for include_optional in include_optional_dependencies:
        optional_dependencies_group = optional_dependencies.get(include_optional, [])

```Python hl_lines="3"
{!../../../docs_src/app_testing/test_main.py!}
```

...and have the code for the tests just like before.

## Testing: extended example

Now let's extend this example and add more details to see how to test different parts.

### Extended **FastAPI** app file

Let's continue with the same file structure as before:

```
.
├── app
│   ├── __init__.py

```Python
{**note.dict()}
```

`**note.dict()` "unpacks" the key value pairs directly, so, `{**note.dict()}` would be, more or less, a copy of `note.dict()`.

And then, we extend that copy `dict`, adding another key-value pair: `"id": last_record_id`:

```Python
{**note.dict(), "id": last_record_id}
```

So, the final result returned would be something like:

```Python
{

        )
        flat_dependant.path_params.extend(flat_sub.path_params)
        flat_dependant.query_params.extend(flat_sub.query_params)
        flat_dependant.header_params.extend(flat_sub.header_params)
        flat_dependant.cookie_params.extend(flat_sub.cookie_params)
        flat_dependant.body_params.extend(flat_sub.body_params)
        flat_dependant.security_requirements.extend(flat_sub.security_requirements)
    return flat_dependant

!!! tip
    This is a low level extension point.

    If you only need to declare additional responses, a more convenient way to do it is with [Additional Responses in OpenAPI](additional-responses.md){.internal-link target=_blank}.

You can extend the OpenAPI schema for a *path operation* using the parameter `openapi_extra`.

            if route.response_fields:
                responses_from_routes.extend(route.response_fields.values())
            if route.callbacks:
                callback_flat_models.extend(get_fields_from_routes(route.callbacks))
            params = get_flat_params(route.dependant)
            request_fields_from_routes.extend(params)

    flat_models = callback_flat_models + list(

                    current_tags.extend(tags)
                if route.tags:
                    current_tags.extend(route.tags)
                current_dependencies: List[params.Depends] = []
                if dependencies:
                    current_dependencies.extend(dependencies)
                if route.dependencies:
                    current_dependencies.extend(route.dependencies)

    * You can have deeply **nested JSON** objects and have them all validated and annotated.
* **Extensible**:
    * Pydantic allows custom data types to be defined or you can extend validation with methods on a model decorated with the validator decorator.

                    errors=[error], model=RequestErrorModel
                ).errors()
                use_errors.extend(new_errors)
            elif isinstance(error, list):
                use_errors.extend(_normalize_errors(error))
            else:
                use_errors.append(error)
        return use_errors

    def _model_rebuild(model: Type[BaseModel]) -> None:

But you should first read the **Tutorial - User Guide** (what you are reading right now).