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   "source": [
    "# 22-31 · Проверяем ввод\n",
    "\n",
    "Практика к разделу [«Проверка входных данных и обработка ошибок»](../../site/chapters/glava-22/22-31-validaciya-oshibki.html)."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "7ca948e4",
   "metadata": {},
   "source": [
    "## Цель\n",
    "\n",
    "Проверить ту же функцию clean_title(), которая используется в настоящем проекте (projects/flask/todo-app/app.py), на нескольких граничных случаях."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "65532c37",
   "metadata": {},
   "source": [
    "## Рабочий пример"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "deb24823",
   "metadata": {},
   "outputs": [],
   "source": [
    "MAX_TITLE_LENGTH = 200\n",
    "\n",
    "\n",
    "def clean_title(raw_title):\n",
    "    title = raw_title.strip()\n",
    "    if not title or len(title) > MAX_TITLE_LENGTH:\n",
    "        return None\n",
    "    return title\n",
    "\n",
    "\n",
    "print(clean_title(\"Купить хлеб\"))\n",
    "print(clean_title(\"   \"))\n",
    "print(clean_title(\"а\" * 201))"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "83654613",
   "metadata": {},
   "source": [
    "## Проверка результата"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "99d62142",
   "metadata": {},
   "outputs": [],
   "source": [
    "assert clean_title(\"Купить хлеб\") == \"Купить хлеб\"\n",
    "assert clean_title(\"  Пробелы по краям  \") == \"Пробелы по краям\"\n",
    "assert clean_title(\"\") is None\n",
    "assert clean_title(\"   \") is None\n",
    "assert clean_title(\"а\" * 200) == \"а\" * 200\n",
    "assert clean_title(\"а\" * 201) is None\n",
    "print(\"Верно: пустой, состоящий из пробелов и слишком длинный ввод отклоняются.\")"
   ]
  }
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