Add mypy checks

.github/workflows/python-tests.yml

@@ -22,6 +22,7 @@ jobs:
           pip install --progress-bar off .[lint]
       - run: flake8 . --show-source
       - run: black --check .
+      - run: mypy .
   test:
     runs-on: ubuntu-latest
     steps:

DEVELOPMENT.md

@@ -1,6 +1,6 @@
 # Developers Guide
 
-## Building source and running dashboard
+## Building source and running dashboard server
 
 ### Building TypeScript files
 
@@ -39,9 +39,9 @@ $ optuna-dashboard sqlite:///db.sqlite3
 
 ## Submitting patches
 
-Before you submitting patches, I recommend you to run tests, linters and auto-formatters.
+To approve your patch, you need to pass following tests, lint checks.
 
-### Running Python tests
+### Running Python unit tests
 
 ```
 $ python setup.py test
@@ -52,11 +52,13 @@ Ran 4 tests in 0.004s
 OK
 ```
 
-### Linters
+### Linters (flake8, black and mypy)
 
 ```
+$ pip install .[lint]
 $ flake8
 $ black --check .
+$ mypy .
 ```
 
 ### Auto-formatting TypeScript files (by prettier)
@@ -68,7 +70,6 @@ $ npm run fmt
 ### Auto-formatting Python files (by black)
 
 ```
-$ pip install .[lint]
 $ black .
 ```
 
@@ -78,7 +79,7 @@ $ black .
 The release process is fully automated by GitHub Actions.
 GitHub Actions will be automatically building TypeScript, packaging Python distributions and uploading to PyPI after you push the git tag.
 
-1. Replace 'optuna_dashboard.version.__version__' to the next version.
+1. Replace `optuna_dashboard.version.__version__` to the next version.
 2. Create a git tag (e.g. `$ git tag v0.X.Y`).
 3. Push the tag to GitHub (e.g. `$ git push origin v0.X.Y`)
 

setup.py

@@ -7,13 +7,13 @@ from importlib.machinery import SourceFileLoader
 BASE_PATH = os.path.dirname(__file__)
 
 
-def get_long_description():
+def get_long_description() -> str:
     readme_filepath = os.path.join(BASE_PATH, "README.md")
     with open(readme_filepath) as f:
         return f.read()
 
 
-def get_version():
+def get_version() -> int:
     version_filepath = os.path.join(BASE_PATH, "optuna_dashboard", "version.py")
     module_name = "version"
     target_module = types.ModuleType(module_name)
@@ -34,7 +34,7 @@ setup(
     packages=find_packages(),
     install_requires=["optuna", "bottle"],
     extras_require={
-        "lint": ["black", "flake8"],
+        "lint": ["black", "flake8", "mypy"],
         "release": ["wheel", "twine"],
     },
     package_data={"optuna_dashboard": ["public/*"]},