Create functions with a name that starts with `test_` (this is standard `pytest` conventions).

Use the `TestClient` object the same way as you do with `httpx`.

Write simple `assert` statements with the standard Python expressions that you need to check (again, standard `pytest`).

```Python hl_lines="2  12  15-18"
{!../../../docs_src/app_testing/tutorial001.py!}
```

!!! tip

    ```Python hl_lines="10"
    {!> ../../../docs_src/query_params_str_validations/tutorial003.py!}
    ```

## Add regular expressions

You can define a <abbr title="A regular expression, regex or regexp is a sequence of characters that define a search pattern for strings.">regular expression</abbr> `pattern` that the parameter should match:

=== "Python 3.10+"

    ```Python hl_lines="11"

```Python hl_lines="9"
{!../../../docs_src/query_params_str_validations/tutorial003.py!}
```

## Ajouter des validations par expressions régulières

On peut définir une <abbr title="Une expression régulière, regex ou regexp est une suite de caractères qui définit un pattern de correspondance pour les chaînes de caractères.">expression régulière</abbr> à laquelle le paramètre doit correspondre :

```Python hl_lines="10"

def get_sequential_burgers(number: int):
    # Do some sequential stuff to create the burgers
    return burgers
```

With `async def`, Python knows that, inside that function, it has to be aware of `await` expressions, and that it can "pause" ⏸ the execution of that function and go do something else 🔀 before coming back.

When you want to call an `async def` function, you have to "await" it. So, this won't work:

```Python

    {!> ../../../docs_src/path_operation_configuration/tutorial003_py310.py!}
    ```

## 📛 ⚪️➡️ #️⃣

📛 😑 📏 &amp; 📔 💗 ⏸, 👆 💪 📣 *➡ 🛠️* 📛 🔢 <abbr title="a multi-line string as the first expression inside a function (not assigned to any variable) used for documentation"> #️⃣ </abbr> &amp; **FastAPI** 🔜 ✍ ⚫️ ⚪️➡️ 📤.

def get_sequential_burgers(number: int):
    # Opérations asynchrones pour créer les burgers
    return burgers
```

Avec `async def`, Python sait que dans cette fonction il doit prendre en compte les expressions `await`, et qu'il peut mettre en pause ⏸ l'exécution de la fonction pour aller faire autre chose 🔀 avant de revenir.

Pour appeler une fonction définie avec `async def`, vous devez utiliser `await`. Donc ceci ne marche pas :

                * `name`: (`str`) **REQUIRED** (if a `license_info` is set). The
                    license name used for the API.
                * `identifier`: (`str`) An [SPDX](https://spdx.dev/) license expression
                    for the API. The `identifier` field is mutually exclusive of the `url`
                    field. Available since OpenAPI 3.1.0, FastAPI 0.99.0.

def get_sequential_burgers(number: int):
    # Do some sequential stuff to create the burgers
    return burgers
```

Con `async def`, Python sabe que, dentro de esa función, debe tener en cuenta las expresiones `wait` y que puede "pausar" ⏸ la ejecución de esa función e ir a hacer otra cosa 🔀 antes de regresar.

Cuando desees llamar a una función `async def`, debes "esperarla". Entonces, esto no funcionará:

```Python

### The callback path expression

* *路径*可以包含 <a href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#key-expression" class="external-link" target="_blank">OpenAPI 3 表达式</a>（详见下文），可以使用带参数的变量，以及发送至您的 API 的原始请求的部分

### 回调路径表达式

回调*路径*支持包含发送给您的 API 的原始请求的部分的  <a href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#key-expression" class="external-link" target="_blank">OpenAPI 3 表达式</a>。

本例中是**字符串**：

```Python