Added tests for latest fixes and updated changelog.

CHANGES.txt

@@ -35,6 +35,12 @@ CHANGES
   least 2 replications have been successfully been reported (w=3). It used to
   be set to w=1, which blocks until master confirms the write.
 
+- Bug: Ensure that only basic types and not objects derived from any basic
+  type are treated as such.
+
+- Bug: It can happen that comparing similar dicts can cause decode
+  errors. This in turn caused some object updates to fail in the data manager.
+
 - Bug: ObjectWriter ``get_collection_name()`` now works properly if the object
   writer has no jar. This is the case when we simply want to serialize any
   object to JSON, but one of the objects is a proper MongoDB persisted object.

src/mongopersist/tests/test_serialize.py

@@ -19,7 +19,7 @@
 
 from bson import binary, dbref, objectid
 
-from mongopersist import conflict, serialize, testing
+from mongopersist import conflict, interfaces, serialize, testing
 
 class Top(persistent.Persistent):
     _p_mongo_collection = 'Top'
@@ -55,6 +55,12 @@ class StoreType2(StoreType):
 class Simple(object):
     pass
 
+class Constant(object):
+    def __reduce__(self):
+        return 'Constant'
+Constant = Constant()
+
+
 def doctest_ObjectSerializer():
     """Test the abstract ObjectSerializer class.
 
@@ -314,6 +320,16 @@ def doctest_ObjectWriter_get_state_MONGO_NATIVE_TYPES():
       DBRef('4e7ddf12e138237403000000', 'test')
     """
 
+def doctest_ObjectWriter_get_state_constant():
+    """ObjectWriter: get_state(): Constants
+
+      >>> writer = serialize.ObjectWriter(None)
+      >>> writer.get_state(Constant)
+      {'_py_constant': 'mongopersist.tests.test_serialize.Constant'}
+      >>> writer.get_state(interfaces.IObjectWriter)
+      {'_py_constant': 'mongopersist.interfaces.IObjectWriter'}
+    """
+
 def doctest_ObjectWriter_get_state_types():
     """ObjectWriter: get_state(): types (type, class)
 
@@ -874,6 +890,19 @@ def doctest_ObjectReader_get_object_mapping():
       {1: '1', 2: '2', 3: '3'}
     """
 
+def doctest_ObjectReader_get_object_constant():
+    """ObjectReader: get_object(): constant
+
+      >>> reader = serialize.ObjectReader(dm)
+      >>> reader.get_object(
+      ...     {'_py_constant': 'mongopersist.tests.test_serialize.Constant'},
+      ...     None)
+      <mongopersist.tests.test_serialize.Constant object at ...>
+      >>> reader.get_object(
+      ...     {'_py_constant': 'mongopersist.interfaces.IObjectWriter'}, None)
+      <InterfaceClass mongopersist.interfaces.IObjectWriter>
+    """
+
 def doctest_ObjectReader_get_ghost():
     """ObjectReader: get_ghost()