def test_deleting_only_node_should_leave_the_tree_empty():
object_under_test = BinarySearchTree()
object_under_test.insert(22)
object_under_test.delete(22)
assert not object_under_test.traverse_preorder()
def test_deleting_node_with_only_left_child_hould_replace_the_node_with_the_only_child():
object_under_test = BinarySearchTree()
object_under_test.insert(55)
object_under_test.insert(44)
object_under_test.insert(33)
object_under_test.delete(44)
assert [55, 33] == object_under_test.traverse_preorder()
def test_deleting_node_with_two_children_should_replace_the_node_with_successor():
object_under_test = BinarySearchTree()
object_under_test.insert(44)
object_under_test.insert(33)
object_under_test.insert(55)
object_under_test.delete(44)
assert [55, 33] == object_under_test.traverse_preorder()
def test_deleting_left_leaf_should_cause_tree_to_lose_the_leaf():
object_under_test = BinarySearchTree()
object_under_test.insert(44)
object_under_test.insert(33)
object_under_test.insert(55)
object_under_test.delete(33)
assert [44, 55] == object_under_test.traverse_preorder()
def test_deleting_nonexistent_value_should_raise():
object_under_test = BinarySearchTree()
object_under_test.insert(44)
nonexistent_value = 22
with pytest.raises(ValueNotFoundInTreeError) as err:
object_under_test.delete(nonexistent_value)
assert f"{nonexistent_value}" in str(err)