Add infrastructure for type checking in Python code

Type annotations are provided in the project's Python code to indicate the types of objects. Previously no
infrastructure was provided to leverage or validate these annotations.

A task is added here to allow contributors to easily check for typing problems using the mypy tool.

A new job is added to the "Check Python" GitHub Actions workflow to run the task on every push or pull request that
modifies relevant files.

Author: per1234

.github/workflows/check-python-task.yml

@@ -15,6 +15,8 @@ on:
       - "**/poetry.lock"
       - "**/pyproject.toml"
       - "**/setup.cfg"
+      - ".mypy.ini"
+      - "mypy.ini"
       - "Taskfile.ya?ml"
       - "**/tox.ini"
       - "**.py"
@@ -25,6 +27,8 @@ on:
       - "**/poetry.lock"
       - "**/pyproject.toml"
       - "**/setup.cfg"
+      - ".mypy.ini"
+      - "mypy.ini"
       - "Taskfile.ya?ml"
       - "**/tox.ini"
       - "**.py"
@@ -120,3 +124,34 @@ jobs:
 
       - name: Check formatting
         run: git diff --color --exit-code
+
+  types:
+    needs: run-determination
+    if: needs.run-determination.outputs.result == 'true'
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Install Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+
+      - name: Install Poetry
+        run: pip install poetry
+
+      - name: Install Task
+        uses: arduino/setup-task@v1
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          version: 3.x
+
+      - name: Check types
+        uses: liskin/gh-problem-matcher-wrap@v3
+        with:
+          linters: mypy
+          run: task python:check-types

Taskfile.yml

@@ -16,6 +16,7 @@ tasks:
       - task: markdown:lint
       - task: npm:validate
       - task: poetry:validate
+      - task: python:check-types
       - task: python:lint
       - task: python:test
 
@@ -233,6 +234,16 @@ tasks:
         poetry run \
           coverage report
 
+  python:check-types:
+    desc: Check types in Python files
+    deps:
+      - task: poetry:install-deps
+    cmds:
+      - |
+        poetry run \
+          mypy \
+            .
+
   # Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/assets/check-python-task/Taskfile.yml
   python:format:
     desc: Format Python files

poetry.lock

@@ -18,6 +18,7 @@ flake8 = "6.1.0"
 pep8-naming = "0.13.3"
 pytest = "7.4.3"
 pytest-mock = "3.12.0"
+mypy = "1.7.1"
 
 [build-system]
 requires = ["poetry-core"]