Import "traffic_profile" modules only once

"traffic_profile" modules should be imported only once. Every time
TrafficProfile.get is called, the modules under
"yardstick.network_services.traffic_profiles" are loaded [1]. Instead
of this, the modules should be registered only once the first time
"yardstick.network_services.traffic_profiles.base" is loaded. This
will reduce the execution time and will avoid unnecessary calls.

[1] https://github.com/opnfv/yardstick/blob/d2c7cc4e9768ed003257a95c92cdb278d516761b/yardstick/network_services/traffic_profile/base.py#L36-L37

JIRA: YARDSTICK-951

Change-Id: Ia3565378ba3a1377fcb0aea8bda50ef8189414fd
Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>

15 files changed, 232 insertions, 174 deletions

diff --git a/yardstick/benchmark/scenarios/networking/vnf_generic.py b/yardstick/benchmark/scenarios/networking/vnf_generic.py
index b94bfc9ab..b81bac70b 100644
--- a/yardstick/benchmark/scenarios/networking/vnf_generic.py
+++ b/yardstick/benchmark/scenarios/networking/vnf_generic.py
@@ -11,38 +11,36 @@
 # 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.
-""" NSPerf specific scenario definition """
-
-from __future__ import absolute_import
 
+from collections import defaultdict
+import copy
 import logging
-import errno
-
 import ipaddress
-
-import copy
+from itertools import chain
 import os
-import sys
 import re
-from itertools import chain
+import sys
 
 import six
 import yaml
-from collections import defaultdict
 
-from yardstick.benchmark.scenarios import base
+from yardstick.benchmark.scenarios import base as scenario_base
 from yardstick.common.constants import LOG_DIR
 from yardstick.common.process import terminate_children
-from yardstick.common.utils import import_modules_from_package, itersubclasses
+from yardstick.common import utils
 from yardstick.common.yaml_loader import yaml_load
 from yardstick.network_services.collector.subscriber import Collector
 from yardstick.network_services.vnf_generic import vnfdgen
 from yardstick.network_services.vnf_generic.vnf.base import GenericVNF
-from yardstick.network_services.traffic_profile.base import TrafficProfile
+from yardstick.network_services import traffic_profile
+from yardstick.network_services.traffic_profile import base as tprofile_base
 from yardstick.network_services.utils import get_nsb_option
 from yardstick import ssh
 
 
+traffic_profile.register_modules()
+
+
 LOG = logging.getLogger(__name__)
 
 
@@ -91,35 +89,7 @@ class SshManager(object):
             self.conn.close()
 
 
-def find_relative_file(path, task_path):
-    """
-    Find file in one of places: in abs of path or
-    relative to TC scenario file. In this order.
-
-    :param path:
-    :param task_path:
-    :return str: full path to file
-    """
-    # fixme: create schema to validate all fields have been provided
-    for lookup in [os.path.abspath(path), os.path.join(task_path, path)]:
-        try:
-            with open(lookup):
-                return lookup
-        except IOError:
-            pass
-    raise IOError(errno.ENOENT, 'Unable to find {} file'.format(path))
-
-
-def open_relative_file(path, task_path):
-    try:
-        return open(path)
-    except IOError as e:
-        if e.errno == errno.ENOENT:
-            return open(os.path.join(task_path, path))
-        raise
-
-
-class NetworkServiceTestCase(base.Scenario):
+class NetworkServiceTestCase(scenario_base.Scenario):
     """Class handles Generic framework to do pre-deployment VNF &
        Network service testing  """
 
@@ -131,8 +101,8 @@ class NetworkServiceTestCase(base.Scenario):
         self.context_cfg = context_cfg
 
         # fixme: create schema to validate all fields have been provided
-        with open_relative_file(scenario_cfg["topology"],
-                                scenario_cfg['task_path']) as stream:
+        with utils.open_relative_file(scenario_cfg["topology"],
+                                      scenario_cfg['task_path']) as stream:
             topology_yaml = yaml_load(stream)
 
         self.topology = topology_yaml["nsd:nsd-catalog"]["nsd"][0]
@@ -211,7 +181,7 @@ class NetworkServiceTestCase(base.Scenario):
     def _get_traffic_profile(self):
         profile = self.scenario_cfg["traffic_profile"]
         path = self.scenario_cfg["task_path"]
-        with open_relative_file(profile, path) as infile:
+        with utils.open_relative_file(profile, path) as infile:
             return infile.read()
 
     def _fill_traffic_profile(self):
@@ -219,12 +189,12 @@ class NetworkServiceTestCase(base.Scenario):
         traffic_map_data = {
             'flow': self._get_traffic_flow(),
             'imix': self._get_traffic_imix(),
-            TrafficProfile.UPLINK: {},
-            TrafficProfile.DOWNLINK: {},
+            tprofile_base.TrafficProfile.UPLINK: {},
+            tprofile_base.TrafficProfile.DOWNLINK: {},
         }
 
         traffic_vnfd = vnfdgen.generate_vnfd(traffic_mapping, traffic_map_data)
-        self.traffic_profile = TrafficProfile.get(traffic_vnfd)
+        self.traffic_profile = tprofile_base.TrafficProfile.get(traffic_vnfd)
         return self.traffic_profile
 
     def _find_vnf_name_from_id(self, vnf_id):
@@ -451,12 +421,13 @@ class NetworkServiceTestCase(base.Scenario):
         self._resolve_topology()
         self._update_context_with_topology()
 
