Consider altering a column as backward incompatible

* Resolves #9
* With test
* For mysql only currently

django_migration_linter/sql_analyser.py

@@ -50,6 +50,10 @@ migration_tests = (
         'fn': lambda sql, **kw: re.search('RENAME TABLE', sql) or
                 re.search('ALTER TABLE .* RENAME TO', sql),
         'err_msg': 'RENAMING tables'
+    }, {
+        'code': 'ALTER_COLUMN',
+        'fn': lambda sql, **kw: re.search('ALTER TABLE .* MODIFY', sql),
+        'err_msg': 'ALTERING columns'
     }, {
         'code': '',
         'fn': has_default,

tests/fixtures.py

@@ -28,6 +28,8 @@ DROP_COLUMN_PROJECT = os.path.join(
     _FIXTURES_FOLDER, 'test_project_drop_column/')
 RENAME_COLUMN_PROJECT = os.path.join(
     _FIXTURES_FOLDER, 'test_project_rename_column/')
+ALTER_COLUMN_PROJECT = os.path.join(
+    _FIXTURES_FOLDER, 'test_project_alter_column')
 RENAME_TABLE_PROJECT = os.path.join(
     _FIXTURES_FOLDER, 'test_project_rename_table/')
 ADD_NOT_NULL_COLUMN_FOLLOWED_BY_DEFAULT_PROJECT = os.path.join(

tests/functional/test_migration_linter.py

@@ -25,6 +25,17 @@ class BackwardcompatibilityDetectionTest(unittest.TestCase):
             BackwardcompatibilityDetectionTest,
             self).tearDown(*args, **kwargs)
 
+    def _test_linter_finds_errors(self, path, commit_id=None):
+        linter = MigrationLinter(path)
+        linter.lint_all_migrations(git_commit_id=commit_id)
+        self.assertTrue(linter.has_errors)
+
+    def _test_linter_finds_no_errors(self, path, commit_id=None):
+        linter = MigrationLinter(path)
+        linter.lint_all_migrations(git_commit_id=commit_id)
+        self.assertFalse(linter.has_errors)
+
+    # *** Tests ***
     def test_create_table_with_not_null_column(self):
         test_project_path = fixtures.CREATE_TABLE_WITH_NOT_NULL_COLUMN_PROJECT
         self._test_linter_finds_no_errors(test_project_path)
@@ -50,6 +61,10 @@ class BackwardcompatibilityDetectionTest(unittest.TestCase):
             fixtures.ADD_NOT_NULL_COLUMN_FOLLOWED_BY_DEFAULT_PROJECT
         self._test_linter_finds_no_errors(test_project_path)
 
+    def test_detect_alter_column(self):
+        test_project_path = fixtures.ALTER_COLUMN_PROJECT
+        self._test_linter_finds_errors(test_project_path)
+
     def test_no_specify_git_hash(self):
         test_project_path = fixtures.MULTI_COMMIT_PROJECT
         fixtures.prepare_git_project(test_project_path)
@@ -66,13 +81,3 @@ class BackwardcompatibilityDetectionTest(unittest.TestCase):
     #    test_project_path = fixtures.MULTI_COMMIT_PROJECT
     #    fixtures.prepare_git_project(test_project_path)
     #    self._test_linter_finds_no_errors(test_project_path, commit_id='tag1')
-
-    def _test_linter_finds_errors(self, path, commit_id=None):
-        linter = MigrationLinter(path)
-        linter.lint_all_migrations(git_commit_id=commit_id)
-        self.assertTrue(linter.has_errors)
-
-    def _test_linter_finds_no_errors(self, path, commit_id=None):
-        linter = MigrationLinter(path)
-        linter.lint_all_migrations(git_commit_id=commit_id)
-        self.assertFalse(linter.has_errors)

tests/test_project_fixtures/test_project_alter_column/.gitignore

@@ -0,0 +1,3 @@
+*.pyc
+__pycache__/
+*sqlite3

tests/test_project_fixtures/test_project_alter_column/manage.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+import os
+import sys
+
+if __name__ == "__main__":
+    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "test_project_alter_column.settings")
+    try:
+        from django.core.management import execute_from_command_line
+    except ImportError:
+        # The above import may fail for some other reason. Ensure that the
+        # issue is really that Django is missing to avoid masking other
+        # exceptions on Python 2.
+        try:
+            import django
+        except ImportError:
+            raise ImportError(
+                "Couldn't import Django. Are you sure it's installed and "
+                "available on your PYTHONPATH environment variable? Did you "
+                "forget to activate a virtual environment?"
+            )
+        raise
+    execute_from_command_line(sys.argv)

tests/test_project_fixtures/test_project_alter_column/test_app/admin.py

@@ -0,0 +1,3 @@
+from django.contrib import admin
+
+# Register your models here.

