Return instances of the right type when calling clone or casting it…

…ems in a `benedict` subclass. #115

benedict/dicts/__init__.py

@@ -53,7 +53,8 @@ def __init__(self, *args, **kwargs):
         super(benedict, self).__init__(*args, **kwargs)
 
     def __deepcopy__(self, memo):
-        obj = benedict(keypath_separator=self._keypath_separator)
+        obj_type = type(self)
+        obj = obj_type(keypath_separator=self._keypath_separator)
         for key, value in self.items():
             obj[key] = _clone(value, memo=memo)
         return obj
@@ -66,8 +67,9 @@ def _cast(self, value):
         Cast a dict instance to a benedict instance
         keeping the pointer to the original dict.
         """
-        if isinstance(value, dict) and not isinstance(value, benedict):
-            return benedict(
+        obj_type = type(self)
+        if isinstance(value, dict) and not isinstance(value, obj_type):
+            return obj_type(
                 value, keypath_separator=self._keypath_separator, check_keys=False
             )
         return value

tests/dicts/test_benedict_subclass.py

@@ -0,0 +1,39 @@
+# -*- coding: utf-8 -*-
+
+from benedict import benedict
+
+import unittest
+
+
+class subbenedict(benedict):
+    pass
+
+
+class benedict_subclass_test_case(unittest.TestCase):
+    """
+    This class describes a benedict subclass test case.
+    """
+
+    def test_cast(self):
+        d = subbenedict(
+            {
+                "a": {
+                    "b": {
+                        "c": {
+                            "d": True,
+                        },
+                    }
+                }
+            }
+        )
+        c = d["a.b.c"]
+        self.assertTrue(issubclass(type(c), benedict))
+        self.assertTrue(isinstance(c, subbenedict))
+        self.assertEqual(c, {"d": True})
+
+    def test_clone(self):
+        d = subbenedict({"a": True})
+        c = d.clone()
+        self.assertTrue(issubclass(type(c), benedict))
+        self.assertTrue(isinstance(c, subbenedict))
+        self.assertEqual(c, {"a": True})