-    FIND_NETDEVICE_STRING = r"""find /sys/devices/pci* -type d -name net -exec sh -c '{ grep -sH ^ \
-$1/ifindex $1/address $1/operstate $1/device/vendor $1/device/device \
-$1/device/subsystem_vendor $1/device/subsystem_device ; \
-printf "%s/driver:" $1 ; basename $(readlink -s $1/device/driver); } \
-' sh  \{\}/* \;
-"""
+    FIND_NETDEVICE_STRING = (
+        r"""find /sys/devices/pci* -type d -name net -exec sh -c '{ grep -sH ^ \
+        $1/ifindex $1/address $1/operstate $1/device/vendor $1/device/device \
+        $1/device/subsystem_vendor $1/device/subsystem_device ; \
+        printf "%s/driver:" $1 ; basename $(readlink -s $1/device/driver); } \
+        ' sh  \{\}/* \;
+        """)
     BASE_ADAPTER_RE = re.compile(
         '^/sys/devices/(.*)/net/([^/]*)/([^:]*):(.*)$', re.M)
 
@@ -488,13 +459,14 @@ printf "%s/driver:" $1 ; basename $(readlink -s $1/device/driver); } \
         :param vnf_model_id: parsed vnfd model ID field
         :return: subclass of GenericVNF
         """
-        import_modules_from_package(
+        utils.import_modules_from_package(
             "yardstick.network_services.vnf_generic.vnf")
         expected_name = vnf_model_id
         classes_found = []
 
         def impl():
-            for name, class_ in ((c.__name__, c) for c in itersubclasses(GenericVNF)):
+            for name, class_ in ((c.__name__, c) for c in
+                                 utils.itersubclasses(GenericVNF)):
                 if name == expected_name:
                     yield class_
                 classes_found.append(name)
@@ -556,7 +528,7 @@ printf "%s/driver:" $1 ; basename $(readlink -s $1/device/driver); } \
                 LOG.debug("no model for %s, skipping", node_name)
                 continue
             file_path = scenario_cfg['task_path']
-            with open_relative_file(file_name, file_path) as stream:
+            with utils.open_relative_file(file_name, file_path) as stream:
                 vnf_model = stream.read()
             vnfd = vnfdgen.generate_vnfd(vnf_model, node)
             # TODO: here add extra context_cfg["nodes"] regardless of template
diff --git a/yardstick/common/exceptions.py b/yardstick/common/exceptions.py
index 3e0635e46..4562c4825 100644
--- a/yardstick/common/exceptions.py
+++ b/yardstick/common/exceptions.py
@@ -68,5 +68,10 @@ class HeatTemplateError(YardstickException):
 class IPv6RangeError(YardstickException):
     message = 'Start IP "%(start_ip)s" is greater than end IP "%(end_ip)s"'
 
+
+class TrafficProfileNotImplemented(YardstickException):
+    message = 'No implementation for traffic profile %(profile_class)s.'
+
+
 class DPDKSetupDriverError(YardstickException):
     message = '"igb_uio" driver is not loaded'
diff --git a/yardstick/common/utils.py b/yardstick/common/utils.py
index 495290122..621117f9c 100644
--- a/yardstick/common/utils.py
+++ b/yardstick/common/utils.py
@@ -65,7 +65,7 @@ def itersubclasses(cls, _seen=None):
                 yield sub
 
 
-def import_modules_from_package(package):
+def import_modules_from_package(package, raise_exception=False):
     """Import modules given a package name
 
     :param: package - Full package name. For example: rally.deploy.engines
@@ -86,7 +86,9 @@ def import_modules_from_package(package):
         for module_name in missing_modules:
             try:
                 importlib.import_module(module_name)
-            except (ImportError, SyntaxError):
+            except (ImportError, SyntaxError) as exc:
+                if raise_exception:
+                    raise exc
                 logger.exception('Unable to import module %s', module_name)
 
