def METHOD_NAME(self):
    files = self.files
    with open(files[0], "w", encoding="utf-8") as f:
        f.write("this line is removed\n")
    change = self.change
    change.add_validated_files(files)
    change.append_expected_add(files[0], "this is a new line")
    change.append_expected_remove(files[0], "this line is removed")
    diff_validator.make_temp_file_copies(change.get_target_files())
    changes = diff_validator.extract_changes(change.get_target_files())
    change_success = diff_validator.assert_change(changes, change.files_dict)
    change_dict = diff_validator.assert_change_dict(changes, change.files_dict)
    self.assertFalse(
        change_success,
        f"The change must not be valid:\n{diff_validator.create_diff_report(change_dict)}",
    )