def test_delete_node_is_none(self):
bst = BinarySearchTree(data=5)
bst.insert(3)
bst.insert(7)
bst.insert(1)
bst.insert(2)
bst.insert(9)
bst.insert(6)
self.assertEqual(bst.delete(3, None), None)
def test_delete_successful_left_subtree(self):
bst = BinarySearchTree(data=5)
bst.insert(3)
bst.insert(7)
bst.insert(1)
bst.insert(4)
bst.insert(2)
bst.insert(9)
bst.insert(6)
self.assertIsNotNone(bst.delete(3, bst.root))
self.assertIsNone(bst.root.left.right)
self.assertEqual(bst.root.left.data, 4)
self.assertIsNotNone(bst.delete(4, bst.root))
self.assertEqual(bst.root.left.data, 1)
self.assertIsNotNone(bst.delete(1, bst.root))
self.assertIsNotNone(bst.delete(2, bst.root))
def test_delete_successful_right_subtree(self):
bst = BinarySearchTree(data=5)
bst.insert(3)
bst.insert(7)
bst.insert(1)
bst.insert(2)
bst.insert(9)
bst.insert(6)
self.assertIsNotNone(bst.delete(5, bst.root))
self.assertEqual(bst.root.data, 6)
self.assertEqual(bst.root.right.data, 7)
self.assertEqual(bst.root.right.right.data, 9)
self.assertIsNone(bst.root.right.left)
self.assertIsNone(bst.root.right.right.left)
self.assertIsNotNone(bst.delete(9, bst.root))
self.assertEqual(bst.root.data, 6)
self.assertEqual(bst.root.right.data, 7)
self.assertIsNone(bst.root.right.left)
self.assertIsNone(bst.root.right.right)