 
@@ -410,3 +412,31 @@ def read_meminfo(ssh_client):
         output[match[0]] = match[1]
 
     return output
+
+
+def find_relative_file(path, task_path):
+    """
+    Find file in one of places: in abs of path or relative to a directory path,
+    in this order.
+
+    :param path:
+    :param task_path:
+    :return str: full path to file
+    """
+    # fixme: create schema to validate all fields have been provided
+    for lookup in [os.path.abspath(path), os.path.join(task_path, path)]:
+        try:
+            with open(lookup):
+                return lookup
+        except IOError:
+            pass
+    raise IOError(errno.ENOENT, 'Unable to find {} file'.format(path))
+
+
+def open_relative_file(path, task_path):
+    try:
+        return open(path)
+    except IOError as e:
+        if e.errno == errno.ENOENT:
+            return open(os.path.join(task_path, path))
+        raise
diff --git a/yardstick/network_services/traffic_profile/__init__.py b/yardstick/network_services/traffic_profile/__init__.py
index e69de29bb..356b36bd9 100644
--- a/yardstick/network_services/traffic_profile/__init__.py
+++ b/yardstick/network_services/traffic_profile/__init__.py
@@ -0,0 +1,33 @@
+# Copyright (c) 2018 Intel Corporation
+#
+# 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 importlib
+
+
+def register_modules():
+    modules = [
+        'yardstick.network_services.traffic_profile.trex_traffic_profile',
+        'yardstick.network_services.traffic_profile.fixed',
+        'yardstick.network_services.traffic_profile.http',
+        'yardstick.network_services.traffic_profile.http_ixload',
+        'yardstick.network_services.traffic_profile.ixia_rfc2544',
+        'yardstick.network_services.traffic_profile.prox_ACL',
+        'yardstick.network_services.traffic_profile.prox_binsearch',
+        'yardstick.network_services.traffic_profile.prox_profile',
+        'yardstick.network_services.traffic_profile.prox_ramp',
+        'yardstick.network_services.traffic_profile.rfc2544',
+    ]
+
+    for module in modules:
+        importlib.import_module(module)
diff --git a/yardstick/network_services/traffic_profile/base.py b/yardstick/network_services/traffic_profile/base.py
index ad256b444..162bab2bc 100644
--- a/yardstick/network_services/traffic_profile/base.py
+++ b/yardstick/network_services/traffic_profile/base.py
@@ -11,10 +11,9 @@
 # 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.
-""" Base class for the generic traffic profile implementation """
 
-from __future__ import absolute_import
-from yardstick.common.utils import import_modules_from_package, itersubclasses
+from yardstick.common import exceptions
+from yardstick.common import utils
 
 
 class TrafficProfile(object):
@@ -33,13 +32,12 @@ class TrafficProfile(object):
         :return:
         """
         profile_class = tp_config["traffic_profile"]["traffic_type"]
-        import_modules_from_package(
-            "yardstick.network_services.traffic_profile")
         try:
-            return next(c for c in itersubclasses(TrafficProfile)
+            return next(c for c in utils.itersubclasses(TrafficProfile)
                         if c.__name__ == profile_class)(tp_config)
         except StopIteration:
-            raise RuntimeError("No implementation for %s", profile_class)
+            raise exceptions.TrafficProfileNotImplemented(
+                profile_class=profile_class)
 
     def __init__(self, tp_config):
         # e.g. RFC2544 start_ip, stop_ip, drop_rate,
diff --git a/yardstick/network_services/traffic_profile/trex_traffic_profile.py b/yardstick/network_services/traffic_profile/trex_traffic_profile.py
index 8cde5e4a7..f5e3923d5 100644
--- a/yardstick/network_services/traffic_profile/trex_traffic_profile.py
+++ b/yardstick/network_services/traffic_profile/trex_traffic_profile.py
@@ -21,7 +21,7 @@ import ipaddress
 import six
 
 from yardstick.common import exceptions as y_exc
-from yardstick.network_services.traffic_profile.base import TrafficProfile
+from yardstick.network_services.traffic_profile import base
 from trex_stl_lib.trex_stl_client import STLStream
 from trex_stl_lib.trex_stl_streams import STLFlowLatencyStats
 from trex_stl_lib.trex_stl_streams import STLTXCont
@@ -48,7 +48,7 @@ TYPE_OF_SERVICE = 'tos'
 LOG = logging.getLogger(__name__)
 
 
-class TrexProfile(TrafficProfile):
+class TrexProfile(base.TrafficProfile):
     """ This class handles Trex Traffic profile generation and execution """
 
     PROTO_MAP = {
@@ -127,7 +127,7 @@ class TrexProfile(TrafficProfile):
             self.vm_flow_vars.append(stl_vm_wr_flow_var)
         return partial
 
-    def _dscp_range_action_partial(self, *_):
+    def _dscp_range_action_partial(self, *args):
         def partial(min_value, max_value, count):
             # pylint: disable=unused-argument
             stl_vm_flow_var = STLVmFlowVar(name="dscp",
diff --git a/yardstick/network_services/vnf_generic/vnf/acl_vnf.py b/yardstick/network_services/vnf_generic/vnf/acl_vnf.py
index 1390dd02e..f3cafef7a 100644
--- a/yardstick/network_services/vnf_generic/vnf/acl_vnf.py
+++ b/yardstick/network_services/vnf_generic/vnf/acl_vnf.py
@@ -12,11 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import absolute_import
-from __future__ import print_function
 import logging
 
