fixes __contains__ create parent node inplicitly

chanfig/nested_dict.py

@@ -749,7 +749,10 @@ def __contains__(self, name: Any) -> bool:  # type: ignore
         try:
             while isinstance(name, str) and delimiter in name:
                 name, rest = name.split(delimiter, 1)
-                self, name = self[name], rest  # pylint: disable=W0642
+                if super().__contains__(name):
+                    self, name = self[name], rest  # pylint: disable=W0642
+                else:
+                    return False
             return super().__contains__(name)
         except (TypeError, KeyError):  # TypeError when name is not in self
             return False

tests/test_config.py

@@ -62,6 +62,12 @@ def test_nested(self):
         assert self.config.network.name == "ResNet18"
         self.config.network.nested.value = 1
 
+    def test_contains(self):
+        assert "name" in self.config
+        assert "seed" in self.config
+        assert "a.b.c" not in self.config
+        assert "a.b" not in self.config
+
     def test_variable(self):
         assert self.config.network.num_classes == 10
         self.config.network.num_classes += 1