Add inline type annotations (#1089)

* crypto: Add type annotations

* Don’t redefine var

mypy complains about the redefinition

* _util: Add type annotations

* rand: Add type annotations

* Prepare package & CI for running mypy

* fix toxenv name

Co-authored-by: Maximilian Hils <github@maximilianhils.com>

.github/workflows/ci.yml

@@ -42,6 +42,7 @@ jobs:
           # Meta
           - {VERSION: "3.9", TOXENV: "check-manifest"}
           - {VERSION: "3.9", TOXENV: "flake8"}
+          - {VERSION: "3.6", TOXENV: "py36-mypy"}
           - {VERSION: "3.9", TOXENV: "docs"}
     name: "${{ matrix.PYTHON.TOXENV }}"
     steps:

MANIFEST.in

@@ -1,5 +1,5 @@
 include             LICENSE MANIFEST.in *.rst tox.ini .coveragerc
-exclude             codecov.yml .readthedocs.yml
+exclude             codecov.yml .readthedocs.yml mypy.ini
 recursive-include   tests           *.py
 recursive-include   doc             *
 prune               doc/_build

mypy.ini

@@ -0,0 +1,24 @@
+[mypy]
+warn_unused_configs = True
+follow_imports = skip
+strict = True
+
+exclude = (?x)(
+    SSL\.py$
+  )
+
+[mypy-OpenSSL.crypto]
+warn_return_any = False
+disallow_any_expr = False
+
+[mypy-OpenSSL.rand]
+warn_return_any = False
+
+[mypy-OpenSSL._util]
+warn_return_any = False
+
+[mypy-cryptography.*]
+ignore_missing_imports = True
+
+[mypy-cffi.*]
+ignore_missing_imports = True

src/OpenSSL/_util.py

@@ -1,9 +1,11 @@
 import os
 import sys
 import warnings
+from typing import Any, Callable, NoReturn, Type, Union
 
 from cryptography.hazmat.bindings.openssl.binding import Binding
 
+StrOrBytesPath = Union[str, bytes, os.PathLike]
 
 binding = Binding()
 ffi = binding.ffi
@@ -16,7 +18,7 @@
 no_zero_allocator = ffi.new_allocator(should_clear_after_alloc=False)
 
 
-def text(charp):
+def text(charp: Any) -> str:
     """
     Get a native string type representing of the given CFFI ``char*`` object.
 
@@ -29,7 +31,7 @@ def text(charp):
     return ffi.string(charp).decode("utf-8")
 
 
-def exception_from_error_queue(exception_type):
+def exception_from_error_queue(exception_type: Type[Exception]) -> NoReturn:
     """
     Convert an OpenSSL library failure into a Python exception.
 
@@ -55,13 +57,13 @@ def exception_from_error_queue(exception_type):
     raise exception_type(errors)
 
 
-def make_assert(error):
+def make_assert(error: Type[Exception]) -> Callable[[bool], Any]:
     """
     Create an assert function that uses :func:`exception_from_error_queue` to
     raise an exception wrapped by *error*.
     """
 
-    def openssl_assert(ok):
+    def openssl_assert(ok: bool) -> None:
         """
         If *ok* is not True, retrieve the error from OpenSSL and raise it.
         """
@@ -71,7 +73,7 @@ def openssl_assert(ok):
     return openssl_assert
 
 
-def path_bytes(s):
+def path_bytes(s: StrOrBytesPath) -> bytes:
     """
     Convert a Python path to a :py:class:`bytes` for the path which can be
     passed into an OpenSSL API accepting a filename.
@@ -88,7 +90,7 @@ def path_bytes(s):
         return b
 
 
-def byte_string(s):
+def byte_string(s: str) -> bytes:
     return s.encode("charmap")
 
 
@@ -99,7 +101,7 @@ def byte_string(s):
 _TEXT_WARNING = "str for {0} is no longer accepted, use bytes"
 
 
-def text_to_bytes_and_warn(label, obj):
+def text_to_bytes_and_warn(label: str, obj: Any) -> Any:
     """
     If ``obj`` is text, emit a warning that it should be bytes instead and try
     to convert it to bytes automatically.