-from yardstick.benchmark.scenarios.networking.vnf_generic import find_relative_file
+from yardstick.common import utils
 from yardstick.network_services.vnf_generic.vnf.sample_vnf import SampleVNF, DpdkVnfSetupEnvHelper
 from yardstick.network_services.yang_model import YangModel
 
@@ -62,8 +60,9 @@ class AclApproxVnf(SampleVNF):
         self.acl_rules = None
 
     def _start_vnf(self):
-        yang_model_path = find_relative_file(self.scenario_helper.options['rules'],
-                                             self.scenario_helper.task_path)
+        yang_model_path = utils.find_relative_file(
+            self.scenario_helper.options['rules'],
+            self.scenario_helper.task_path)
         yang_model = YangModel(yang_model_path)
         self.acl_rules = yang_model.get_rules()
         super(AclApproxVnf, self)._start_vnf()
diff --git a/yardstick/network_services/vnf_generic/vnf/prox_helpers.py b/yardstick/network_services/vnf_generic/vnf/prox_helpers.py
index 61775b963..29f9c7bba 100644
--- a/yardstick/network_services/vnf_generic/vnf/prox_helpers.py
+++ b/yardstick/network_services/vnf_generic/vnf/prox_helpers.py
@@ -30,7 +30,6 @@ import six
 from six.moves import cStringIO
 from six.moves import zip, StringIO
 
-from yardstick.benchmark.scenarios.networking.vnf_generic import find_relative_file
 from yardstick.common import utils
 from yardstick.common.utils import SocketTopology, join_non_strings, try_int
 from yardstick.network_services.helpers.iniparser import ConfigParser
@@ -798,7 +797,7 @@ class ProxDpdkVnfSetupEnvHelper(DpdkVnfSetupEnvHelper):
         options = self.scenario_helper.options
         config_path = options['prox_config']
         config_file = os.path.basename(config_path)
-        config_path = find_relative_file(config_path, task_path)
+        config_path = utils.find_relative_file(config_path, task_path)
         self.additional_files = {}
 
         try:
@@ -815,7 +814,7 @@ class ProxDpdkVnfSetupEnvHelper(DpdkVnfSetupEnvHelper):
             prox_files = [prox_files]
         for key_prox_file in prox_files:
             base_prox_file = os.path.basename(key_prox_file)
-            key_prox_path = find_relative_file(key_prox_file, task_path)
+            key_prox_path = utils.find_relative_file(key_prox_file, task_path)
             remote_prox_file = self.copy_to_target(key_prox_path, base_prox_file)
             self.additional_files[base_prox_file] = remote_prox_file
 
diff --git a/yardstick/network_services/vnf_generic/vnf/sample_vnf.py b/yardstick/network_services/vnf_generic/vnf/sample_vnf.py
index 200930322..a6b1d0792 100644
--- a/yardstick/network_services/vnf_generic/vnf/sample_vnf.py
+++ b/yardstick/network_services/vnf_generic/vnf/sample_vnf.py
@@ -29,10 +29,9 @@ from trex_stl_lib.trex_stl_client import LoggerApi
 from trex_stl_lib.trex_stl_client import STLClient
 from trex_stl_lib.trex_stl_exceptions import STLError
 from yardstick.benchmark.contexts.base import Context
-from yardstick.benchmark.scenarios.networking.vnf_generic import find_relative_file
 from yardstick.common import exceptions as y_exceptions
-from yardstick.common import utils
 from yardstick.common.process import check_if_process_failed
+from yardstick.common import utils
 from yardstick.network_services.helpers.dpdkbindnic_helper import DpdkBindHelper
 from yardstick.network_services.helpers.samplevnf_helper import PortPairs
 from yardstick.network_services.helpers.samplevnf_helper import MultiPortConfig
@@ -187,7 +186,8 @@ class DpdkVnfSetupEnvHelper(SetupEnvHelper):
             'vnf_type': self.VNF_TYPE,
         }
 
-        config_tpl_cfg = find_relative_file(self.DEFAULT_CONFIG_TPL_CFG, task_path)
+        config_tpl_cfg = utils.find_relative_file(self.DEFAULT_CONFIG_TPL_CFG,
+                                                  task_path)
         config_basename = posixpath.basename(self.CFG_CONFIG)
         script_basename = posixpath.basename(self.CFG_SCRIPT)
         multiport = MultiPortConfig(self.scenario_helper.topology,
diff --git a/yardstick/network_services/vnf_generic/vnf/tg_ixload.py b/yardstick/network_services/vnf_generic/vnf/tg_ixload.py
index 3ab30b53e..02e7803f7 100644
--- a/yardstick/network_services/vnf_generic/vnf/tg_ixload.py
+++ b/yardstick/network_services/vnf_generic/vnf/tg_ixload.py
@@ -22,10 +22,10 @@ import shutil
 from collections import OrderedDict
 from subprocess import call
 
