Add mypy to pre-commit hooks and configure in pyproject.toml

Co-authored-by: Borda <6035284+Borda@users.noreply.github.com>

Author: Copilot

.pre-commit-config.yaml

@@ -55,3 +55,9 @@ repos:
     rev: v2.4.1
     hooks:
       - id: codespell
+  - repo: https://github.com/pre-commit/mirrors-mypy
+    # Static type checker
+    rev: v1.14.1
+    hooks:
+      - id: mypy
+        additional_dependencies: []

README.md

@@ -49,7 +49,7 @@ You can run the checks manually on all files:
 pre-commit run --all-files
 ```
 
-So far, **there is no types checking with mypy**. See [issue](https://github.com/roboflow-ai/template-python/issues/4).
+We now use **mypy** for type checking. Type hints are enforced and checked automatically via pre-commit hooks.
 
 ### Tests 🧪
 

pyproject.toml

@@ -28,6 +28,7 @@ urls."Homepage" = "https://roboflow.com"
 
 [dependency-groups]
 dev = [
+  "mypy",
   "pre-commit",
   "pytest",
   "twine",
@@ -67,3 +68,9 @@ addopts = [
   "--color=yes",
   "--doctest-modules",
 ]
+
+[tool.mypy]
+python_version = "3.9"
+warn_return_any = true
+warn_unused_configs = true
+disallow_untyped_defs = true

test/test_hello.py

@@ -3,7 +3,7 @@
 from sandbox.hello import hello
 
 
-def test_hello():
+def test_hello() -> None:
     """Test the hello function."""
     res = hello()
     assert res == "World"