def assert_file_not_contains(self, filename: str, pattern: str):
        with open(filename, 'rb', 0) as file, mmap.mmap(file.fileno(), 0, access=mmap.ACCESS_READ) as content:
            if content.find(bytes(pattern, 'utf-8')) != -1:
                self.fail(f"File {filename} not contains pattern - {pattern}")