Type hints across main flask-wtf codebase

[princerb]

Type hints across the main flask-wtf codebase to enhance type safety and maintainability. This is the part 1, if acceptable, I will add the rest that includes type hints in recaptcha codebase.

Checklist:

• [x] Add Type Hints to main codebase.
• [x] Add Type hints to recaptcha codebase
• [x] Add Type hints to tests
• [x] Apply modern X | Y syntax
• [ ] Update pyproject.toml adding mypy and pyright cfgs
• [x] Add typing requirements
• [ ] Edit tox env
• [ ] Update CI env

[davidism]

• Use from __future__ import annotations at the top of every file that has annotations
• Use import typing as t and import collections.abc as cabc rather than importing many names
• Use | syntax such as int | None instead of Optional[int]
• Add types to tests as well as src
• Add the following mypy and pyright config to pyproject.toml. Add it after the tool.coverage section:

  [tool.mypy]
  python_version = "3.9"
  files = ["src", "tests"]
  show_error_codes = true
  pretty = true
  strict = true
  
  [tool.pyright]
  pythonVersion = "3.9"
  include = ["src", "tests"]
  typeCheckingMode = "standard"
  

• You also need to add the typing requirements lock, tox env, and CI env, see Flask-SQLAlchemy-Lite for reference: https://github.com/pallets-eco/flask-sqlalchemy-lite/tree/0b182c5e3488d0971a8798184b8be650c2d09330

[davidism]

You need to set up pre-commit, or pull the fixes that pre-commit adds, instead of force pushing. pre-commit install --install-hooks

[princerb]

After adding mypy and pyright, I'm seeing more type errors, primarily due to type compatibility issues with the main WTForms library. Should I try to resolve these type conflicts, or would it be better to adjust the type checking settings? I'm open to any suggestions on how to handle this.

[princerb]

@davidism Any ideas you can suggest?

[davidism]

Don't adjust the type checking settings. MyPy strict must pass. Pyright standard should pass, but can be lowered to basic if absolutely necessary. Pyright --verifytypes must pass. You can add specific ignore comments in if it's otherwise impossible to satisfy MyPy. If WTForms annotations need fixes, submit a fix there as well. But I can't say more without specific examples.