# Testing Dependencies with Overrides

## Overriding dependencies during testing

There are some scenarios where you might want to override a dependency during testing.

You don't want the original dependency to run (nor any of the sub-dependencies it might have).

    ```Python hl_lines="26-27  30"
    {!> ../../../docs_src/dependency_testing/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="28-29  32"
    {!> ../../../docs_src/dependency_testing/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="29-30  33"
    {!> ../../../docs_src/dependency_testing/tutorial001_an.py!}
    ```

=== "Python 3.10+ nicht annotiert"

# 🔬 *️⃣

👆 💪 ⚙️ 🎏 `TestClient` 💯*️⃣.

👉, 👆 ⚙️ `TestClient` `with` 📄, 🔗*️⃣:

```Python hl_lines="27-31"
{!../../../docs_src/app_testing/tutorial002.py!}
```

!!! note

# 测试数据库

您还可以使用[测试依赖项](testing-dependencies.md){.internal-link target=_blank}中的覆盖依赖项方法变更测试的数据库。

实现设置其它测试数据库、在测试后回滚数据、或预填测试数据等操作。

本章的主要思路与上一章完全相同。

## 为 SQL 应用添加测试

为了使用测试数据库，我们要升级 [SQL 关系型数据库](../tutorial/sql-databases.md){.internal-link target=_blank} 一章中的示例。

应用的所有代码都一样，直接查看那一章的示例代码即可。

本章只是新添加了测试文件。

正常的依赖项 `get_db()` 返回数据库会话。

测试时使用覆盖依赖项返回自定义数据库会话代替正常的依赖项。

本例中，要创建仅用于测试的临时数据库。

## 文件架构

import importlib
import os
from pathlib import Path

import pytest

from ...utils import needs_py39, needs_pydanticv1


@needs_py39
# TODO: pv2 add version with Pydantic v2
@needs_pydanticv1
def test_testing_dbs_py39(tmp_path_factory: pytest.TempPathFactory):
    tmp_path = tmp_path_factory.mktemp("data")
    cwd = os.getcwd()
    os.chdir(tmp_path)
    test_db = Path("./test.db")
    if test_db.is_file():  # pragma: nocover

## Atualizando as versões do FastAPI

Você deve adicionar testes para a sua aplicação.

Com **FastAPI** isso é muito fácil (graças a Starlette), verifique a documentação: [Testing](../tutorial/testing.md){.internal-link target=\_blank}

Após a criação dos testes, você pode atualizar a sua versão do **FastAPI** para uma mais recente, execute os testes para se certificar de que todo o seu código está funcionando corretamente.

    ```Python hl_lines="16  18-20"
    {!> ../../../docs_src/settings/app02/main.py!}
    ```

### Settings and testing

Then it would be very easy to provide a different settings object during testing by creating a dependency override for `get_settings`:

```Python hl_lines="9-10  13  21"
{!../../../docs_src/settings/app02/test_main.py!}
```

from ...utils import needs_py310


@needs_py310
def test_app():
    from docs_src.app_testing.app_b_an_py310 import test_main

    test_main.test_create_existing_item()
    test_main.test_create_item()
    test_main.test_create_item_bad_token()
    test_main.test_read_nonexistent_item()
    test_main.test_read_item()

from docs_src.dependency_testing.tutorial001_an import (
    app,
    client,
    test_override_in_items,
    test_override_in_items_with_params,
    test_override_in_items_with_q,
)


def test_override_in_items_run():
    test_override_in_items()


def test_override_in_items_with_q_run():
    test_override_in_items_with_q()


def test_override_in_items_with_params_run():
    test_override_in_items_with_params()

=== "Python 3.10+"

    ```Python
    {!> ../../../docs_src/app_testing/app_b_an_py310/main.py!}
    ```

=== "Python 3.9+"

    ```Python
    {!> ../../../docs_src/app_testing/app_b_an_py39/main.py!}
    ```

=== "Python 3.8+"

    ```Python
    {!> ../../../docs_src/app_testing/app_b_an/main.py!}
    ```

=== "Python 3.10+ без Annotated"

    !!! tip "Подсказка"