[`fastapi`] Avoid false positive for class dependencies (`FAST003`) (#18271)
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## Summary
Closes #17226.
This PR updates the `FAST003` rule to correctly handle [FastAPI class
dependencies](https://fastapi.tiangolo.com/tutorial/dependencies/classes-as-dependencies/).
Specifically, if a path parameter is declared in either:
- a `pydantic.BaseModel` used as a dependency, or
- the `__init__` method of a class used as a dependency,
then `FAST003` will no longer incorrectly report it as unused.
FastAPI allows a shortcut when using annotated class dependencies -
`Depends` can be called without arguments, e.g.:
```python
class MyParams(BaseModel):
my_id: int
@router.get("/{my_id}")
def get_id(params: Annotated[MyParams, Depends()]): ...
```
This PR ensures that such usage is properly supported by the linter.
Note: Support for dataclasses is not included in this PR. Let me know if
you’d like it to be added.
## Test Plan
Added relevant test cases to the `FAST003.py` fixture.
ruff
e6778637 - [`fastapi`] Avoid false positive for class dependencies (`FAST003`) (#18271)
