Preserve class in Item.clone

Author: duckontheweb

pystac/item.py

@@ -885,7 +885,8 @@ def to_dict(self, include_self_link: bool = True) -> Dict[str, Any]:
         return d
 
     def clone(self) -> "Item":
-        clone = Item(
+        cls = self.__class__
+        clone = cls(
             id=self.id,
             geometry=deepcopy(self.geometry),
             bbox=copy(self.bbox),

tests/test_item.py

@@ -743,6 +743,12 @@ def test_from_file_returns_subclass(self) -> None:
 
         self.assertIsInstance(custom_item, self.BasicCustomItem)
 
+    def test_clone(self) -> None:
+        custom_item = self.BasicCustomItem.from_file(self.SAMPLE_ITEM)
+        cloned_item = custom_item.clone()
+
+        self.assertIsInstance(cloned_item, self.BasicCustomItem)
+
 
 class AssetSubClassTest(unittest.TestCase):
     class CustomAsset(Asset):