Add pre-commit and mypy config files

.pre-commit-config.yaml

@@ -0,0 +1,24 @@
+repos:
+  - repo: "meta"
+    hooks:
+      - id: "check-hooks-apply"
+      - id: "check-useless-excludes"
+
+  - repo: "https://github.com/pre-commit/pre-commit-hooks"
+    rev: "v5.0.0"
+    hooks:
+      - id: "check-added-large-files"
+      - id: "check-merge-conflict"
+      - id: "check-yaml"
+
+  - repo: "https://github.com/astral-sh/ruff-pre-commit"
+    rev: "v0.9.2"
+    hooks:
+      - id: "ruff"
+        args: ["--fix"]
+
+  - repo: "https://github.com/psf/black-pre-commit-mirror"
+    rev: "24.10.0"
+    hooks:
+      - id: "black"
+        language_version: "python3.11"

package/__main__.py

@@ -2,7 +2,7 @@
 from ._version import __version__
 
 
-def main():
+def main() -> int:
     import argparse
 
     parser = argparse.ArgumentParser(prog="Squarer of ints")
@@ -14,6 +14,7 @@ def main():
     )
     args = parser.parse_args()
     print(f"Square of {args.x} is {square(args.x)}")
+    return 0
 
 
 if __name__ == "__main__":

pyproject.toml

@@ -50,3 +50,15 @@ ignore = []
 line-length = 88
 target-version = ["py39"]
 extend-exclude = "doc"
+
+[tool.mypy]
+warn_return_any = "True"
+warn_unused_configs = "True"
+strict_optional = "True"
+ignore_missing_imports = "True"
+disallow_any_unimported = "True"
+check_untyped_defs = "True"
+disallow_untyped_defs = "True"
+no_implicit_optional = "True"
+show_error_codes = "True"
+warn_unused_ignores = "True"

test_package.py

@@ -6,5 +6,5 @@
     "x,res",
     [(1, 1), (2, 4), (-1, 1), (0, 0)],
 )
-def test_square(x, res):
+def test_square(x: int, res: int) -> None:
     assert square(x) == res