Mypy as pre-commit check + api_jws typing (#787)

* feat(mypy): from tox to pre-commit

* fix(mypy): apply mypy fixes

* feat(api_jws): typing

Co-authored-by: JulianMaurin <julian.maurin@backmarket.com>

7 files changed, 51 insertions, 53 deletions

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index d23a169..00b112e 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -34,3 +34,8 @@ repos:
     hooks:
       - id: check-manifest
         args: [--no-build-isolation]
+
+  - repo: https://github.com/pre-commit/mirrors-mypy
+    rev: "v0.971"
+    hooks:
+      - id: mypy
diff --git a/jwt/api_jws.py b/jwt/api_jws.py
index 90206c9..ab8490f 100644
--- a/jwt/api_jws.py
+++ b/jwt/api_jws.py
@@ -1,8 +1,9 @@
+from __future__ import annotations
+
 import binascii
 import json
 import warnings
-from collections.abc import Mapping
-from typing import Any, Dict, List, Optional, Type
+from typing import Any, Type
 
 from .algorithms import (
     Algorithm,
@@ -23,7 +24,7 @@ from .warnings import RemovedInPyjwt3Warning
 class PyJWS:
     header_typ = "JWT"
 
-    def __init__(self, algorithms=None, options=None):
+    def __init__(self, algorithms=None, options=None) -> None:
         self._algorithms = get_default_algorithms()
         self._valid_algs = (
             set(algorithms) if algorithms is not None else set(self._algorithms)
@@ -39,10 +40,10 @@ class PyJWS:
         self.options = {**self._get_default_options(), **options}
 
     @staticmethod
-    def _get_default_options():
+    def _get_default_options() -> dict[str, bool]:
         return {"verify_signature": True}
 
-    def register_algorithm(self, alg_id, alg_obj):
+    def register_algorithm(self, alg_id: str, alg_obj: Algorithm) -> None:
         """
         Registers a new Algorithm for use when creating and verifying tokens.
         """
@@ -55,7 +56,7 @@ class PyJWS:
         self._algorithms[alg_id] = alg_obj
         self._valid_algs.add(alg_id)
 
-    def unregister_algorithm(self, alg_id):
+    def unregister_algorithm(self, alg_id: str) -> None:
         """
         Unregisters an Algorithm for use when creating and verifying tokens
         Throws KeyError if algorithm is not registered.
@@ -69,7 +70,7 @@ class PyJWS:
         del self._algorithms[alg_id]
         self._valid_algs.remove(alg_id)
 
-    def get_algorithms(self):
+    def get_algorithms(self) -> list[str]:
         """
         Returns a list of supported values for the 'alg' parameter.
         """
@@ -96,9 +97,9 @@ class PyJWS:
         self,
         payload: bytes,
         key: str,
-        algorithm: Optional[str] = "HS256",
-        headers: Optional[Dict[str, Any]] = None,
-        json_encoder: Optional[Type[json.JSONEncoder]] = None,
+        algorithm: str | None = "HS256",
+        headers: dict[str, Any] | None = None,
+        json_encoder: Type[json.JSONEncoder] | None = None,
         is_payload_detached: bool = False,
     ) -> str:
         segments = []
@@ -117,7 +118,7 @@ class PyJWS:
                 is_payload_detached = True
 
         # Header
-        header = {"typ": self.header_typ, "alg": algorithm_}  # type: Dict[str, Any]
+        header: dict[str, Any] = {"typ": self.header_typ, "alg": algorithm_}
 
         if headers:
             self._validate_headers(headers)
@@ -165,11 +166,11 @@ class PyJWS:
         self,
         jwt: str,
         key: str = "",
-        algorithms: Optional[List[str]] = None,
-        options: Optional[Dict[str, Any]] = None,
-        detached_payload: Optional[bytes] = None,
+        algorithms: list[str] | None = None,
+        options: dict[str, Any] | None = None,
+        detached_payload: bytes | None = None,
         **kwargs,
-    ) -> Dict[str, Any]:
+    ) -> dict[str, Any]:
         if kwargs:
             warnings.warn(
                 "passing additional kwargs to decode_complete() is deprecated "
@@ -210,9 +211,9 @@ class PyJWS:
         self,
         jwt: str,
         key: str = "",
-        algorithms: Optional[List[str]] = None,
-        options: Optional[Dict[str, Any]] = None,
-        detached_payload: Optional[bytes] = None,
+        algorithms: list[str] | None = None,
+        options: dict[str, Any] | None = None,
+        detached_payload: bytes | None = None,
         **kwargs,
     ) -> str:
         if kwargs:
@@ -227,7 +228,7 @@ class PyJWS:
         )
         return decoded["payload"]
 
-    def get_unverified_header(self, jwt):
+    def get_unverified_header(self, jwt: str | bytes) -> dict:
         """Returns back the JWT header parameters as a dict()
 
         Note: The signature is not verified so the header parameters
@@ -238,7 +239,7 @@ class PyJWS:
 
         return headers
 
-    def _load(self, jwt):
+    def _load(self, jwt: str | bytes) -> tuple[bytes, bytes, dict, bytes]:
         if isinstance(jwt, str):
             jwt = jwt.encode("utf-8")
 
