Make method import_versioned_module work

We hard-code module name in method import_versioned_module,
but downstream projects can't work and must provide specific
version of this method[1], and we don't use it in any project,
so we don't need consider backwards compatible issue.

[1] http://codesearch.openstack.org/?q=import_versioned_module&i=nope&files=&repos=

Closes-Bug: #1627313
Change-Id: I9eac6e63283a6b3a364307b32c567d27e97bdb6e

oslo_utils/importutils.py

@@ -74,15 +74,27 @@ def import_module(import_str):
     return sys.modules[import_str]
 
 
-def import_versioned_module(version, submodule=None):
-    """Import a versioned module.
+def import_versioned_module(module, version, submodule=None):
+    """Import a versioned module in format {module}.v{version][.{submodule}].
+
+    :param module: the module name.
+    :param version: the version number.
+    :param submodule: the submodule name.
+    :raises ValueError: For any invalid input.
 
     .. versionadded:: 0.3
+
+    .. versionchanged:: 3.17
+       Added *module* parameter.
     """
-    module = 'oslo.v%s' % version
+
+    # NOTE(gcb) Disallow parameter version include character '.'
+    if '.' in '%s' % version:
+        raise ValueError("Parameter version shouldn't include character '.'.")
+    module_str = '%s.v%s' % (module, version)
     if submodule:
-        module = '.'.join((module, submodule))
-    return import_module(module)
+        module_str = '.'.join((module_str, submodule))
+    return import_module(module_str)
 
 
 def try_import(import_str, default=None):

oslo_utils/tests/fake/v2/dummpy.py

@@ -0,0 +1,28 @@
+# Copyright 2016, EasyStack, 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 V2FakeDriver(object):
+    def __init__(self, first_arg=True):
+        self.first_arg = first_arg
+
+
+class V2FakeDriver2(object):
+    def __init__(self, first_arg):
+        self.first_arg = first_arg
+
+
+class V2FakeDriver3(object):
+    def __init__(self):
+        raise ImportError("ImportError occurs in __init__")

oslo_utils/tests/test_importutils.py

@@ -116,6 +116,25 @@ class ImportUtilsTest(test_base.BaseTestCase):
         self.assertIsInstance(dt, sys.modules['datetime'].datetime)
         self.assertEqual(dt, datetime.datetime(2012, 4, 5))
 
+    def test_import_versioned_module(self):
+        v2 = importutils.import_versioned_module('oslo_utils.tests.fake', 2)
+        self.assertEqual(sys.modules['oslo_utils.tests.fake.v2'], v2)
+
+        dummpy = importutils.import_versioned_module('oslo_utils.tests.fake',
+                                                     2, 'dummpy')
+        self.assertEqual(sys.modules['oslo_utils.tests.fake.v2.dummpy'],
+                         dummpy)
+
+    def test_import_versioned_module_wrong_version_parameter(self):
+        self.assertRaises(ValueError,
+                          importutils.import_versioned_module,
+                          'oslo_utils.tests.fake', "2.0", 'fake')
+
+    def test_import_versioned_module_error(self):
+        self.assertRaises(ImportError,
+                          importutils.import_versioned_module,
+                          'oslo_utils.tests.fake', 2, 'fake')
+
     def test_try_import(self):
         dt = importutils.try_import('datetime')
         self.assertEqual(sys.modules['datetime'], dt)