From 000f24f1d0a306be6e28eca25990bcdaf15a5ca0 Mon Sep 17 00:00:00 2001
From: Martin Thoma <info@martin-thoma.de>
Date: Sun, 14 Aug 2022 16:58:52 +0200
Subject: [PATCH] TST: TreeObject.empty_tree()

---
 PyPDF2/generic/_data_structures.py | 20 ++++++++++----------
 tests/test_generic.py              | 16 +++++++++++++++-
 2 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/PyPDF2/generic/_data_structures.py b/PyPDF2/generic/_data_structures.py
index fae74f997..85c4e8819 100644
--- a/PyPDF2/generic/_data_structures.py
+++ b/PyPDF2/generic/_data_structures.py
@@ -359,16 +359,20 @@ def has_children(self) -> bool:
     def __iter__(self) -> Any:
         return self.children()
 
-    def children(self) -> Optional[Any]:
+    def children(self) -> Iterable[Any]:
         if not self.has_children():
             return
 
-        child = self["/First"]
+        child_ref = self[NameObject("/First")]
+        child = child_ref.get_object()
         while True:
             yield child
-            if child == self["/Last"]:
+            if child == self[NameObject("/Last")]:
                 return
-            child = child["/Next"]  # type: ignore
+            child_ref = child.get(NameObject("/Next"))  # type: ignore
+            if child_ref is None:
+                return
+            child = child_ref.get_object()
 
     def addChild(self, child: Any, pdf: Any) -> None:  # pragma: no cover
         deprecate_with_replacement("addChild", "add_child")
@@ -484,11 +488,7 @@ def emptyTree(self) -> None:  # pragma: no cover
     def empty_tree(self) -> None:
         for child in self:
             child_obj = child.get_object()
-            del child_obj[NameObject("/Parent")]
-            if NameObject("/Next") in child_obj:
-                del child_obj[NameObject("/Next")]
-            if NameObject("/Prev") in child_obj:
-                del child_obj[NameObject("/Prev")]
+            _reset_node_tree_relationship(child_obj)
 
         if NameObject("/Count") in self:
             del self[NameObject("/Count")]
@@ -650,7 +650,7 @@ def getData(self) -> Union[None, str, bytes]:  # pragma: no cover
         deprecate_with_replacement("getData", "get_data")
         return self.get_data()
 
-    def set_data(self, data: Any) -> None:
+    def set_data(self, data: Any) -> None:  # pragma: no cover
         raise PdfReadError("Creating EncodedStreamObject is not currently supported")
 
     def setData(self, data: Any) -> None:  # pragma: no cover
diff --git a/tests/test_generic.py b/tests/test_generic.py
index f94954914..13a0c6b6c 100644
--- a/tests/test_generic.py
+++ b/tests/test_generic.py
@@ -196,12 +196,16 @@ def test_destination_fit_r():
 def test_destination_fit_v():
     Destination(NameObject("title"), NullObject(), NameObject(TF.FIT_V), FloatObject(0))
 
+    # Trigger Exception
+    Destination(NameObject("title"), NullObject(), NameObject(TF.FIT_V), None)
+
 
 def test_destination_exception():
-    with pytest.raises(PdfReadError):
+    with pytest.raises(PdfReadError) as exc:
         Destination(
             NameObject("title"), NullObject(), NameObject("foo"), FloatObject(0)
         )
+    assert exc.value.args[0] == "Unknown Destination Type: 'foo'"
 
 
 def test_outline_item_write_to_stream():
@@ -450,6 +454,7 @@ def test_remove_child_found_in_tree():
     child1_ref = writer._add_object(child1)
     tree.add_child(child1_ref, writer)
     assert tree[NameObject("/Count")] == 1
+    assert len([el for el in tree.children()]) == 1
 
     # Add second child
     child2 = TreeObject()
@@ -457,10 +462,12 @@ def test_remove_child_found_in_tree():
     child2_ref = writer._add_object(child2)
     tree.add_child(child2_ref, writer)
     assert tree[NameObject("/Count")] == 2
+    assert len([el for el in tree.children()]) == 2
 
     # Remove last child
     tree.remove_child(child2)
     assert tree[NameObject("/Count")] == 1
+    assert len([el for el in tree.children()]) == 1
 
     # Add new child
     child3 = TreeObject()
@@ -468,27 +475,34 @@ def test_remove_child_found_in_tree():
     child3_ref = writer._add_object(child3)
     tree.add_child(child3_ref, writer)
     assert tree[NameObject("/Count")] == 2
+    assert len([el for el in tree.children()]) == 2
 
     # Remove first child
     child1 = tree[NameObject("/First")]
     tree.remove_child(child1)
     assert tree[NameObject("/Count")] == 1
+    assert len([el for el in tree.children()]) == 1
 
     child4 = TreeObject()
     child4[NameObject("/Foo")] = TextStringObject("4")
     child4_ref = writer._add_object(child4)
     tree.add_child(child4_ref, writer)
     assert tree[NameObject("/Count")] == 2
+    assert len([el for el in tree.children()]) == 2
 
     child5 = TreeObject()
     child5[NameObject("/Foo")] = TextStringObject("5")
     child5_ref = writer._add_object(child5)
     tree.add_child(child5_ref, writer)
     assert tree[NameObject("/Count")] == 3
+    assert len([el for el in tree.children()]) == 3
 
     # Remove middle child
     tree.remove_child(child4)
     assert tree[NameObject("/Count")] == 2
+    assert len([el for el in tree.children()]) == 2
+
+    tree.empty_tree()
 
 
 def test_remove_child_in_tree():