-from yardstick.common.utils import makedirs
+from yardstick.common import utils
 from yardstick.network_services.vnf_generic.vnf.sample_vnf import SampleVNFTrafficGen
 from yardstick.network_services.vnf_generic.vnf.sample_vnf import ClientResourceHelper
-from yardstick.benchmark.scenarios.networking.vnf_generic import find_relative_file
+
 
 LOG = logging.getLogger(__name__)
 
@@ -93,9 +93,10 @@ class IxLoadResourceHelper(ClientResourceHelper):
     def setup(self):
         # NOTE: fixup scenario_helper to hanlde ixia
         self.resource_file_name = \
-            find_relative_file(self.scenario_helper.scenario_cfg['ixia_profile'],
-                               self.scenario_helper.scenario_cfg["task_path"])
-        makedirs(self.RESULTS_MOUNT)
+            utils.find_relative_file(
+                self.scenario_helper.scenario_cfg['ixia_profile'],
+                self.scenario_helper.scenario_cfg["task_path"])
+        utils.makedirs(self.RESULTS_MOUNT)
         cmd = MOUNT_CMD.format(self.vnfd_helper.mgmt_interface, self)
         LOG.debug(cmd)
 
@@ -103,7 +104,7 @@ class IxLoadResourceHelper(ClientResourceHelper):
             call(cmd, shell=True)
 
         shutil.rmtree(self.RESULTS_MOUNT, ignore_errors=True)
-        makedirs(self.RESULTS_MOUNT)
+        utils.makedirs(self.RESULTS_MOUNT)
         shutil.copy(self.resource_file_name, self.RESULTS_MOUNT)
 
     def make_aggregates(self):
diff --git a/yardstick/network_services/vnf_generic/vnf/tg_rfc2544_ixia.py b/yardstick/network_services/vnf_generic/vnf/tg_rfc2544_ixia.py
index 12510db96..068b19d8d 100644
--- a/yardstick/network_services/vnf_generic/vnf/tg_rfc2544_ixia.py
+++ b/yardstick/network_services/vnf_generic/vnf/tg_rfc2544_ixia.py
@@ -19,11 +19,11 @@ import os
 import logging
 import sys
 
-from yardstick.common.utils import ErrorClass
+from yardstick.common import utils
 from yardstick.network_services.vnf_generic.vnf.sample_vnf import SampleVNFTrafficGen
 from yardstick.network_services.vnf_generic.vnf.sample_vnf import ClientResourceHelper
 from yardstick.network_services.vnf_generic.vnf.sample_vnf import Rfc2544ResourceHelper
-from yardstick.benchmark.scenarios.networking.vnf_generic import find_relative_file
+
 
 LOG = logging.getLogger(__name__)
 
@@ -36,7 +36,7 @@ sys.path.append(IXNET_LIB)
 try:
     from IxNet import IxNextgen
 except ImportError:
-    IxNextgen = ErrorClass
+    IxNextgen = utils.ErrorClass
 
 
 class IxiaRfc2544Helper(Rfc2544ResourceHelper):
@@ -122,8 +122,9 @@ class IxiaResourceHelper(ClientResourceHelper):
 
         # we don't know client_file_name until runtime as instantiate
         client_file_name = \
-            find_relative_file(self.scenario_helper.scenario_cfg['ixia_profile'],
-                               self.scenario_helper.scenario_cfg["task_path"])
+            utils.find_relative_file(
+                self.scenario_helper.scenario_cfg['ixia_profile'],
+                self.scenario_helper.scenario_cfg["task_path"])
         self.client.ix_load_config(client_file_name)
         time.sleep(WAIT_AFTER_CFG_LOAD)
 
diff --git a/yardstick/network_services/vnf_generic/vnf/vfw_vnf.py b/yardstick/network_services/vnf_generic/vnf/vfw_vnf.py
index 6c95648ce..61e99855f 100644
--- a/yardstick/network_services/vnf_generic/vnf/vfw_vnf.py
+++ b/yardstick/network_services/vnf_generic/vnf/vfw_vnf.py
@@ -12,10 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import absolute_import
 import logging
 
-from yardstick.benchmark.scenarios.networking.vnf_generic import find_relative_file
+from yardstick.common import utils
 from yardstick.network_services.vnf_generic.vnf.sample_vnf import SampleVNF, DpdkVnfSetupEnvHelper
 from yardstick.network_services.yang_model import YangModel
 
