Replace "oslo_utils.importutils" with standard library "importlib"

The current implementation of dynamic library importation is prone
to failure [1]:
- "sys.modules" is modified manually, which is something not
  recommended [2].
- When a module is imported is added to "sys.modules"; that means
  there is no need to manually create an entry in this object.
- "importlib" library is part of the standard library and is now
  available in PY3 and PY2 (backported). This library contains a
  function called "import_module" to import a module in runtime.

[1]https://github.com/opnfv/yardstick/blob/d2c7cc4e9768ed003257a95c92cdb278d516761b/yardstick/common/utils.py#L72-L93
[2]http://justus.science/blog/2015/04/19/sys.modules-is-dangerous.html

JIRA: YARDSTICK-949

Change-Id: Ide3b74f98858d06fa275fb6c9b78ceeaa64feed5
Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>

6 files changed, 73 insertions, 29 deletions

diff --git a/yardstick/common/utils.py b/yardstick/common/utils.py
index 82e20bec7..8604e900f 100644
--- a/yardstick/common/utils.py
+++ b/yardstick/common/utils.py
@@ -13,27 +13,22 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-# yardstick comment: this is a modified copy of rally/rally/common/utils.py
-
-from __future__ import absolute_import
-from __future__ import print_function
-
+import collections
+from contextlib import closing
 import datetime
 import errno
+import importlib
+import ipaddress
 import logging
 import os
+import random
+import socket
 import subprocess
 import sys
-import collections
-import socket
-import random
-import ipaddress
-from contextlib import closing
 
 import six
 from flask import jsonify
 from six.moves import configparser
-from oslo_utils import importutils
 from oslo_serialization import jsonutils
 
 import yardstick
@@ -70,27 +65,28 @@ def itersubclasses(cls, _seen=None):
 
 
 def import_modules_from_package(package):
-    """Import modules from package and append into sys.modules
+    """Import modules given a package name
 
     :param: package - Full package name. For example: rally.deploy.engines
     """
     yardstick_root = os.path.dirname(os.path.dirname(yardstick.__file__))
-    path = os.path.join(yardstick_root, *package.split("."))
+    path = os.path.join(yardstick_root, *package.split('.'))
     for root, _, files in os.walk(path):
-        matches = (filename for filename in files if filename.endswith(".py") and
-                   not filename.startswith("__"))
-        new_package = os.path.relpath(root, yardstick_root).replace(os.sep, ".")
+        matches = (filename for filename in files if filename.endswith('.py')
+                   and not filename.startswith('__'))
+        new_package = os.path.relpath(root, yardstick_root).replace(os.sep,
+                                                                    '.')
         module_names = set(
-            ("{}.{}".format(new_package, filename.rsplit(".py", 1)[0]) for filename in matches))
-        # find modules which haven't already been imported
+            '{}.{}'.format(new_package, filename.rsplit('.py', 1)[0])
+            for filename in matches)
+        # Find modules which haven't already been imported
         missing_modules = module_names.difference(sys.modules)
-        logger.debug("importing %s", missing_modules)
-        # we have already checked for already imported modules, so we don't need to check again
+        logger.debug('Importing modules: %s', missing_modules)
         for module_name in missing_modules:
             try:
-                sys.modules[module_name] = importutils.import_module(module_name)
+                importlib.import_module(module_name)
             except (ImportError, SyntaxError):
-                logger.exception("unable to import %s", module_name)
+                logger.exception('Unable to import module %s', module_name)
 
 
 def makedirs(d):
diff --git a/yardstick/tests/functional/common/__init__.py b/yardstick/tests/functional/common/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/yardstick/tests/functional/common/__init__.py
diff --git a/yardstick/tests/functional/common/fake_module/__init__.py b/yardstick/tests/functional/common/fake_module/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/yardstick/tests/functional/common/fake_module/__init__.py
diff --git a/yardstick/tests/functional/common/fake_module/fake_library.py b/yardstick/tests/functional/common/fake_module/fake_library.py
new file mode 100644
index 000000000..28c7dc694
--- /dev/null
+++ b/yardstick/tests/functional/common/fake_module/fake_library.py
@@ -0,0 +1,17 @@
+# 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.
+
+
+class FakeClassToBeImported(object):
+    pass
diff --git a/yardstick/tests/functional/common/test_utils.py b/yardstick/tests/functional/common/test_utils.py
new file mode 100644
index 000000000..b5333bbde
--- /dev/null
+++ b/yardstick/tests/functional/common/test_utils.py
@@ -0,0 +1,34 @@
+# 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 unittest
+import sys
+
+from yardstick.common import utils
+
+
+class ImportModulesFromPackageTestCase(unittest.TestCase):
+
+    def test_import_package(self):
+        module_name = 'yardstick.tests.functional.common.fake_module'
+        library_name = 'fake_library'
+        class_name = 'FakeClassToBeImported'
+        self.assertNotIn(module_name, sys.modules)
+
+        utils.import_modules_from_package(module_name)
+        self.assertIn(module_name, sys.modules)
+        module_obj = sys.modules[module_name]
+        library_obj = getattr(module_obj, library_name)
+        class_obj = getattr(library_obj, class_name)
+        self.assertEqual(class_name, class_obj().__class__.__name__)
diff --git a/yardstick/tests/unit/common/test_utils.py b/yardstick/tests/unit/common/test_utils.py
index 452b93a56..033bb0243 100644
--- a/yardstick/tests/unit/common/test_utils.py
+++ b/yardstick/tests/unit/common/test_utils.py
@@ -7,12 +7,9 @@
 # http://www.apache.org/licenses/LICENSE-2.0
 ##############################################################################
 
-# Unittest for yardstick.common.utils
-
-from __future__ import absolute_import
-
 from copy import deepcopy
 import errno
+import importlib
 import ipaddress
 from itertools import product, chain
 import mock
@@ -60,8 +57,8 @@ class ImportModulesFromPackageTestCase(unittest.TestCase):
         utils.import_modules_from_package('foo.bar')
 
     @mock.patch('yardstick.common.utils.os.walk')
-    @mock.patch('yardstick.common.utils.importutils')
-    def test_import_modules_from_package(self, mock_importutils, mock_walk):
+    @mock.patch.object(importlib, 'import_module')
+    def test_import_modules_from_package(self, mock_import_module, mock_walk):
 
         yardstick_root = os.path.dirname(os.path.dirname(yardstick.__file__))
         mock_walk.return_value = ([
@@ -69,7 +66,7 @@ class ImportModulesFromPackageTestCase(unittest.TestCase):
         ])
 
         utils.import_modules_from_package('foo.bar')
-        mock_importutils.import_module.assert_called_with('bar.baz')
+        mock_import_module.assert_called_once_with('bar.baz')
 
 
 class GetParaFromYaml(unittest.TestCase):