diff --git a/.gitignore b/.gitignore
index c68be1b..8e237ab 100644
--- a/.gitignore
+++ b/.gitignore
@@ -25,4 +25,5 @@ __pycache__
 build
 src/rune.runtime.egg-info
 rune.runtime-*.whl
-src/rune/runtime/version.py
\ No newline at end of file
+src/rune/runtime/version.py
+/.coverage
diff --git a/pyproject.toml b/pyproject.toml
index e018721..438a733 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -11,6 +11,7 @@ dependencies = [
 ]
 optional-dependencies.dev = [
     "pytest",
+    "pytest-cov",
     "pytest-mock"
 ]
 description = "rune-runtime: the Rune DSL runtime for Python"
diff --git a/src/rune/runtime/metadata.py b/src/rune/runtime/metadata.py
index 4151548..7816e54 100644
--- a/src/rune/runtime/metadata.py
+++ b/src/rune/runtime/metadata.py
@@ -1,14 +1,15 @@
 '''Classes representing annotated basic Rune types'''
-from enum import Enum
+import uuid
+import datetime
 import importlib
+from enum import Enum
 from functools import partial, lru_cache
-import uuid
 from decimal import Decimal
 from typing import Any, Never, get_args
-import datetime
 from typing_extensions import Self, Tuple
 from pydantic import (PlainSerializer, PlainValidator, WrapValidator,
                       WrapSerializer)
+from pydantic_core import PydanticCustomError
 # from rune.runtime.object_registry import get_object
 
 META_CONTAINER = '__rune_metadata'
@@ -365,6 +366,11 @@ def deserialize(cls, obj, allowed_meta: set[str]):
         if isinstance(obj, Reference):
             return obj
 
+        if not isinstance(obj, dict):
+            raise PydanticCustomError('Input Validation Error',
+                                      'Expected either {my_type} or dict but '
+                                      'got {type}.',
+                                      {'type': type(obj), 'my_type': cls})
         metadata = {k: obj[k] for k in obj.keys() if k.startswith('@')}
 
