Adds invalidate method to MemCacheMapping

CHANGES.rst

@@ -4,6 +4,7 @@ Change log
 4.1 (unreleased)
 ----------------
 
+- Adds invalidate method to MemCacheMapping and test
 
 4.0 (2023-02-02)
 ----------------

src/Products/mcdutils/mapping.py

@@ -106,6 +106,16 @@ def commit(self, txn):
         """ See IDataManager.
         """
 
+    security.declarePrivate('invalidate')  # NOQA: D001
+
+    def invalidate(self):
+        """ See TransientObject.
+        """
+        try:
+            self._p_proxy.delete(self._p_key)
+        except KeyError:
+            pass
+
     security.declarePrivate('tpc_vote')  # NOQA: D001
 
     def tpc_vote(self, txn):

src/Products/mcdutils/tests/test_mapping.py

@@ -126,6 +126,19 @@ def test_repr(self):
             self.assertIn("'%s': '<password obscured>'" % pw_key, mapping_repr)
         self.assertIn("'normal': 'normalvalue'", mapping_repr)
 
+    def test_invalidate(self):
+        """Tests invalidate method"""
+        proxy = DummyProxy()
+        proxy._set('key', 'myvalue')
+        mapping = self._makeOne('key', proxy)
+
+        self.assertIn('key', proxy._cached)
+        mapping.invalidate()
+        self.assertNotIn('key', proxy._cached)
+
+        # Cleaning again won't throw errors
+        self.assertIsNone(mapping.invalidate())
+
 
 class DummyClient:
     def _get_server(self, key):
@@ -146,4 +159,10 @@ def _clean(self, key):
         except KeyError:
             pass
 
+    def delete(self, key):
+        try:
+            del self._cached[key]
+        except KeyError:
+            pass
+
     client = DummyClient()