Add tox test to check if migrations were missed. (#1081)

* Add tox test to check if migrations were missed.

* Document how to contribute migrations.

Author: n2ygk

docs/contributing.rst

@@ -96,6 +96,24 @@ When deploying your app, don't forget to compile the messages with::
     django-admin compilemessages
 
 
+Migrations
+==========
+
+If you alter any models, a new migration will need to be generated. This step is frequently missed
+by new contributors. You can check if a new migration is needed with::
+
+    tox -e migrations
+
+And, if a new migration is needed, use::
+
+    django-admin makemigrations --settings tests.mig_settings
+
+Auto migrations frequently have ugly names like `0004_auto_20200902_2022`. You can make your migration
+name "better" by adding the `-n name` option::
+
+    django-admin makemigrations --settings tests.mig_settings -n widget
+
+
 Pull requests
 =============
 

tests/mig_settings.py

@@ -0,0 +1,125 @@
+"""
+Django settings for CI testing if migrations have been missed.
+
+Generated by 'django-admin startproject' using Django 4.0.1.
+
+For more information on this file, see
+https://docs.djangoproject.com/en/4.0/topics/settings/
+
+For the full list of settings and their values, see
+https://docs.djangoproject.com/en/4.0/ref/settings/
+"""
+
+from pathlib import Path
+
+
+# Build paths inside the project like this: BASE_DIR / 'subdir'.
+BASE_DIR = Path(__file__).resolve().parent.parent
+
+
+# Quick-start development settings - unsuitable for production
+# See https://docs.djangoproject.com/en/4.0/howto/deployment/checklist/
+
+# SECURITY WARNING: keep the secret key used in production secret!
+SECRET_KEY = "django-insecure-9$j0^ot%41l5r(nj9hg02up-n+$59kld!0%l6pvqbd()u%z2as"
+
+# SECURITY WARNING: don't run with debug turned on in production!
+DEBUG = True
+
+ALLOWED_HOSTS = []
+
+
+# Application definition
+
+INSTALLED_APPS = [
+    "django.contrib.admin",
+    "django.contrib.auth",
+    "django.contrib.contenttypes",
+    "django.contrib.sessions",
+    "django.contrib.messages",
+    "django.contrib.staticfiles",
+    "oauth2_provider",
+]
+
+MIDDLEWARE = [
+    "django.middleware.security.SecurityMiddleware",
+    "django.contrib.sessions.middleware.SessionMiddleware",
+    "django.middleware.common.CommonMiddleware",
+    "django.middleware.csrf.CsrfViewMiddleware",
+    "django.contrib.auth.middleware.AuthenticationMiddleware",
+    "django.contrib.messages.middleware.MessageMiddleware",
+    "django.middleware.clickjacking.XFrameOptionsMiddleware",
+]
+
+
+TEMPLATES = [
+    {
+        "BACKEND": "django.template.backends.django.DjangoTemplates",
+        "DIRS": ["templates"],
+        "APP_DIRS": True,
+        "OPTIONS": {
+            "context_processors": [
+                "django.template.context_processors.debug",
+                "django.template.context_processors.request",
+                "django.contrib.auth.context_processors.auth",
+                "django.contrib.messages.context_processors.messages",
+            ],
+        },
+    },
+]
+
+WSGI_APPLICATION = "tutorial.wsgi.application"
+
+LOGIN_URL = "/admin/login/"
+
+# Database
+# https://docs.djangoproject.com/en/4.0/ref/settings/#databases
+
+DATABASES = {
+    "default": {
+        "ENGINE": "django.db.backends.sqlite3",
+        "NAME": ":memory:",
+    }
+}
+
+
+# Password validation
+# https://docs.djangoproject.com/en/4.0/ref/settings/#auth-password-validators
+
+AUTH_PASSWORD_VALIDATORS = [
+    {
+        "NAME": "django.contrib.auth.password_validation.UserAttributeSimilarityValidator",
+    },
+    {
+        "NAME": "django.contrib.auth.password_validation.MinimumLengthValidator",
+    },
+    {
+        "NAME": "django.contrib.auth.password_validation.CommonPasswordValidator",
+    },
+    {
+        "NAME": "django.contrib.auth.password_validation.NumericPasswordValidator",
+    },
+]
+
+
+# Internationalization
+# https://docs.djangoproject.com/en/4.0/topics/i18n/
+
+LANGUAGE_CODE = "en-us"
+
+TIME_ZONE = "UTC"
+
+USE_I18N = True
+
+USE_TZ = True
+
+
+# Static files (CSS, JavaScript, Images)
+# https://docs.djangoproject.com/en/4.0/howto/static-files/
+
+STATIC_URL = "static/"
+
+# Default primary key field type
+# https://docs.djangoproject.com/en/4.0/ref/settings/#default-auto-field
+
+DEFAULT_AUTO_FIELD = "django.db.models.BigAutoField"

tox.ini

@@ -1,6 +1,7 @@
 [tox]
 envlist =
     flake8,
+    migrations,
     docs,
     py{37,38,39}-dj22,
     py{37,38,39,310}-dj32,
@@ -10,7 +11,7 @@ envlist =
 [gh-actions]
 python =
     3.7: py37
-    3.8: py38, docs, flake8
+    3.8: py38, docs, flake8, migrations
     3.9: py39
     3.10: py310
 
@@ -82,6 +83,13 @@ deps =
     flake8-quotes
     flake8-black
 
+[testenv:migrations]
+setenv =
+    DJANGO_SETTINGS_MODULE = tests.mig_settings
+    PYTHONPATH = {toxinidir}
+    PYTHONWARNINGS = all
+commands = django-admin makemigrations --dry-run --check
+
 [testenv:build]
 deps =
     setuptools>=39.0