better vdom checks

Author: Archmonger

src/reactpy/core/vdom.py

@@ -199,7 +199,7 @@ def separate_attributes_and_children(
 
     _attributes: VdomAttributes
     children_or_iterables: Sequence[Any]
-    if _is_attributes(values[0]):
+    if type(values[0]) is dict:
         _attributes, *children_or_iterables = values
     else:
         _attributes = {}
@@ -246,10 +246,6 @@ def _flatten_children(children: Sequence[Any]) -> list[Any]:
     return _children
 
 
-def _is_attributes(value: Any) -> bool:
-    return isinstance(value, Mapping) and "tagName" not in value
-
-
 def _is_single_child(value: Any) -> bool:
     if isinstance(value, (str, Mapping)) or not hasattr(value, "__iter__"):
         return True

src/reactpy/types.py

@@ -796,6 +796,9 @@ class VdomDict(dict):
     """A dictionary representing a virtual DOM element."""
 
     def __init__(self, **kwargs: Unpack[VdomTypeDict]) -> None:
+        if "tagName" not in kwargs:
+            msg = "VdomDict requires a 'tagName' key."
+            raise ValueError(msg)
         invalid_keys = set(kwargs) - ALLOWED_VDOM_KEYS
         if invalid_keys:
             msg = f"Invalid keys: {invalid_keys}."

tests/test_core/test_vdom.py

@@ -19,8 +19,7 @@
         (False, {}),
         (False, {"tagName": None}),
         (False, {"tagName": ""}),
-        (False, VdomTypeDict()),
-        (False, VdomDict()),
+        (False, VdomTypeDict(tagName="div")),
         (True, VdomDict(tagName="")),
         (True, VdomDict(tagName="div")),
     ],
@@ -71,7 +70,7 @@ def test_is_vdom(result, value):
         ),
         (
             reactpy.Vdom(tagName="div")({"tagName": "div"}),
-            {"tagName": "div", "children": [{"tagName": "div"}]},
+            {"tagName": "div", "attributes": {"tagName": "div"}},
         ),
         (
             reactpy.Vdom(tagName="div")((i for i in range(3))),
@@ -336,7 +335,10 @@ def test_invalid_vdom_keys():
         reactpy.Vdom()
 
     with pytest.raises(ValueError, match="Invalid keys:*"):
-        reactpy.types.VdomDict(foo="bar")
+        reactpy.types.VdomDict(tagName="test", foo="bar")
 
     with pytest.raises(KeyError, match="Invalid key:*"):
-        reactpy.types.VdomDict()["foo"] = "bar"
+        reactpy.types.VdomDict(tagName="test")["foo"] = "bar"
+
+    with pytest.raises(ValueError, match="VdomDict requires a 'tagName' key."):
+        reactpy.types.VdomDict(foo="bar")