tests/test_project_fixtures/test_project_alter_column/test_app/apps.py

@@ -0,0 +1,5 @@
+from django.apps import AppConfig
+
+
+class TestAppConfig(AppConfig):
+    name = 'test_app'

tests/test_project_fixtures/test_project_alter_column/test_app/migrations/0001_initial.py

@@ -0,0 +1,21 @@
+# Generated by Django 2.0.1 on 2018-01-14 12:48
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='A',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('code', models.CharField(max_length=10, null=True)),
+            ],
+        ),
+    ]

tests/test_project_fixtures/test_project_alter_column/test_app/migrations/0002_alter_column.py

@@ -0,0 +1,18 @@
+# Generated by Django 2.0.1 on 2018-01-14 12:48
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('test_app', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='a',
+            name='code',
+            field=models.IntegerField(null=True),
+        ),
+    ]

tests/test_project_fixtures/test_project_alter_column/test_app/models.py

@@ -0,0 +1,4 @@
+from django.db import models
+
+class A(models.Model):
+	code = models.IntegerField(null=True)

tests/test_project_fixtures/test_project_alter_column/test_app/tests.py

@@ -0,0 +1,3 @@
+from django.test import TestCase
+
+# Create your tests here.

tests/test_project_fixtures/test_project_alter_column/test_app/views.py

@@ -0,0 +1,3 @@
+from django.shortcuts import render
+
+# Create your views here.

tests/test_project_fixtures/test_project_alter_column/test_project_alter_column/settings.py

@@ -0,0 +1,120 @@
+"""
+Django settings for test_project_alter_column project.
+
+Generated by 'django-admin startproject' using Django 1.11.6.
+
+For more information on this file, see
+https://docs.djangoproject.com/en/1.11/topics/settings/
+
+For the full list of settings and their values, see
+https://docs.djangoproject.com/en/1.11/ref/settings/
+"""
+
+import os
+
+# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
+BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+
+
+# Quick-start development settings - unsuitable for production
+# See https://docs.djangoproject.com/en/1.11/howto/deployment/checklist/
+
+# SECURITY WARNING: keep the secret key used in production secret!
+SECRET_KEY = 'gtb+mohs%gf0+#fr89vw7e&#edmv=q8!iv+n&j_soawk$tkj3^'
+
+# 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',
+    'test_app'
+]
+
+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',
+]
+
+ROOT_URLCONF = 'test_project_alter_column.urls'
+
+TEMPLATES = [
+    {
+        'BACKEND': 'django.template.backends.django.DjangoTemplates',
+        'DIRS': [],
+        '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 = 'test_project_alter_column.wsgi.application'
+
+
+# Database
+# https://docs.djangoproject.com/en/1.11/ref/settings/#databases
+
+DATABASES = {
+    'default': {
+        'ENGINE': 'django_fake_database_backends.backends.mysql'
+    }
+}
+
+
+# Password validation
+# https://docs.djangoproject.com/en/1.11/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/1.11/topics/i18n/
+
+LANGUAGE_CODE = 'en-us'
+
+TIME_ZONE = 'UTC'
+
+USE_I18N = True
+
+USE_L10N = True
+
+USE_TZ = True
+
+
+# Static files (CSS, JavaScript, Images)
+# https://docs.djangoproject.com/en/1.11/howto/static-files/
+
+STATIC_URL = '/static/'

tests/test_project_fixtures/test_project_alter_column/test_project_alter_column/urls.py

@@ -0,0 +1,21 @@
+"""linter_test_project URL Configuration
+
+The `urlpatterns` list routes URLs to views. For more information please see:
+    https://docs.djangoproject.com/en/1.11/topics/http/urls/
+Examples:
+Function views
+    1. Add an import:  from my_app import views
+    2. Add a URL to urlpatterns:  url(r'^$', views.home, name='home')
+Class-based views
+    1. Add an import:  from other_app.views import Home
+    2. Add a URL to urlpatterns:  url(r'^$', Home.as_view(), name='home')
+Including another URLconf
+    1. Import the include() function: from django.conf.urls import url, include
+    2. Add a URL to urlpatterns:  url(r'^blog/', include('blog.urls'))
+"""
+from django.conf.urls import url
+from django.contrib import admin
+
+urlpatterns = [
+    url(r'^admin/', admin.site.urls),
+]

tests/test_project_fixtures/test_project_alter_column/test_project_alter_column/wsgi.py

@@ -0,0 +1,16 @@
+"""
+WSGI config for linter_test_project project.
+
+It exposes the WSGI callable as a module-level variable named ``application``.
+
+For more information on this file, see
+https://docs.djangoproject.com/en/1.11/howto/deployment/wsgi/
+"""
+
+import os
+
+from django.core.wsgi import get_wsgi_application
+
+os.environ.setdefault("DJANGO_SETTINGS_MODULE", "test_project_alter_column.settings")
+
+application = get_wsgi_application()