Have node_setattr delete keys when the value to set is None.

Note that this looks at the value directly; when using {'key': None} as
value, it is not None and thus will be set. This thus is NOT a way to
be 100% sure there are no None values.

attract/shots/__init__.py

@@ -135,14 +135,18 @@ class ShotManager(object):
 def node_setattr(node, key, value):
     """Sets a node property by dotted key.
 
-    Modifies the node in-place.
+    Modifies the node in-place. Deletes None values.
     """
 
     set_on = node
     while key and '.' in key:
         head, key = key.split('.', 1)
-        set_on = node[head]
-    set_on[key] = value
+        set_on = set_on[head]
+
+    if value is None:
+        set_on.pop(key, None)
+    else:
+        set_on[key] = value
 
 
 @register_patch_handler(node_type_shot['name'])

tests/test_shots.py

@@ -157,7 +157,7 @@ class NodeSetattrTest(unittest.TestCase):
         node = {}
         node_setattr(node, 'a', None)
         node_setattr(node, None, 'b')
-        self.assertEqual({'a': None, None: 'b'}, node)
+        self.assertEqual({None: 'b'}, node)
 
     def test_none_dotted(self):
         from attract.shots import node_setattr
@@ -167,15 +167,16 @@ class NodeSetattrTest(unittest.TestCase):
 
         node = {'b': {}}
         node_setattr(node, 'b.simple', None)
-        self.assertEqual({'b': {'simple': None}}, node)
+        self.assertEqual({'b': {}}, node)
 
         node_setattr(node, 'b.complex', {'yes': None})
-        self.assertEqual({'b': {'simple': None,
-                                'complex': {'yes': None}}}, node)
+        self.assertEqual({'b': {'complex': {'yes': None}}}, node)
+
+        node_setattr(node, 'b.complex.yes', None)
+        self.assertEqual({'b': {'complex': {}}}, node)
 
         node_setattr(node, 'b.complex', {None: 5})
-        self.assertEqual({'b': {'simple': None,
-                                'complex': {None: 5}}}, node)
+        self.assertEqual({'b': {'complex': {None: 5}}}, node)
 
 
 class PatchShotTest(AbstractShotTest):