feat: make meaningful errors for subclass

ntc/node.py

@@ -322,7 +322,10 @@ def _set_new(self, key: str, value: Any) -> None:
                 if leaf_spec.required and not value_to_set.required:
                     raise SchemaError(f"Leaf {value_to_set} must have required == True")
                 if leaf_spec.subclass != value_to_set.subclass:
-                    raise SchemaError(f"Leaf {value_to_set} must have subclass == True")
+                    if leaf_spec.subclass:
+                        raise SchemaError(f"Leaf {value_to_set} must be a type (subclass == True)")
+                    else:
+                        raise SchemaError(f"Leaf {value_to_set} cannot be a type (subclass == False)")
                 if not issubclass(value_to_set.type, leaf_spec.type):
                     raise SchemaError(f"Required type for leaf {value_to_set} must be subclass of {leaf_spec.type}")
                 if not leaf_spec.required and value_to_set.value is None:

tests/data/bad/bad_inherit_subclass_class.py

@@ -0,0 +1,6 @@
+from ..base_cfg import cfg
+from ..base_class import BaseClass
+
+cfg = cfg.clone()
+
+cfg.CLASSES.ANOTHER = BaseClass

tests/data/bad/bad_inherit_subclass_class_changes.py

@@ -0,0 +1,4 @@
+from ntc import CN
+from tests.data.bad.bad_inherit_subclass import cfg
+
+cfg = CN(cfg)

tests/test_bad.py

@@ -72,6 +72,11 @@ def test_bad_inherit_subclass_instance():
         CN.load(DATA_DIR / "bad_inherit_subclass_instance_changes.py")
 
 
+def test_bad_inherit_subclass_class():
+    with pytest.raises(SchemaError):
+        CN.load(DATA_DIR / "bad_inherit_subclass_class_changes.py")
+
+
 def test_schema_freeze():
     with pytest.raises(SchemaError):
         CN.load(DATA_DIR / "bad_schema.py")