Add mypy strict typing (#140)

* No errors with mypy --strict

* Apply ruff formatting

* Add py.typed file

* Make it more modern

* Add strict mode to mypy

* Use --with instead of --from

---------

Co-authored-by: Marcelo Trylesinski <marcelotryle@gmail.com>

.github/workflows/main.yml

@@ -28,7 +28,7 @@ jobs:
  run: uv sync --python ${{ matrix.python-version }} --frozen
 
  - name: Run linters
- run: scripts/lint
+ run: scripts/check
 
  - name: Run tests
  run: scripts/test

.gitignore

@@ -89,6 +89,7 @@ coverage.xml
 *.py,cover
 .hypothesis/
 .pytest_cache/
+.ruff_cache/
 cover/
 
 # Translations

multipart/decoders.py

@@ -1,9 +1,22 @@
 import base64
 import binascii
-from io import BufferedWriter
+from typing import TYPE_CHECKING
 
 from .exceptions import DecodeError
 
+if TYPE_CHECKING: # pragma: no cover
+ from typing import Protocol, TypeVar
+
+ _T_contra = TypeVar("_T_contra", contravariant=True)
+
+ class SupportsWrite(Protocol[_T_contra]):
+ def write(self, __b: _T_contra) -> object: ...
+
+ # No way to specify optional methods. See
+ # https://github.com/python/typing/issues/601
+ # close() [Optional]
+ # finalize() [Optional]
+
 
 class Base64Decoder:
  """This object provides an interface to decode a stream of Base64 data. It
@@ -34,7 +47,7 @@ class Base64Decoder:
  :param underlying: the underlying object to pass writes to
  """
 
- def __init__(self, underlying: BufferedWriter):
+ def __init__(self, underlying: "SupportsWrite[bytes]") -> None:
  self.cache = bytearray()
  self.underlying = underlying
 
@@ -67,9 +80,9 @@ def write(self, data: bytes) -> int:
  # Get the remaining bytes and save in our cache.
  remaining_len = len(data) % 4
  if remaining_len > 0:
- self.cache = data[-remaining_len:]
+ self.cache[:] = data[-remaining_len:]
  else:
- self.cache = b""
+ self.cache[:] = b""
 
  # Return the length of the data to indicate no error.
  return len(data)
@@ -112,7 +125,7 @@ class QuotedPrintableDecoder:
  :param underlying: the underlying object to pass writes to
  """
 
- def __init__(self, underlying: BufferedWriter) -> None:
+ def __init__(self, underlying: "SupportsWrite[bytes]") -> None:
  self.cache = b""
  self.underlying = underlying