Fix deepcopy of TaggedList

CHANGES.rst

@@ -4,6 +4,9 @@
 - Fix bug preventing diff of files containing ndarray-1.0.0
   objects in simplified form. [#786]
 
+- Fix bug causing duplicate elements to appear when calling
+  ``copy.deepcopy`` on a ``TaggedList``. [#788]
+
 2.6.0 (2020-04-22)
 ------------------
 

asdf/tagged.py

@@ -32,6 +32,7 @@
 """
 
 from collections import UserDict, UserList, UserString
+from copy import deepcopy, copy
 
 
 __all__ = ['tag_object', 'get_tag']
@@ -63,6 +64,14 @@ def __eq__(self, other):
                 self.data == other.data and
                 self._tag == other._tag)
 
+    def __deepcopy__(self, memo):
+        data_copy = deepcopy(self.data, memo)
+        return TaggedDict(data_copy, self._tag)
+
+    def __copy__(self):
+        data_copy = copy(self.data)
+        return TaggedDict(data_copy, self._tag)
+
 
 class TaggedList(Tagged, UserList, list):
     """
@@ -81,6 +90,14 @@ def __eq__(self, other):
                 self.data == other.data and
                 self._tag == other._tag)
 
+    def __deepcopy__(self, memo):
+        data_copy = deepcopy(self.data, memo)
+        return TaggedList(data_copy, self._tag)
+
+    def __copy__(self):
+        data_copy = copy(self.data)
+        return TaggedList(data_copy, self._tag)
+
 
 class TaggedString(Tagged, UserString, str):
     """

asdf/tests/test_tagged.py

@@ -0,0 +1,82 @@
+from copy import deepcopy, copy
+
+from asdf.tagged import TaggedList, TaggedDict, TaggedString
+
+
+def test_tagged_list_deepcopy():
+    original = TaggedList([0, 1, 2, ["foo"]], "tag:nowhere.org:custom/foo-1.0.0")
+    result = deepcopy(original)
+    assert result == original
+    assert result.data == original.data
+    assert result._tag == original._tag
+    original.append(4)
+    assert len(result) == 4
+    original[3].append("bar")
+    assert len(result[3]) == 1
+
+
+def test_tagged_list_copy():
+    original = TaggedList([0, 1, 2, ["foo"]], "tag:nowhere.org:custom/foo-1.0.0")
+    result = copy(original)
+    assert result == original
+    assert result.data == original.data
+    assert result._tag == original._tag
+    original.append(4)
+    assert len(result) == 4
+    original[3].append("bar")
+    assert len(result[3]) == 2
+
+
+def test_tagged_list_isinstance():
+    value = TaggedList([0, 1, 2, ["foo"]], "tag:nowhere.org:custom/foo-1.0.0")
+    assert isinstance(value, list)
+
+
+def test_tagged_dict_deepcopy():
+    original = TaggedDict({"a": 0, "b": 1, "c": 2, "nested": {"d": 3}}, "tag:nowhere.org:custom/foo-1.0.0")
+    result = deepcopy(original)
+    assert result == original
+    assert result.data == original.data
+    assert result._tag == original._tag
+    original["e"] = 4
+    assert len(result) == 4
+    original["nested"]["f"] = 5
+    assert len(result["nested"]) == 1
+
+
+def test_tagged_dict_copy():
+    original = TaggedDict({"a": 0, "b": 1, "c": 2, "nested": {"d": 3}}, "tag:nowhere.org:custom/foo-1.0.0")
+    result = copy(original)
+    assert result == original
+    assert result.data == original.data
+    assert result._tag == original._tag
+    original["e"] = 4
+    assert len(result) == 4
+    original["nested"]["f"] = 5
+    assert len(result["nested"]) == 2
+
+
+def test_tagged_dict_isinstance():
+    value = TaggedDict({"a": 0, "b": 1, "c": 2, "nested": {"d": 3}}, "tag:nowhere.org:custom/foo-1.0.0")
+    assert isinstance(value, dict)
+
+
+def test_tagged_string_deepcopy():
+    original = TaggedString("You're it!")
+    original._tag = "tag:nowhere.org:custom/foo-1.0.0"
+    result = deepcopy(original)
+    assert result == original
+    assert result._tag == original._tag
+
+
+def test_tagged_string_copy():
+    original = TaggedString("You're it!")
+    original._tag = "tag:nowhere.org:custom/foo-1.0.0"
+    result = copy(original)
+    assert result == original
+    assert result._tag == original._tag
+
+
+def test_tagged_string_isinstance():
+    value = TaggedString("You're it!")
+    assert isinstance(value, str)