Example content types needs to inherit from IResource

src/plone.server/plone/server/catalog/catalog.py

@@ -85,7 +85,7 @@ def get_data(self, ob, iface, field_name):
             real_field = field.bind(ob)
             try:
                 value = real_field.get(ob)
-                json_compatible(value)
+                return json_compatible(value)
             except AttributeError:
                 pass
         except KeyError:
@@ -96,6 +96,7 @@ def get_data(self, ob, iface, field_name):
     def __call__(self):
         # For each type
         values = {}
+
         for schema in iter_schemata_for_type(self.content.portal_type):
             behavior = schema(self.content)
             for index_name, index_data in merged_tagged_value_dict(schema, index.key).items():

src/plone.server/plone/server/testing.py

@@ -6,7 +6,7 @@
 from plone.server.factory import make_app
 from zope.component import getUtility
 from zope.configuration.xmlconfig import include
-from zope.interface import Interface
+from plone.server.interfaces import IResource
 from zope.security.interfaces import IInteraction
 from plone.server.api.layer import IDefaultLayer
 from plone.server.interfaces import IRequest
@@ -83,7 +83,7 @@
 })
 
 
-class IExample(Interface):
+class IExample(IResource):
 
     metadata('categories')