         # References deserialization treatment
diff --git a/test/cdm/test_validation.py b/test/cdm/test_validation.py
new file mode 100644
index 0000000..6f928dd
--- /dev/null
+++ b/test/cdm/test_validation.py
@@ -0,0 +1,23 @@
+'''Full attribute validation - pydantic and constraints'''
+import pytest
+from pydantic import ValidationError
+try:
+    # pylint: disable=unused-import
+    # type: ignore
+    from cdm.base.math.NonNegativeQuantity import NonNegativeQuantity
+    from cdm.base.math.UnitType import UnitType
+    NO_SER_TEST_MOD = False
+except ImportError:
+    NO_SER_TEST_MOD = True
+
+
+@pytest.mark.skipif(NO_SER_TEST_MOD, reason='CDM package not found')
+def test_bad_attrib_validation():
+    '''Invalid attribute assigned'''
+    unit = UnitType(currency='EUR')
+    mq = NonNegativeQuantity(value=10, unit=unit)
+    mq.frequency = 'Blah'
+    with pytest.raises(ValidationError):
+        mq.validate_model()
+
+# EOF
diff --git a/test/serializer-round-trip/test_enumtype.py b/test/serializer-round-trip/test_enumtype.py
index ab23c75..db13daa 100644
--- a/test/serializer-round-trip/test_enumtype.py
+++ b/test/serializer-round-trip/test_enumtype.py
@@ -15,10 +15,19 @@
 @pytest.mark.skipif(NO_SER_TEST_MOD, reason='Generated test package not found')
 def test_enum_types_single():
     '''no doc'''
+    # import serialization.test.passing.enumtypes.Root
+    # import serialization.test.passing.enumtypes.EnumSingle
+    # import serialization.test.passing.enumtypes.EnumType
+
+    # root = serialization.test.passing.enumtypes.Root.Root(
+    #     enumSingle=serialization.test.passing.enumtypes.EnumSingle.EnumSingle(
+    #         enumType=serialization.test.passing.enumtypes.EnumType.EnumType.A
+    #     ))
+    # resp_json = root.rune_serialize()
     json_str = '''
         {
             "@model": "serialization",
-            "@type": "serialization.test.enumtypes.Root",
+            "@type": "serialization.test.passing.enumtypes.Root",
             "@version": "0.0.0",
             "enumSingle": {
                 "enumType": "A"
@@ -36,7 +45,7 @@ def test_enum_types_list():
     json_str = '''
         {
             "@model": "serialization",
-            "@type": "serialization.test.enumtypes.Root",
+            "@type": "serialization.test.passing.enumtypes.Root",
             "@version": "0.0.0",
             "enumList": {
                 "enumType": ["A", "B", "C", "B"]
diff --git a/test/serializer-round-trip/test_extension.py b/test/serializer-round-trip/test_extension.py
index aa86846..f70cf5c 100644
--- a/test/serializer-round-trip/test_extension.py
+++ b/test/serializer-round-trip/test_extension.py
@@ -18,7 +18,7 @@ def test_base_type():
     '''no doc'''
     json_str = '''{
         "@model": "serialization",
-        "@type": "serialization.test.extension.Root",
+        "@type": "serialization.test.passing.extension.Root",
         "@version": "0.0.0",
         "typeA": {
             "fieldA": "foo"
@@ -34,12 +34,12 @@ def test_extended_type_concrete():
     '''no doc'''
     json_str = '''{
         "@model": "serialization",
-        "@type": "serialization.test.extension.Root",
+        "@type": "serialization.test.passing.extension.Root",
         "@version": "0.0.0",
         "typeB": {
             "fieldA": "foo",
             "fieldB": "foo",
-            "@type": "serialization.test.extension.B"
+            "@type": "serialization.test.passing.extension.B"
         }
     }'''
     model = BaseDataClass.rune_deserialize(json_str)
@@ -55,15 +55,15 @@ def test_extended_type_polymorphic():
     '''no doc'''
     json_str = '''{
         "@model": "serialization",
-        "@type": "serialization.test.extension.Root",
+        "@type": "serialization.test.passing.extension.Root",
         "@version": "0.0.0",
         "typeA": {
             "fieldA": "bar",
             "fieldB": "foo",
-            "@type": "serialization.test.extension.B"
+            "@type": "serialization.test.passing.extension.B"
         }
     }'''
-    # import serialization.test.extension.Root
+    # import serialization.test.passing.extension.Root
     model = BaseDataClass.rune_deserialize(json_str)
     resp_json = model.rune_serialize()
     assert json.loads(resp_json) == json.loads(json_str)
@@ -72,14 +72,14 @@ def test_extended_type_polymorphic():
 @pytest.mark.skipif(NO_SER_TEST_MOD, reason='Generated test package not found')
 def test_at_type():
     '''no doc'''
-    from serialization.test.extension.B import B
+    from serialization.test.passing.extension.B import B
     json_str = '''
         {
-            "@type": "serialization.test.extension.Root",
+            "@type": "serialization.test.passing.extension.Root",
             "typeA" : {
                 "fieldA" : "bar",
                 "fieldB" : "foo",
-                "@type" : "serialization.test.extension.B"
+                "@type" : "serialization.test.passing.extension.B"
             }
         }
     '''
@@ -90,7 +90,7 @@ def test_at_type():
 @pytest.mark.skipif(NO_SER_TEST_MOD, reason='Generated test package not found')
 def test_temp():
     '''no doc'''
-    from serialization.test.metakey.Root import Root
+    from serialization.test.passing.metakey.Root import Root
     json_str = '''
     {
         "nodeRef" : {
@@ -112,7 +112,7 @@ def test_temp():
 @pytest.mark.skipif(NO_SER_TEST_MOD, reason='Generated test package not found')
 def test_enums():
     '''no doc'''
-    from serialization.test.enumtypes.Root import Root
+    from serialization.test.passing.enumtypes.Root import Root
     json_str = '{"enumSingle":{"enumType":"A"}}'
     json_dict = json.loads(json_str)
     model1 = Root.model_validate(json_dict)
diff --git a/test/serializer-round-trip/test_metakey.py b/test/serializer-round-trip/test_metakey.py
index 56782c9..744f321 100644
--- a/test/serializer-round-trip/test_metakey.py
+++ b/test/serializer-round-trip/test_metakey.py
@@ -172,7 +172,7 @@ def test_generated_attribute_ref():
     '''attribute-ref.json'''
     json_str = '''{
         "@model": "serialization",
-        "@type": "serialization.test.metakey.Root",
+        "@type": "serialization.test.passing.metakey.Root",
         "@version": "0.0.0",
         "attributeRef": {
             "dateField": {
@@ -198,7 +198,7 @@ def test_generated_node_ref():
     '''attribute-ref.json'''
     json_str = '''{
         "@model": "serialization",
-        "@type": "serialization.test.metakey.Root",
+        "@type": "serialization.test.passing.metakey.Root",
         "@version": "0.0.0",
         "nodeRef": {
             "typeA": {
@@ -224,7 +224,7 @@ def test_generated_dangling_node_ref():
     '''attribute-ref.json'''
     json_str = '''{
         "@model": "serialization",
-        "@type": "serialization.test.metakey.Root",
+        "@type": "serialization.test.passing.metakey.Root",
         "@version": "0.0.0",
         "nodeRef": {
             "aReference": {
@@ -243,7 +243,7 @@ def test_generated_dangling_attribute_ref():
     '''attribute-ref.json'''
     json_str = '''{
         "@model": "serialization",
-        "@type": "serialization.test.metakey.Root",
+        "@type": "serialization.test.passing.metakey.Root",
         "@version": "0.0.0",
         "attributeRef": {
             "dateReference": {
diff --git a/test/serializer-round-trip/test_metalocation.py b/test/serializer-round-trip/test_metalocation.py
index 0bf4d56..b0e0bc5 100644
--- a/test/serializer-round-trip/test_metalocation.py
+++ b/test/serializer-round-trip/test_metalocation.py
@@ -18,7 +18,7 @@ def test_address():
     '''no doc'''
     json_str = '''    {
         "@model": "serialization",
-        "@type": "serialization.test.metalocation.Root",
+        "@type": "serialization.test.passing.metalocation.Root",
         "@version": "0.0.0",
         "typeA": {
             "b": {
diff --git a/test/serializer-round-trip/test_metascheme.py b/test/serializer-round-trip/test_metascheme.py
index cc529d0..bf4f936 100644
--- a/test/serializer-round-trip/test_metascheme.py
+++ b/test/serializer-round-trip/test_metascheme.py
@@ -18,7 +18,7 @@ def test_enum_single():
     json_str = '''
         {
             "@model": "serialization",
-            "@type": "serialization.test.metascheme.Root",
+            "@type": "serialization.test.passing.metascheme.Root",
             "@version": "0.0.0",
             "enumType": {
                 "@data": "A",
@@ -37,7 +37,7 @@ def test_enum_list():
     json_str = '''
     {
         "@model": "serialization",
-        "@type": "serialization.test.metascheme.Root",
+        "@type": "serialization.test.passing.metascheme.Root",
         "@version": "0.0.0",
         "enumTypeList": [{
             "@data": "A",