1 files changed, 79 insertions, 0 deletions
diff --git a/fixtures/_fixtures/monkeypatch.py b/fixtures/_fixtures/monkeypatch.py
new file mode 100644
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+++ b/fixtures/_fixtures/monkeypatch.py
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+#  fixtures: Fixtures with cleanups for testing and convenience.
+#
+# Copyright (c) 2010, Robert Collins <robertc@robertcollins.net>
+# 
+# Licensed under either the Apache License, Version 2.0 or the BSD 3-clause
+# license at the users choice. A copy of both licenses are available in the
+# project source as Apache-2.0 and BSD. You may not use this file except in
+# compliance with one of these two licences.
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under these licenses is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# license you chose for the specific language governing permissions and
+# limitations under that license.
+
+__all__ = [
+    'MonkeyPatch'
+    ]
+
+import sys
+import types
+
+from fixtures import Fixture
+
+
+class MonkeyPatch(Fixture):
+    """Replace or delete an attribute."""
+
+    delete = object()
+
+    def __init__(self, name, new_value=None):
+        """Create a MonkeyPatch.
+
+        :param name: The fully qualified object name to override.
+        :param new_value: A value to set the name to. If set to
+            MonkeyPatch.delete the attribute will be deleted.
+
+        During setup the name will be deleted or assigned the requested value,
+        and this will be restored in cleanUp.
+        """
+        Fixture.__init__(self)
+        self.name = name
+        self.new_value = new_value
+    
+    def setUp(self):
+        Fixture.setUp(self)
+        location, attribute = self.name.rsplit('.', 1)
+        # Import, swallowing all errors as any element of location may be
+        # a class or some such thing.
+        try:
+            __import__(location, {}, {})
+        except ImportError:
+            pass
+        components = location.split('.')
+        current = __import__(components[0], {}, {})
+        for component in components[1:]:
+            current = getattr(current, component)
+        sentinel = object()
+        old_value = getattr(current, attribute, sentinel)
+        if self.new_value is self.delete:
+            if old_value is not sentinel:
+                delattr(current, attribute)
+        else:
+            setattr(current, attribute, self.new_value)
+        if old_value is sentinel:
+            self.addCleanup(self._safe_delete, current, attribute)
+        else:
+            # Python 2's setattr transforms function into instancemethod
+            if (sys.version_info[0] == 2 and
+                isinstance(current, (type, types.ClassType)) and
+                isinstance(old_value, types.FunctionType)):
+                    old_value = staticmethod(old_value)
+            self.addCleanup(setattr, current, attribute, old_value)
+
+    def _safe_delete(self, obj, attribute):
+        """Delete obj.attribute handling the case where its missing."""
+        sentinel = object()
+        if getattr(obj, attribute, sentinel) is not sentinel:
+            delattr(obj, attribute)