""Utilities used in order to ease the project testing."""
+
+# pylint: disable=too-few-public-methods
+
+import functools
+import logging as base_logging
+
+from oslo_log import log as oslo_logging
+
+from hnv_client import config as hnv_conf
+
+
+CONFIG = hnv_conf.CONFIG
+
+
+class SnatchHandler(base_logging.Handler):
+
+    """This is similar with unittest.TestCase.assertLogs from Python 3.4."""
+
+    def __init__(self, *args, **kwargs):
+        super(SnatchHandler, self).__init__(*args, **kwargs)
+        self.output = []
+
+    def emit(self, record):
+        message = self.format(record)
+        self.output.append(message)
+
+
+class LogSnatcher(object):
+    """A context manager to capture emitted logged messages.
+
+    The class can be used as following::
+
+        with LogSnatcher('hnv_client.client') as snatcher:
+            LOG.info("doing stuff")
+            LOG.info("doing stuff %s", 1)
+            LOG.warn("doing other stuff")
+            ...
+        self.assertEqual(snatcher.output,
+                         ['INFO:unknown:doing stuff',
+                          'INFO:unknown:doing stuff 1',
+                          'WARN:unknown:doing other stuff'])
+    """
+
+    @property
+    def output(self):
+        """The snatch handler output."""
+        return self._snatch_handler.output
+
+    def __init__(self, logger_name):
+        self._logger_name = logger_name
+        self._snatch_handler = SnatchHandler()
+        self._logger = oslo_logging.getLogger(self._logger_name)
+        self._previous_level = self._logger.logger.getEffectiveLevel()
+
+    def __enter__(self):
+        self._logger.logger.setLevel(base_logging.DEBUG)
+        self._logger.handlers.append(self._snatch_handler)
+        return self
+
+    def __exit__(self, *args):
+        self._logger.handlers.remove(self._snatch_handler)
+        self._logger.logger.setLevel(self._previous_level)
+
+
+class ConfigPatcher(object):
+    """Override the configuration for the given key, with the given value.
+
+    This class can be used both as a context manager and as a decorator.
+    """
+
+    def __init__(self, key, value, group=None, conf=CONFIG):
+        if group:
+            self._original_value = conf.get(group).get(key)
+        else:
+            self._original_value = conf.get(key)
+        self._key = key
+        self._value = value
+        self._group = group
+        self._config = conf
+
+    def __call__(self, func, *args, **kwargs):
+        def _wrapped_f(*args, **kwargs):
+            with self:
+                return func(*args, **kwargs)
+
+        functools.update_wrapper(_wrapped_f, func)
+        return _wrapped_f
+
+    def __enter__(self):
+        self._config.set_override(self._key, self._value,
+                                  group=self._group)
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self._config.set_override(self._key, self._original_value,
+                                  group=self._group)