mypy: Add type hints

.coveragerc

@@ -11,6 +11,14 @@ source =
 [report]
 show_missing = true
 precision = 2
+omit =
+    src/webob/types.py
+exclude_lines =
+    pragma: no cover
+    @overload
+    if TYPE_CHECKING:
+    if __name__ == .__main__.
+    raise NotImplementedError
 
 [html]
 show_contexts = True

.github/workflows/ci-tests.yml

@@ -120,7 +120,7 @@ jobs:
             - run: tox -e docs
     lint:
         runs-on: ubuntu-22.04
-        name: Lint the package
+        name: Lint and type check the package
         steps:
             - uses: actions/checkout@v4
             - name: Setup python
@@ -129,4 +129,4 @@ jobs:
                   python-version: "3.13"
                   architecture: x64
             - run: pip install tox
-            - run: tox -e lint
+            - run: tox -e lint,mypy

pyproject.toml

@@ -25,3 +25,9 @@ line_length = 88
 force_sort_within_sections = true
 default_section = "THIRDPARTY"
 known_first_party = "webob"
+
+[tool.mypy]
+python_version = 3.9
+strict = true
+warn_unreachable = true
+mypy_path = "$MYPY_CONFIG_FILE_DIR/src"

setup.py

@@ -52,8 +52,11 @@
     license="MIT",
     packages=find_packages("src", exclude=["tests"]),
     package_dir={"": "src"},
+    include_package_data=True,
+    package_data={"webob": ["py.typed"]},
     python_requires=">=3.9.0",
     install_requires=[
+        "typing-extensions>=4.12.0",
         "legacy-cgi>=2.6; python_version>='3.13'",
     ],
     zip_safe=True,