Add decorators and tests

.travis.yml

@@ -0,0 +1,7 @@
+language: python
+python:
+ - 3.8
+ - 3.6
+ - 2.7
+install: pip install tox-travis
+script: tox

readonly/cursor.py

@@ -105,8 +105,8 @@ def _last_executed(self):
 
 
 class PatchedCursorWrapper(utils.CursorWrapper):
- def __init__(self, cursor, db):
- self.cursor = ReadOnlyCursorWrapper(cursor, db)
+ def __init__(self, cursor, db,read_only=None):
+ self.cursor = ReadOnlyCursorWrapper(cursor, db, read_only=read_only)
  self.db = db
 
 

readonly/decorators.py

@@ -0,0 +1,49 @@
+from contextlib import contextmanager
+
+from django.db.backends import utils
+
+from readonly.cursor import (
+ PatchedCursorWrapper,
+ PatchedCursorDebugWrapper,
+)
+
+_orig_CursorWrapper = utils.CursorWrapper
+_orig_CursorDebugWrapper = utils.CursorDebugWrapper
+
+
+class ForcedPatchedCursorWrapper(PatchedCursorWrapper):
+ def __init__(self, cursor, db):
+ super(ForcedPatchedCursorWrapper, self).__init__(cursor, db, read_only=True)
+
+
+class ForcedPatchedCursorDebugWrapper(PatchedCursorDebugWrapper):
+ def __init__(self, cursor, db):
+ super(ForcedPatchedCursorDebugWrapper, self).__init__(
+ cursor, db, read_only=True
+ )
+
+
+@contextmanager
+def readonly():
+ old_CursorWrapper = utils.CursorWrapper
+ old_CursorDebugWrapper = utils.CursorDebugWrapper
+ utils.CursorWrapper = ForcedPatchedCursorWrapper
+ utils.CursorDebugWrapper = ForcedPatchedCursorDebugWrapper
+ try:
+ yield
+ finally:
+ utils.CursorWrapper = old_CursorWrapper
+ utils.CursorDebugWrapper = old_CursorDebugWrapper
+
+
+@contextmanager
+def dangerously_enabled():
+ old_CursorWrapper = utils.CursorWrapper
+ old_CursorDebugWrapper = utils.CursorDebugWrapper
+ utils.CursorWrapper = _orig_CursorWrapper
+ utils.CursorDebugWrapper = _orig_CursorDebugWrapper
+ try:
+ yield
+ finally:
+ utils.CursorWrapper = old_CursorWrapper
+ utils.CursorDebugWrapper = old_CursorDebugWrapper

tests/models.py

@@ -0,0 +1,5 @@
+from django.db import models
+
+
+class Widget(models.Model):
+ name = models.CharField(max_length=100)

tests/settings.py

@@ -2,18 +2,18 @@
 
 DB_READ_ONLY_MIDDLEWARE_MESSAGE = False
 SITE_READ_ONLY = False
-DB_READ_ONLY_DATABASES = False
+DB_READ_ONLY_DATABASES = []
 
-DATABASE_ENGINE = "sqlite3"
-
-# Uncomment below to run tests with mysql
-# DATABASE_ENGINE = "django.db.backends.mysql"
-# DATABASE_NAME = "readonly_test"
-# DATABASE_USER = "readonly_test"
-# DATABASE_HOST = "/var/mysql/mysql.sock"
+DATABASES = {
+ "default": {
+ "ENGINE": "django.db.backends.sqlite3",
+ "NAME": ":memory:",
+ },
+}
 
 INSTALLED_APPS = [
  "readonly",
+ "tests",
 ]
 
 MIDDLEWARE = [

tests/test_context_manager.py

@@ -0,0 +1,91 @@
+from django.db import transaction
+from django.db.transaction import TransactionManagementError
+
+from django.test import TestCase
+
+from readonly.decorators import (
+ readonly,
+ dangerously_enabled,
+)
+from readonly.exceptions import DatabaseWriteDenied
+
+from tests.models import Widget
+
+
+class ContextManagerTestCase(TestCase):
+ def _create_obj(self):
+ with transaction.atomic():
+ obj = Widget.objects.create()
+ obj.save()
+
+ def test_normal(self):
+ Widget.objects.count()
+ obj = Widget.objects.create()
+ obj.save()
+
+ def test_readonly_transaction(self):
+ before = Widget.objects.count()
+
+ with readonly():
+ with self.assertRaises(DatabaseWriteDenied):
+ with transaction.atomic():
+ obj = Widget.objects.create()
+ obj.save()
+
+ after = Widget.objects.count()
+ assert after == before
+
+ obj = Widget.objects.create()
+ obj.save()
+
+ after = Widget.objects.count()
+ assert after == before + 1
+
+ def test_readonly(self):
+ Widget.objects.count()
+
+ with readonly():
+ with self.assertRaises(DatabaseWriteDenied):
+ obj = Widget.objects.create()
+ obj.save()
+
+ # TODO: Automatic cancellation of the transaction would simplify
+ # developer use of readonly & DatabaseWriteDenied with foreign code
+ with self.assertRaises(TransactionManagementError):
+ Widget.objects.count()
+
+ def test_nested_readonly_disabled(self):
+ with readonly():
+ with self.assertRaises(DatabaseWriteDenied):
+ self._create_obj()
+ with readonly():
+ with self.assertRaises(DatabaseWriteDenied):
+ self._create_obj()
+ with readonly():
+ with self.assertRaises(DatabaseWriteDenied):
+ self._create_obj()
+
+ Widget.objects.create()
+
+ def test_readonly_enabled(self):
+ with readonly():
+ with dangerously_enabled():
+ self._create_obj()
+
+ def test_nested_readonly_enabled(self):
+ with readonly():
+ with readonly():
+ with dangerously_enabled():
+ with readonly():
+ with dangerously_enabled():
+ with readonly():
+ with self.assertRaises(DatabaseWriteDenied):
+ self._create_obj()
+
+ with self.assertRaises(DatabaseWriteDenied):
+ self._create_obj()
+
+ with self.assertRaises(DatabaseWriteDenied):
+ self._create_obj()
+
+ self._create_obj()

tox.ini

@@ -0,0 +1,18 @@
+[tox]
+envlist = py27-django{18,19,110,111}, py{36,37,38}-django{111,20,21,22,30,31}
+skip_missing_interpreters = True
+
+[testenv]
+commands = python -m django test {posargs}
+setenv =
+ DJANGO_SETTINGS_MODULE = tests.settings
+deps =
+ django18: Django>=1.8,<1.9
+ django19: Django>=1.9,<1.10
+ django110: Django>=1.10,<1.11
+ django111: Django>=1.11,<1.12
+ django20: Django>=2.0,<2.1
+ django21: Django>=2.1,<2.2
+ django22: Django>=2.2,<2.3
+ django30: Django>=3.0,<3.1
+ django31: Django>=3.1,<3.2