@@ -60,8 +59,9 @@ class FWApproxVnf(SampleVNF):
         self.vfw_rules = None
 
     def _start_vnf(self):
-        yang_model_path = find_relative_file(self.scenario_helper.options['rules'],
-                                             self.scenario_helper.task_path)
+        yang_model_path = utils.find_relative_file(
+            self.scenario_helper.options['rules'],
+            self.scenario_helper.task_path)
         yang_model = YangModel(yang_model_path)
         self.vfw_rules = yang_model.get_rules()
         super(FWApproxVnf, self)._start_vnf()
diff --git a/yardstick/tests/unit/base.py b/yardstick/tests/unit/base.py
new file mode 100644
index 000000000..b943efc2b
--- /dev/null
+++ b/yardstick/tests/unit/base.py
@@ -0,0 +1,23 @@
+# Copyright 2018 Intel Corporation.
+#
+# 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 abc
+
+import six
+import unittest
+
+
+@six.add_metaclass(abc.ABCMeta)
+class BaseUnitTestCase(unittest.TestCase):
+    """Base class for unit tests"""
diff --git a/yardstick/tests/unit/benchmark/scenarios/networking/test_vnf_generic.py b/yardstick/tests/unit/benchmark/scenarios/networking/test_vnf_generic.py
index 64436eb4e..846de13de 100644
--- a/yardstick/tests/unit/benchmark/scenarios/networking/test_vnf_generic.py
+++ b/yardstick/tests/unit/benchmark/scenarios/networking/test_vnf_generic.py
@@ -11,18 +11,17 @@
 # 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 os
+from copy import deepcopy
 import errno
-import unittest
-import mock
+import os
 
-from copy import deepcopy
+import mock
+import six
+import unittest
 
-from yardstick.benchmark.scenarios.networking.vnf_generic import \
-    SshManager, NetworkServiceTestCase, IncorrectConfig, \
-    open_relative_file
+from yardstick.common import utils
+from yardstick.benchmark.scenarios.networking import vnf_generic
 from yardstick.network_services.collector.subscriber import Collector
 from yardstick.network_services.vnf_generic.vnf.base import \
     GenericTrafficGen, GenericVNF
@@ -334,7 +333,8 @@ class TestNetworkServiceTestCase(unittest.TestCase):
             },
         }
 
-        self.s = NetworkServiceTestCase(self.scenario_cfg, self.context_cfg)
+        self.s = vnf_generic.NetworkServiceTestCase(self.scenario_cfg,
+                                                    self.context_cfg)
 
     def _get_file_abspath(self, filename):
         curr_path = os.path.dirname(os.path.abspath(__file__))
@@ -347,8 +347,8 @@ class TestNetworkServiceTestCase(unittest.TestCase):
             ssh_mock.execute = \
                 mock.Mock(return_value=(0, SYS_CLASS_NET + IP_ADDR_SHOW, ""))
             ssh.from_node.return_value = ssh_mock
-            for _, node_dict in self.context_cfg["nodes"].items():
-                with SshManager(node_dict) as conn:
+            for node_dict in self.context_cfg["nodes"].values():
+                with vnf_generic.SshManager(node_dict) as conn:
                     self.assertIsNotNone(conn)
 
     def test___init__(self):
@@ -405,6 +405,10 @@ class TestNetworkServiceTestCase(unittest.TestCase):
             },
         }
 
+        # NOTE(ralonsoh): this variable is not used in the test case and maybe
+        # it should.
+        #result = {'flow': {'dst_ip0': '152.16.40.2-152.16.40.254',
+        #                   'src_ip0': '152.16.100.2-152.16.100.254'}}
         self.assertEqual({'flow': {}}, self.s._get_traffic_flow())
 
     def test___get_traffic_flow_error(self):
@@ -416,7 +420,7 @@ class TestNetworkServiceTestCase(unittest.TestCase):
         vnfd = COMPLETE_TREX_VNFD['vnfd:vnfd-catalog']['vnfd'][0]['class-name']
         self.assertIsNotNone(self.s.get_vnf_impl(vnfd))
 
-        with self.assertRaises(IncorrectConfig) as raised:
+        with self.assertRaises(vnf_generic.IncorrectConfig) as raised:
             self.s.get_vnf_impl('NonExistentClass')
 
         exc_str = str(raised.exception)
@@ -465,7 +469,7 @@ class TestNetworkServiceTestCase(unittest.TestCase):
                 mock.Mock(return_value=(1, SYS_CLASS_NET + IP_ADDR_SHOW, ""))
             ssh.from_node.return_value = ssh_mock
 
-            with self.assertRaises(IncorrectConfig):
+            with self.assertRaises(vnf_generic.IncorrectConfig):
                 self.s.map_topology_to_infrastructure()
 
     def test_map_topology_to_infrastructure_config_invalid(self):
@@ -477,7 +481,7 @@ class TestNetworkServiceTestCase(unittest.TestCase):
                 mock.Mock(return_value=(0, SYS_CLASS_NET + IP_ADDR_SHOW, ""))
             ssh.from_node.return_value = ssh_mock
 
