Minor refactor

1. SingletonMeta -> modified to allow handling multiple classes and moved to metaclasses too.
2. @logwrap : process asserts too

Changes reason:
 @logwrap was changed during test debug (was assert in wrapped function
 and stacktrace was not enough for reason understand) and moved out of
 test changest due to not mandatory for this test.
 Pros: Now assert, raised in wrapped function is recorded in log with
 details.

 SingletonMeta: was changed as "nice to have" during work on plugin
 helpers. Later plugin helpers was moved out of SshManager, and all code
 changes was moved to this changeset.
 Pros: Single way for handling the same tasks in different places.
 Previously SshManager used Metaclass, which could not be reused for
 more, than one class and Environment used __new__ directly written
 in class code.

Related-Bug: #1518979
Related-Bug: #1519050

Change-Id: I798302879400747909229cc208f97a669f25bbf3

doc/helpers.rst

@@ -28,6 +28,11 @@ Decorators
 .. automodule:: fuelweb_test.helpers.decorators
    :members:
 
+Metaclasses
+-----------
+.. automodule:: fuelweb_test.helpers.metaclasses
+   :members:
+
 Eb tables
 ---------
 .. automodule:: fuelweb_test.helpers.eb_tables

fuelweb_test/__init__.py

@@ -13,6 +13,7 @@
 #    under the License.
 import functools
 import logging
+import traceback
 import os
 from fuelweb_test.settings import LOGS_DIR
 
@@ -54,9 +55,17 @@ def debug(logger):
                     func.__name__, args, kwargs
                 )
             )
-            result = func(*args, **kwargs)
-            logger.debug(
-                "Done: {} with result: {}".format(func.__name__, result))
+            try:
+                result = func(*args, **kwargs)
+                logger.debug(
+                    "Done: {} with result: {}".format(func.__name__, result))
+            except BaseException as e:
+                tb = traceback.format_exc()
+                logger.error(
+                    '{func} raised: {exc!r}\n'
+                    'Traceback: {tb!s}'.format(
+                        func=func.__name__, exc=e, tb=tb))
+                raise
             return result
         return wrapped
     return wrapper

fuelweb_test/helpers/metaclasses.py

@@ -0,0 +1,27 @@
+#    Copyright 2016 Mirantis, Inc.
+#
+#    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.
+
+
+class SingletonMeta(type):
+    """Metaclass for Singleton
+
+    Main goals: not need to implement __new__ in singleton classes
+    """
+    _instances = {}
+
+    def __call__(cls, *args, **kwargs):
+        if cls not in cls._instances:
+            cls._instances[cls] = super(
+                SingletonMeta, cls).__call__(*args, **kwargs)
+        return cls._instances[cls]

fuelweb_test/helpers/ssh_manager.py

@@ -1,4 +1,4 @@
-#    Copyright 2015 Mirantis, Inc.
+#    Copyright 2016 Mirantis, Inc.
 #
 #    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
@@ -20,32 +20,27 @@ import json
 from paramiko import RSAKey
 from devops.models.node import SSHClient
 from fuelweb_test import logger
-
-
-class SingletonMeta(type):
-    def __init__(cls, name, bases, dict):
-        super(SingletonMeta, cls).__init__(name, bases, dict)
-        cls.instance = None
-
-    def __call__(self, *args, **kw):
-        if self.instance is None:
-            self.instance = super(SingletonMeta, self).__call__(*args, **kw)
-        return self.instance
-
-    def __getattr__(cls, name):
-        return getattr(cls(), name)
+from fuelweb_test.helpers import metaclasses
 
 
 class SSHManager(object):
-    __metaclass__ = SingletonMeta
+    __metaclass__ = metaclasses.SingletonMeta
+    # Slots is used to prevent uncontrolled attributes set or remove.
+    __slots__ = [
+        '__connections', 'admin_ip', 'admin_port', 'login', '__password'
+    ]
 
     def __init__(self):
         logger.debug('SSH_MANAGER: Run constructor SSHManager')
-        self.connections = {}
+        self.__connections = {}  # Disallow direct type change and deletion
         self.admin_ip = None
         self.admin_port = None
         self.login = None
-        self.password = None
+        self.__password = None
+
+    @property
+    def connections(self):
+        return self.__connections
 
     def initialize(self, admin_ip, login, password):
         """ It will be moved to __init__
@@ -58,7 +53,7 @@ class SSHManager(object):
         self.admin_ip = admin_ip
         self.admin_port = 22
         self.login = login
-        self.password = password
+        self.__password = password
 
     def _connect(self, remote):
         """ Check if connection is stable and return this one
@@ -97,7 +92,7 @@ class SSHManager(object):
                 host=ip,
                 port=port,
                 username=self.login,
-                password=self.password,
+                password=self.__password,
                 private_keys=keys
             )
         logger.debug('SSH_MANAGER:Return existed connection for '
@@ -192,6 +187,10 @@ class SSHManager(object):
 
         return result
 
+    def execute_async_on_remote(self, ip, cmd, port=22):
+        remote = self._get_remote(ip=ip, port=port)
+        return remote.execute_async(cmd)
+
     def _json_deserialize(self, json_string):
         """ Deserialize json_string and return object
 

fuelweb_test/models/environment.py

@@ -28,6 +28,7 @@ from proboscis.asserts import assert_true
 from fuelweb_test.helpers.decorators import revert_info
 from fuelweb_test.helpers.decorators import update_rpm_packages
 from fuelweb_test.helpers.decorators import upload_manifests
+from fuelweb_test.helpers.metaclasses import SingletonMeta
 from fuelweb_test.helpers.eb_tables import Ebtables
 from fuelweb_test.helpers.fuel_actions import AdminActions
 from fuelweb_test.helpers.fuel_actions import BaseActions
@@ -51,13 +52,7 @@ from fuelweb_test import logger
 class EnvironmentModel(object):
     """EnvironmentModel."""  # TODO documentation
 
-    _instance = None
-
-    def __new__(cls, *args, **kwargs):
-        if not cls._instance:
-            cls._instance = super(EnvironmentModel, cls).__new__(
-                cls, *args, **kwargs)
-        return cls._instance
+    __metaclass__ = SingletonMeta
 
     def __init__(self, config=None):
         if not hasattr(self, "_virt_env"):