Check object's field

A nova object should have all fields as instance of fields.Field.
This patch adds a check on the metaclass to make sure of it.

This check happens only when class import so should have no
runtime performance impact.

Change-Id: I2cdf7eb097fb6907cbd048fa73138b352ab547d7

nova/exception.py

@@ -1381,6 +1381,10 @@ class ObjectActionError(NovaException):
     msg_fmt = _('Object action %(action)s failed because: %(reason)s')
 
 
+class ObjectFieldInvalid(NovaException):
+    msg_fmt = _('Field %(field)s of %(objname)s is not an instance of Field')
+
+
 class CoreAPIMissing(NovaException):
     msg_fmt = _("Core API extensions are missing: %(missing_apis)s")
 

nova/objects/base.py

@@ -56,6 +56,9 @@ def make_class_properties(cls):
             if name not in cls.fields:
                 cls.fields[name] = field
     for name, field in cls.fields.iteritems():
+        if not isinstance(field, fields.Field):
+            raise exception.ObjectFieldInvalid(
+                field=name, objname=cls.obj_name())
 
         def getter(self, name=name):
             attrname = get_attrname(name)

nova/tests/objects/test_objects.py

@@ -138,6 +138,19 @@ class TestMetaclass(test.TestCase):
         self.assertEqual(expected, Test1._obj_classes)
         self.assertEqual(expected, Test2._obj_classes)
 
+    def test_field_checking(self):
+        def create_class(field):
+            class TestField(base.NovaObject):
+                VERSION = '1.5'
+                fields = {'foo': field()}
+            return TestField
+
+        cls = create_class(fields.IPV4AndV6AddressField)
+        self.assertRaises(exception.ObjectFieldInvalid,
+                          create_class, fields.IPV4AndV6Address)
+        self.assertRaises(exception.ObjectFieldInvalid,
+                          create_class, int)
+
 
 class TestObjToPrimitive(test.TestCase):