-            with self.assertRaises(IncorrectConfig):
+            with self.assertRaises(vnf_generic.IncorrectConfig):
                 self.s.map_topology_to_infrastructure()
 
     def test__resolve_topology_invalid_config(self):
@@ -492,8 +496,8 @@ class TestNetworkServiceTestCase(unittest.TestCase):
                 del interface['local_mac']
 
             with mock.patch(
-                    "yardstick.benchmark.scenarios.networking.vnf_generic.LOG"):
-                with self.assertRaises(IncorrectConfig) as raised:
+                "yardstick.benchmark.scenarios.networking.vnf_generic.LOG"):
+                with self.assertRaises(vnf_generic.IncorrectConfig) as raised:
                     self.s._resolve_topology()
 
             self.assertIn('not found', str(raised.exception))
@@ -506,9 +510,8 @@ class TestNetworkServiceTestCase(unittest.TestCase):
             self.s.topology["vld"][0]['vnfd-connection-point-ref'].append(
                 self.s.topology["vld"][0]['vnfd-connection-point-ref'][0])
 
-            with mock.patch(
-                    "yardstick.benchmark.scenarios.networking.vnf_generic.LOG"):
-                with self.assertRaises(IncorrectConfig) as raised:
+            with mock.patch.object(vnf_generic, 'LOG'):
+                with self.assertRaises(vnf_generic.IncorrectConfig) as raised:
                     self.s._resolve_topology()
 
             self.assertIn('wrong endpoint count', str(raised.exception))
@@ -517,9 +520,8 @@ class TestNetworkServiceTestCase(unittest.TestCase):
             self.s.topology["vld"][0]['vnfd-connection-point-ref'] = \
                 self.s.topology["vld"][0]['vnfd-connection-point-ref'][:1]
 
-            with mock.patch(
-                    "yardstick.benchmark.scenarios.networking.vnf_generic.LOG"):
-                with self.assertRaises(IncorrectConfig) as raised:
+            with mock.patch.object(vnf_generic, 'LOG'):
+                with self.assertRaises(vnf_generic.IncorrectConfig) as raised:
                     self.s._resolve_topology()
 
             self.assertIn('wrong endpoint count', str(raised.exception))
@@ -707,7 +709,7 @@ class TestNetworkServiceTestCase(unittest.TestCase):
 /sys/devices/pci0000:00/0000:00:19.0/net/lan/driver:e1000e
 /sys/devices/pci0000:00/0000:00:19.0/net/lan/pci_bus_id:0000:00:19.0
 """
-        res = NetworkServiceTestCase.parse_netdev_info(output)
+        res = vnf_generic.NetworkServiceTestCase.parse_netdev_info(output)
         assert res == self.SAMPLE_NETDEVS
 
     def test_parse_netdev_info_virtio(self):
@@ -719,67 +721,63 @@ class TestNetworkServiceTestCase(unittest.TestCase):
 /sys/devices/pci0000:00/0000:00:04.0/virtio1/net/eth1/device/device:0x0001
 /sys/devices/pci0000:00/0000:00:04.0/virtio1/net/eth1/driver:virtio_net
 """
-        res = NetworkServiceTestCase.parse_netdev_info(output)
+        res = vnf_generic.NetworkServiceTestCase.parse_netdev_info(output)
         assert res == self.SAMPLE_VM_NETDEVS
 
     def test_probe_missing_values(self):
         netdevs = self.SAMPLE_NETDEVS.copy()
         network = {'local_mac': '0a:de:ad:be:ef:f5'}
-        NetworkServiceTestCase._probe_missing_values(netdevs, network)
+        vnf_generic.NetworkServiceTestCase._probe_missing_values(netdevs,
+                                                                 network)
         assert network['vpci'] == '0000:0b:00.0'
 
         network = {'local_mac': '0a:de:ad:be:ef:f4'}
-        NetworkServiceTestCase._probe_missing_values(netdevs, network)
+        vnf_generic.NetworkServiceTestCase._probe_missing_values(netdevs,
+                                                                 network)
         assert network['vpci'] == '0000:00:19.0'
 
