Merge "A DisableModules fixture that removes modules from path"

oslotest/modules.py

@@ -0,0 +1,50 @@
+# 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 sys
+
+import fixtures
+
+
+class DisableModuleFixture(fixtures.Fixture):
+    """A fixture to provide support for unloading/disabling modules."""
+
+    def __init__(self, module, *args, **kwargs):
+        super(DisableModuleFixture, self).__init__(*args, **kwargs)
+        self.module = module
+
+    def setUp(self):
+        """Ensure ImportError for the specified module."""
+        super(DisableModuleFixture, self).setUp()
+
+        cleared_modules = {}
+
+        for name in list(sys.modules.keys()):
+            if name == self.module or name.startswith(self.module + '.'):
+                cleared_modules[name] = sys.modules.pop(name)
+
+        finder = _NoModuleFinder(self.module)
+        sys.meta_path.insert(0, finder)
+
+        self.addCleanup(sys.meta_path.remove, finder)
+        self.addCleanup(sys.modules.update, cleared_modules)
+
+
+class _NoModuleFinder(object):
+    """Disallow further imports of 'module'."""
+
+    def __init__(self, module):
+        self.module = module
+
+    def find_module(self, fullname, path):
+        if fullname == self.module or fullname.startswith(self.module + '.'):
+            raise ImportError

oslotest/tests/unit/test_modules.py

@@ -0,0 +1,28 @@
+# 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.
+
+from oslotest import base
+from oslotest import modules
+
+
+class CreateDisableModuleTest(base.BaseTestCase):
+
+    def test_disable_module(self):
+
+        s = __import__('sys')
+        self.assertTrue(s)
+
+        with modules.DisableModuleFixture('sys'):
+            self.assertRaises(ImportError, __import__, 'sys')
+
+        s = __import__('sys')
+        self.assertTrue(s)