Fixing tests with tox 4.2.6

1. Remove basepython from testenv
2. this change also fix unittests because stevedore has dropped pkg_resources[0],
after tox upgraded to 4.0.*, tox with usedevelop parameter installs trove in
develop mode, hence stevedore unable to get the entrypoints from sdist[1].
[0]: d5297167e0
[1]: https://tox.wiki/en/2.8.1/config.html#confval-usedevelop=BOOL

Change-Id: Ie65d099509e3cb7a61a09d975c58c1e95aa12b51

tox.ini

@@ -4,7 +4,6 @@ minversion = 3.18.0
 skipsdist = True
 
 [testenv]
-basepython = python3
 setenv = VIRTUAL_ENV={envdir}
          PYTHONWARNINGS=default::DeprecationWarning
          OS_TEST_PATH=./trove/tests/unittests

trove/tests/unittests/api/common/test_extensions.py

@@ -15,9 +15,10 @@
 
 import configparser
 import os
-import pkg_resources
 from unittest import mock
 
+import importlib.metadata as importlib_metadata
+
 import trove
 from trove.common import extensions
 from trove.extensions.routes.mgmt import Mgmt
@@ -29,11 +30,12 @@ DEFAULT_EXTENSION_MAP = {
     'MYSQL': [Mysql, extensions.ExtensionDescriptor]
 }
 
-EP_TEXT = '''
-mgmt = trove.extensions.routes.mgmt:Mgmt
-mysql = trove.extensions.routes.mysql:Mysql
-invalid = trove.tests.unittests.api.common.test_extensions:InvalidExtension
-'''
+INVALID_EXTENSION_MAP = {
+    'mgmt': 'trove.extensions.routes.mgmt:Mgmt',
+    'mysql': 'trove.extensions.routes.mysql:Mysql',
+    'invalid': 'trove.tests.unittests.api.common.'
+               'test_extensions:InvalidExtension'
+}
 
 
 class InvalidExtension(object):
@@ -68,8 +70,8 @@ class TestExtensionLoading(trove_testtools.TestCase):
             for clazz in DEFAULT_EXTENSION_MAP[alias]:
                 self.assertIsInstance(ext, clazz, "Improper extension class")
 
-    @mock.patch("pkg_resources.iter_entry_points")
-    def test_default_extensions(self, mock_iter_eps):
+    @mock.patch("stevedore.enabled.EnabledExtensionManager.list_entry_points")
+    def test_default_extensions(self, mock_extensions):
         trove_base = os.path.abspath(os.path.join(
             os.path.dirname(trove.__file__), ".."))
         setup_path = "%s/setup.cfg" % trove_base
@@ -79,20 +81,31 @@ class TestExtensionLoading(trove_testtools.TestCase):
             parser.read(setup_path)
             entry_points = parser.get(
                 'entry_points', extensions.ExtensionManager.EXT_NAMESPACE)
-            eps = pkg_resources.EntryPoint.parse_group('plugins', entry_points)
-            mock_iter_eps.return_value = eps.values()
+            test_extensions = list()
+            for entry in entry_points.split('\n')[1:]:
+                name = entry.split("=")[0].strip()
+                value = entry.split("=")[1].strip()
+                test_extensions.append(importlib_metadata.EntryPoint(
+                    name=name,
+                    value=value,
+                    group=extensions.ExtensionManager.EXT_NAMESPACE))
+        mock_extensions.return_value = test_extensions
         extension_mgr = extensions.ExtensionManager()
         self.assertEqual(sorted(DEFAULT_EXTENSION_MAP.keys()),
                          sorted(extension_mgr.extensions.keys()),
                          "Invalid extension names")
         self._assert_default_extensions(extension_mgr.extensions)
 
-    @mock.patch("pkg_resources.iter_entry_points")
-    def test_invalid_extension(self, mock_iter_eps):
-        eps = pkg_resources.EntryPoint.parse_group('mock', EP_TEXT)
-        mock_iter_eps.return_value = eps.values()
+    @mock.patch("stevedore.enabled.EnabledExtensionManager.list_entry_points")
+    def test_invalid_extension(self, mock_extensions):
+        test_extensions = list()
+        for k, v in INVALID_EXTENSION_MAP.items():
+            test_extensions.append(importlib_metadata.EntryPoint(
+                name=k,
+                value=v,
+                group=extensions.ExtensionManager.EXT_NAMESPACE))
+        mock_extensions.return_value = test_extensions
         extension_mgr = extensions.ExtensionManager()
-        self.assertEqual(len(DEFAULT_EXTENSION_MAP.keys()),
-                         len(extension_mgr.extensions),
+        self.assertEqual(2, len(extension_mgr.extensions),
                          "Loaded invalid extensions")
         self._assert_default_extensions(extension_mgr.extensions)