Merge pull request #17 from geoadmin/feat-pb-911-type-checking

PB-911 Introduce type checker

Author: schtibe

Makefile

@@ -35,6 +35,7 @@ PYTHON := $(PIPENV_RUN) python3
 YAPF := $(PIPENV_RUN) yapf
 ISORT := $(PIPENV_RUN) isort
 PYLINT := $(PIPENV_RUN) pylint
+MYPY := $(PIPENV_RUN) mypy
 
 # Find all python files that are not inside a hidden directory (directory starting with .)
 PYTHON_FILES := $(shell find $(APP_SRC_DIR) -type f -name "*.py" -print)
@@ -131,6 +132,9 @@ lint: ## Run the linter on the code base
 	@echo "Run pylint..."
 	LOGGING_CFG=0 $(PYLINT) $(PYTHON_FILES)
 
+.PHONY: type-check
+type-check: ## Run the type-checker mypy
+	$(MYPY) app/
 
 .PHONY: start-local-db
 start-local-db: ## Run the local db as docker container

Pipfile

@@ -26,6 +26,9 @@ factory-boy = "*"
 dill = "*"
 pytest = "*"
 pytest-django = "*"
+mypy = "*"
+types-gevent = "*"
+django-stubs = "~=5.0.4"
 
 [requires]
 python_version = "3.12"

Pipfile.lock

@@ -18,6 +18,9 @@
     - [Debug from vs code](#debug-from-vs-code)
     - [Attach debugger to the tests](#attach-debugger-to-the-tests)
     - [Run tests from within vs code](#run-tests-from-within-vs-code)
+- [Type Checking](#type-checking)
+  - [Mypy](#mypy)
+  - [Library types](#library-types)
 
 ## Summary of the project
 
@@ -108,3 +111,25 @@ settings locally to your workspace:
 
 They can either be in `.vscode/settings.json` or in your workspace settings. Now the tests can be
 run and debugged with the testing tab of vscode (beaker icon).
+
+## Type Checking
+
+### Mypy
+
+Type checking can be done by either calling `mypy` or the make target: 
+
+```sh
+make type-check
+```
+
+This will check all files in the repository.
+
+### Library types
+
+For type-checking, the external library [mypy](https://mypy.readthedocs.io) is being used. See the [type hints cheat sheet](https://mypy.readthedocs.io/en/stable/cheat_sheet_py3.html) for help on getting the types right.
+
+Some 3rd party libraries need to have explicit type stubs installed for the type checker
+to work. Some of them can be found in [typeshed](https://github.com/python/typeshed). Sometimes dedicated
+packages exist, as is the case with [django-stubs](https://pypi.org/project/django-stubs/).
+
+If there aren't any type hints available, they can also be auto-generated with [stubgen](https://mypy.readthedocs.io/en/stable/stubgen.html)

README.md

@@ -23,7 +23,7 @@
 # See https://docs.djangoproject.com/en/5.0/howto/deployment/checklist/
 
 # SECURITY WARNING: keep the secret key used in production secret!
-SECRET_KEY = env('SECRET_KEY', default=None)
+SECRET_KEY = env.str('SECRET_KEY', default=None)
 
 # SECURITY WARNING: don't run with debug turned on in production!
 DEBUG = False
@@ -81,7 +81,7 @@
         'USER': env.str('DB_USER', 'service_control'),
         'PASSWORD': env.str('DB_PW', 'service_control'),
         'HOST': env.str('DB_HOST', 'service_control'),
-        'PORT': env.str('DB_PORT', 5432),
+        'PORT': env.str('DB_PORT', "5432"),
         'TEST': {
             'NAME': env.str('DB_NAME_TEST', 'test_service_control'),
         }

app/config/settings_base.py

@@ -0,0 +1,36 @@
+# basic implementation of the types of django-environ
+# since this package is neither critical nor widely used and rather of simple
+# nature, API wise, it intentionally contains the minimum needed to satisfy
+# the type checker
+import builtins
+from typing import Dict, List
+from _typeshed import Incomplete  # pylint: disable=import-error
+
+
+class Env:
+
+    def __init__(self) -> None:
+        ...
+
+    def __call__(
+        self, var: builtins.str, cast=..., default=..., parse_default: builtins.bool = False
+    ):
+        ...
+
+    def str(self, var: builtins.str, default=..., multiline: builtins.bool = ...) -> builtins.str:
+        ...
+
+    def bool(self, var: builtins.str, default=...) -> builtins.bool:
+        ...
+
+    def int(self, var: builtins.str, default=...) -> builtins.str:
+        ...
+
+    def list(self,
+             var,
+             cast: Incomplete | None = None,
+             default=...) -> List[builtins.str | builtins.int]:
+        ...
+
+    def dict(self, var, cast=..., default=...) -> Dict[builtins.str, builtins.str | builtins.int]:
+        ...

app/stubs/environ/__init__.pyi

@@ -0,0 +1,7 @@
+# Basic implementation of the type for gunicorn used in wsgi.py
+# Since this is the only place used and very likely not subject to change,
+# this stubbing is intentionally very minimal to just satisfy the type checking
+class BaseApplication:
+
+    def run(self):
+        ...

app/stubs/gunicorn/app/base.pyi

@@ -0,0 +1,9 @@
+[mypy]
+# this is important for mypy to find the imports
+mypy_path = ./app,./app/stubs
+plugins =
+    mypy_django_plugin.main
+explicit_package_bases = True
+
+[mypy.plugins.django-stubs]
+django_settings_module = "config.settings_dev"