The only changes here are in the new testing file.

Your normal dependency `get_db()` would return a database session.

In the test, you could use a dependency override to return your *custom* database session instead of the one that would be used normally.

In this example we'll create a temporary database only for the tests.

## File structure

Depending on your use case, you might prefer to use a different library, but if you asked me, I would probably suggest you try **Strawberry**.

Here's a small preview of how you could integrate Strawberry with FastAPI:

```Python hl_lines="3  22  25-26"
{!../../../docs_src/graphql/tutorial001.py!}
```

## Proxy with a stripped path prefix

Having a proxy with a stripped path prefix, in this case, means that you could declare a path at `/app` in your code, but then, you add a layer on top (the proxy) that would put your **FastAPI** application under a path like `/api/v1`.

In this case, the original path `/app` would actually be served at `/api/v1/app`.

Even though all your code is written assuming there's just `/app`.

    Because we are using a relative URL, if your API was located at `https://example.com/`, then it would refer to `https://example.com/token`. But if your API was located at `https://example.com/api/v1/`, then it would refer to `https://example.com/api/v1/token`.

        {
            "detail": [
                {
                    "type": "string_pattern_mismatch",
                    "loc": ["body", "grant_type"],
                    "msg": "String should match pattern 'password'",
                    "input": "incorrect",
                    "ctx": {"pattern": "password"},
                }
            ]
        }
    ) | IsDict(

│   └── main.py
```

In the file `main.py` you have your **FastAPI** app:


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

### Testing file

Then you could have a file `test_main.py` with your tests. It could live on the same Python package (the same directory with a `__init__.py` file):

``` hl_lines="5"
.
├── app
│   ├── __init__.py
│   ├── main.py
│   └── test_main.py
```

#### What is OpenAPI for

The OpenAPI schema is what powers the two interactive documentation systems included.

And there are dozens of alternatives, all based on OpenAPI. You could easily add any of those alternatives to your application built with **FastAPI**.

You could also use it to generate code automatically, for clients that communicate with your API. For example, frontend, mobile or IoT applications.

## Recap, step by step

    # For ORJSONResponse
    "orjson >=3.2.1",
    # To validate email fields
    "email_validator >=2.0.0",
    # Uvicorn with uvloop
    "uvicorn[standard] >=0.12.0",
    # TODO: this should be part of some pydantic optional extra dependencies
    # # Settings management
    # "pydantic-settings >=2.0.0",
    # # Extra Pydantic data types
    # "pydantic-extra-types >=2.0.0",
]

all = [

    This makes sure that if you use a terminal program installed by that package, you use the one from your local environment and not any other that could be installed globally.

### Install requirements using pip

After activating the environment as described above:

<div class="termy">

```console
$ pip install -r requirements.txt

---> 100%

!!! note "Technical Details"
    You could also use `from starlette.requests import Request`.

    **FastAPI** provides it as a convenience for you, the developer. But it comes directly from Starlette.

### Before and after the `response`