-    # TODO: Split this into several tests, for different IOError sub-types
-    def test_open_relative_path(self):
-        mock_open = mock.mock_open()
+    @mock.patch.object(six.moves.builtins, 'open')
+    def test_open_relative_path(self, mock_open):
+        # NOTE(ralonsoh): the mocked function is not properly used and tested.
         mock_open_result = mock_open()
         mock_open_call_count = 1  # initial call to get result
-
-        module_name = \
-            'yardstick.benchmark.scenarios.networking.vnf_generic.open'
-
-        # test
-        with mock.patch(module_name, mock_open, create=True):
-            self.assertEqual(open_relative_file(
-                'foo', 'bar'), mock_open_result)
-
-            mock_open_call_count += 1  # one more call expected
-            self.assertEqual(mock_open.call_count, mock_open_call_count)
-            self.assertIn('foo', mock_open.call_args_list[-1][0][0])
-            self.assertNotIn('bar', mock_open.call_args_list[-1][0][0])
-
-            def open_effect(*args, **kwargs):
-                if kwargs.get('name', args[0]) == os.path.join('bar', 'foo'):
-                    return mock_open_result
-                raise IOError(errno.ENOENT, 'not found')
-
-            mock_open.side_effect = open_effect
-            self.assertEqual(open_relative_file(
-                'foo', 'bar'), mock_open_result)
-
-            mock_open_call_count += 2  # two more calls expected
-            self.assertEqual(mock_open.call_count, mock_open_call_count)
-            self.assertIn('foo', mock_open.call_args_list[-1][0][0])
-            self.assertIn('bar', mock_open.call_args_list[-1][0][0])
-
-            # test an IOError of type ENOENT
-            mock_open.side_effect = IOError(errno.ENOENT, 'not found')
-            with self.assertRaises(IOError):
-                # the second call still raises
-                open_relative_file('foo', 'bar')
-
-            mock_open_call_count += 2  # two more calls expected
-            self.assertEqual(mock_open.call_count, mock_open_call_count)
-            self.assertIn('foo', mock_open.call_args_list[-1][0][0])
-            self.assertIn('bar', mock_open.call_args_list[-1][0][0])
-
-            # test an IOError other than ENOENT
-            mock_open.side_effect = IOError(errno.EBUSY, 'busy')
-            with self.assertRaises(IOError):
-                open_relative_file('foo', 'bar')
-
-            mock_open_call_count += 1  # one more call expected
-            self.assertEqual(mock_open.call_count, mock_open_call_count)
+        self.assertEqual(utils.open_relative_file('foo', 'bar'),
+                         mock_open_result)
+
+        mock_open_call_count += 1  # one more call expected
+        self.assertEqual(mock_open.call_count, mock_open_call_count)
+        self.assertIn('foo', mock_open.call_args_list[-1][0][0])
+        self.assertNotIn('bar', mock_open.call_args_list[-1][0][0])
+
+        def open_effect(*args, **kwargs):
+            if kwargs.get('name', args[0]) == os.path.join('bar', 'foo'):
+                return mock_open_result
+            raise IOError(errno.ENOENT, 'not found')
+
+        mock_open.side_effect = open_effect
+        self.assertEqual(utils.open_relative_file('foo', 'bar'),
+                         mock_open_result)
+
+        mock_open_call_count += 2  # two more calls expected
+        self.assertEqual(mock_open.call_count, mock_open_call_count)
+        self.assertIn('foo', mock_open.call_args_list[-1][0][0])
+        self.assertIn('bar', mock_open.call_args_list[-1][0][0])
+
+        # test an IOError of type ENOENT
+        mock_open.side_effect = IOError(errno.ENOENT, 'not found')
+        with self.assertRaises(IOError):
+            # the second call still raises
+            utils.open_relative_file('foo', 'bar')
+
+        mock_open_call_count += 2  # two more calls expected
+        self.assertEqual(mock_open.call_count, mock_open_call_count)
+        self.assertIn('foo', mock_open.call_args_list[-1][0][0])
+        self.assertIn('bar', mock_open.call_args_list[-1][0][0])
+
+        # test an IOError other than ENOENT
+        mock_open.side_effect = IOError(errno.EBUSY, 'busy')
+        with self.assertRaises(IOError):
+            utils.open_relative_file('foo', 'bar')
+
+        mock_open_call_count += 1  # one more call expected
+        self.assertEqual(mock_open.call_count, mock_open_call_count)
diff --git a/yardstick/tests/unit/benchmark/scenarios/test_base.py b/yardstick/tests/unit/benchmark/scenarios/test_base.py
index a95e6bc86..985338532 100644
--- a/yardstick/tests/unit/benchmark/scenarios/test_base.py
+++ b/yardstick/tests/unit/benchmark/scenarios/test_base.py
@@ -13,12 +13,11 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import unittest
-
 from yardstick.benchmark.scenarios import base
+from yardstick.tests.unit import base as ut_base
 
 
-class ScenarioTestCase(unittest.TestCase):
+class ScenarioTestCase(ut_base.BaseUnitTestCase):
 
     def test_get_scenario_type(self):
         scenario_type = 'dummy scenario'
@@ -87,7 +86,7 @@ class ScenarioTestCase(unittest.TestCase):
                          str(exc.exception))
 
 
-class IterScenarioClassesTestCase(unittest.TestCase):
+class IterScenarioClassesTestCase(ut_base.BaseUnitTestCase):
 
     def test_no_scenario_type_defined(self):
         some_existing_scenario_class_names = [