Refs #32948 -- Added more tests for django.utils.tree.Node.

The tests for creating new instances or copying instances of Node and
its subclasses didn't fully capture the behaviour of the implementation,
particularly around whether the `children` list or is contents were the
same as the source.

tests/utils_tests/test_tree.py

@@ -69,11 +69,45 @@ class NodeTests(unittest.TestCase):
         self.node1.negate()
         self.assertFalse(self.node1.negated)
 
+    def test_new_instance(self):
+        SubNode = type("SubNode", (Node,), {})
+
+        a = SubNode([SubNode(["a", "b"], OR), "c"], AND)
+        b = SubNode._new_instance(a.children, a.connector, a.negated)
+        self.assertEqual(a, b)
+        # Children lists are the same object, but equal.
+        self.assertIsNot(a.children, b.children)
+        self.assertEqual(a.children, b.children)
+        # Child Node objects are the same objects.
+        for a_child, b_child in zip(a.children, b.children):
+            if isinstance(a_child, Node):
+                self.assertIs(a_child, b_child)
+            self.assertEqual(a_child, b_child)
+
+    def test_copy(self):
+        a = Node([Node(["a", "b"], OR), "c"], AND)
+        b = copy.copy(a)
+        self.assertEqual(a, b)
+        # Children lists are the same object.
+        self.assertIs(a.children, b.children)
+        # Child Node objects are the same objects.
+        for a_child, b_child in zip(a.children, b.children):
+            if isinstance(a_child, Node):
+                self.assertIs(a_child, b_child)
+            self.assertEqual(a_child, b_child)
+
     def test_deepcopy(self):
-        node4 = copy.copy(self.node1)
-        node5 = copy.deepcopy(self.node1)
-        self.assertIs(self.node1.children, node4.children)
-        self.assertIsNot(self.node1.children, node5.children)
+        a = Node([Node(["a", "b"], OR), "c"], AND)
+        b = copy.deepcopy(a)
+        self.assertEqual(a, b)
+        # Children lists are not be the same object, but equal.
+        self.assertIsNot(a.children, b.children)
+        self.assertEqual(a.children, b.children)
+        # Child Node objects are not be the same objects.
+        for a_child, b_child in zip(a.children, b.children):
+            if isinstance(a_child, Node):
+                self.assertIsNot(a_child, b_child)
+            self.assertEqual(a_child, b_child)
 
     def test_eq_children(self):
         node = Node(self.node1_children)