@@ -261,7 +262,7 @@ class PyJWS:
         except ValueError as e:
             raise DecodeError(f"Invalid header string: {e}") from e
 
-        if not isinstance(header, Mapping):
+        if not isinstance(header, dict):
             raise DecodeError("Invalid header string: must be a json object")
 
         try:
@@ -278,16 +279,16 @@ class PyJWS:
 
     def _verify_signature(
         self,
-        signing_input,
-        header,
-        signature,
-        key="",
-        algorithms=None,
-    ):
+        signing_input: bytes,
+        header: dict,
+        signature: bytes,
+        key: str = "",
+        algorithms: list[str] | None = None,
+    ) -> None:
 
         alg = header.get("alg")
 
-        if algorithms is not None and alg not in algorithms:
+        if not alg or (algorithms is not None and alg not in algorithms):
             raise InvalidAlgorithmError("The specified alg value is not allowed")
 
         try:
@@ -299,11 +300,11 @@ class PyJWS:
         if not alg_obj.verify(signing_input, key, signature):
             raise InvalidSignatureError("Signature verification failed")
 
-    def _validate_headers(self, headers):
+    def _validate_headers(self, headers: dict[str, Any]) -> None:
         if "kid" in headers:
             self._validate_kid(headers["kid"])
 
-    def _validate_kid(self, kid):
+    def _validate_kid(self, kid: str) -> None:
         if not isinstance(kid, str):
             raise InvalidTokenError("Key ID header parameter must be a string")
 
diff --git a/jwt/help.py b/jwt/help.py
index 767c323..0c02eb9 100644
--- a/jwt/help.py
+++ b/jwt/help.py
@@ -8,7 +8,7 @@ from . import __version__ as pyjwt_version
 try:
     import cryptography
 except ModuleNotFoundError:
-    cryptography = None  # type: ignore
+    cryptography = None
 
 
 def info() -> Dict[str, Dict[str, str]]:
@@ -29,14 +29,15 @@ def info() -> Dict[str, Dict[str, str]]:
     if implementation == "CPython":
         implementation_version = platform.python_version()
     elif implementation == "PyPy":
+        pypy_version_info = getattr(sys, "pypy_version_info")
         implementation_version = (
-            f"{sys.pypy_version_info.major}."  # type: ignore[attr-defined]
-            f"{sys.pypy_version_info.minor}."
-            f"{sys.pypy_version_info.micro}"
+            f"{pypy_version_info.major}."
+            f"{pypy_version_info.minor}."
+            f"{pypy_version_info.micro}"
         )
-        if sys.pypy_version_info.releaselevel != "final":  # type: ignore[attr-defined]
+        if pypy_version_info.releaselevel != "final":
             implementation_version = "".join(
-                [implementation_version, sys.pypy_version_info.releaselevel]  # type: ignore[attr-defined]
+                [implementation_version, pypy_version_info.releaselevel]
             )
     else:
         implementation_version = "Unknown"
diff --git a/jwt/utils.py b/jwt/utils.py
index b8ad5fa..16cae06 100644
--- a/jwt/utils.py
+++ b/jwt/utils.py
@@ -1,7 +1,7 @@
 import base64
 import binascii
 import re
-from typing import Any, Union
+from typing import Union
 
 try:
     from cryptography.hazmat.primitives.asymmetric.ec import EllipticCurve
@@ -10,7 +10,7 @@ try:
         encode_dss_signature,
     )
 except ModuleNotFoundError:
-    EllipticCurve = Any  # type: ignore
+    EllipticCurve = None
 
 
 def force_bytes(value: Union[str, bytes]) -> bytes:
diff --git a/pyproject.toml b/pyproject.toml
index 8c870eb..f406505 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -2,7 +2,6 @@
 requires = ["setuptools"]
 build-backend = "setuptools.build_meta"
 
-
 [tool.coverage.run]
 parallel = true
 branch = true
@@ -14,8 +13,13 @@ source = ["jwt", ".tox/*/site-packages"]
 [tool.coverage.report]
 show_missing = true
 
-
 [tool.isort]
 profile = "black"
 atomic = true
 combine_as_imports = true
+
+[tool.mypy]
+python_version = 3.7
+ignore_missing_imports = true
+warn_unused_ignores = true
+no_implicit_optional = true
diff --git a/setup.cfg b/setup.cfg
index 9fc9169..434e22c 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -57,7 +57,6 @@ dev =
     types-cryptography>=3.3.21
     pytest>=6.0.0,<7.0.0
     coverage[toml]==5.0.4
-    mypy
     pre-commit
 
 [options.packages.find]
@@ -67,9 +66,3 @@ exclude =
 
 [flake8]
 extend-ignore = E203, E501
-
-[mypy]
-python_version = 3.7
-ignore_missing_imports = true
-warn_unused_ignores = true
-no_implicit_optional = true
diff --git a/tox.ini b/tox.ini
index 3e8513a..07ace11 100644
--- a/tox.ini
+++ b/tox.ini
@@ -48,12 +48,6 @@ commands =
     python -m doctest README.rst
 
 
-[testenv:typing]
-basepython = python3.8
-extras = dev
-commands = mypy jwt
-
-
 [testenv:lint]
 basepython = python3.8
 extras = dev