Also check for the existence of `items` in to_primitive()

Change-Id: If4636566a642ddf2e6e13cc014abca4ad68d1977

oslo_serialization/jsonutils.py

@@ -153,6 +153,9 @@ def to_primitive(value, convert_instances=False, convert_datetime=True,
                         for k, v in six.iteritems(value))
         elif hasattr(value, 'iteritems'):
             return recursive(dict(value.iteritems()), level=level + 1)
+        # Python 3 does not have iteritems
+        elif hasattr(value, 'items'):
+            return recursive(dict(value.items()), level=level + 1)
         elif hasattr(value, '__iter__'):
             return list(map(recursive, value))
         elif convert_instances and hasattr(value, '__dict__'):

oslo_serialization/tests/test_jsonutils.py

@@ -198,6 +198,52 @@ class ToPrimitiveTestCase(test_base.BaseTestCase):
         # an exception due to excessive recursion depth.
         jsonutils.to_primitive(x)
 
+    def test_items(self):
+        # Use items() when iteritems() is not available.
+        class ItemsClass(object):
+            def __init__(self):
+                self.data = dict(a=1, b=2, c=3)
+
+            def items(self):
+                return self.data.items()
+
+        x = ItemsClass()
+        p = jsonutils.to_primitive(x)
+        self.assertEqual(p, {'a': 1, 'b': 2, 'c': 3})
+
+    def test_precedence_items_iteritems(self):
+        class ItemsIterItemsClass(object):
+            def items(self):
+                return {'items': 'items'}
+
+            def iteritems(self):
+                return {'iteritems': 'iteritems'}
+
+        x = ItemsIterItemsClass()
+        p = jsonutils.to_primitive(x)
+        # Prefer iteritems over items
+        self.assertEqual(p, {'iteritems': 'iteritems'})
+
+    def test_mapping(self):
+        # Make sure collections.Mapping is converted to a dict
+        # and not a list.
+        class MappingClass(collections.Mapping):
+            def __init__(self):
+                self.data = dict(a=1, b=2, c=3)
+
+            def __getitem__(self, val):
+                return self.data[val]
+
+            def __iter__(self):
+                return iter(self.data)
+
+            def __len__(self):
+                return len(self.data)
+
+        x = MappingClass()
+        p = jsonutils.to_primitive(x)
+        self.assertEqual(p, {'a': 1, 'b': 2, 'c': 3})
+
     def test_instance(self):
         class MysteryClass(object):
             a = 10