Fixed #10771 -- added support for using the transaction management functions as context managers in Python 2.5 and above. Thanks to Jacob for help with the docs.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14288 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/modeltests/transactions/tests.py

@@ -1,3 +1,5 @@
+import sys
+
 from django.db import connection, transaction, IntegrityError, DEFAULT_DB_ALIAS
 from django.conf import settings
 from django.test import TransactionTestCase, skipUnlessDBFeature
@@ -5,6 +7,10 @@ from django.test import TransactionTestCase, skipUnlessDBFeature
 from models import Reporter
 
 
+if sys.version_info >= (2, 5):
+    from tests_25 import TransactionContextManagerTests
+
+
 class TransactionTests(TransactionTestCase):
     def create_a_reporter_then_fail(self, first, last):
         a = Reporter(first_name=first, last_name=last)

tests/modeltests/transactions/tests_25.py

@@ -0,0 +1,123 @@
+from __future__ import with_statement
+
+from django.db import connection, transaction, IntegrityError
+from django.test import TransactionTestCase, skipUnlessDBFeature
+
+from models import Reporter
+
+
+class TransactionContextManagerTests(TransactionTestCase):
+    def create_reporter_and_fail(self):
+        Reporter.objects.create(first_name="Bob", last_name="Holtzman")
+        raise Exception
+
+    @skipUnlessDBFeature('supports_transactions')
+    def test_autocommit(self):
+        """
+        The default behavior is to autocommit after each save() action.
+        """
+        with self.assertRaises(Exception):
+            self.create_reporter_and_fail()
+        # The object created before the exception still exists
+        self.assertEqual(Reporter.objects.count(), 1)
+
+    @skipUnlessDBFeature('supports_transactions')
+    def test_autocommit_context_manager(self):
+        """
+        The autocommit context manager works exactly the same as the default
+        behavior.
+        """
+        with self.assertRaises(Exception):
+            with transaction.autocommit():
+                self.create_reporter_and_fail()
+
+        self.assertEqual(Reporter.objects.count(), 1)
+
+    @skipUnlessDBFeature('supports_transactions')
+    def test_autocommit_context_manager_with_using(self):
+        """
+        The autocommit context manager also works with a using argument.
+        """
+        with self.assertRaises(Exception):
+            with transaction.autocommit(using="default"):
+                self.create_reporter_and_fail()
+
+        self.assertEqual(Reporter.objects.count(), 1)
+
+    @skipUnlessDBFeature('supports_transactions')
+    def test_commit_on_success(self):
+        """
+        With the commit_on_success context manager, the transaction is only
+        committed if the block doesn't throw an exception.
+        """
+        with self.assertRaises(Exception):
+            with transaction.commit_on_success():
+                self.create_reporter_and_fail()
+
+        self.assertEqual(Reporter.objects.count(), 0)
+
+    @skipUnlessDBFeature('supports_transactions')
+    def test_commit_on_success_with_using(self):
+        """
+        The commit_on_success context manager also works with a using argument.
+        """
+        with self.assertRaises(Exception):
+            with transaction.commit_on_success(using="default"):
+                self.create_reporter_and_fail()
+
+        self.assertEqual(Reporter.objects.count(), 0)
+
+    @skipUnlessDBFeature('supports_transactions')
+    def test_commit_on_success_succeed(self):
+        """
+        If there aren't any exceptions, the data will get saved.
+        """
+        Reporter.objects.create(first_name="Alice", last_name="Smith")
+        with transaction.commit_on_success():
+            Reporter.objects.filter(first_name="Alice").delete()
+
+        self.assertQuerysetEqual(Reporter.objects.all(), [])
+
+    @skipUnlessDBFeature('supports_transactions')
+    def test_manually_managed(self):
+        """
+        You can manually manage transactions if you really want to, but you
+        have to remember to commit/rollback.
+        """
+        with transaction.commit_manually():
+            Reporter.objects.create(first_name="Libby", last_name="Holtzman")
+            transaction.commit()
+        self.assertEqual(Reporter.objects.count(), 1)
+
+    @skipUnlessDBFeature('supports_transactions')
+    def test_manually_managed_mistake(self):
+        """
+        If you forget, you'll get bad errors.
+        """
+        with self.assertRaises(transaction.TransactionManagementError):
+            with transaction.commit_manually():
+                Reporter.objects.create(first_name="Scott", last_name="Browning")
+
+    @skipUnlessDBFeature('supports_transactions')
+    def test_manually_managed_with_using(self):
+        """
+        The commit_manually function also works with a using argument.
+        """
+        with self.assertRaises(transaction.TransactionManagementError):
+            with transaction.commit_manually(using="default"):
+                Reporter.objects.create(first_name="Walter", last_name="Cronkite")
+
+    @skipUnlessDBFeature('requires_rollback_on_dirty_transaction')
+    def test_bad_sql(self):
+        """
+        Regression for #11900: If a block wrapped by commit_on_success
+        writes a transaction that can't be committed, that transaction should
+        be rolled back. The bug is only visible using the psycopg2 backend,
+        though the fix is generally a good idea.
+        """
+        with self.assertRaises(IntegrityError):
+            with transaction.commit_on_success():
+                cursor = connection.cursor()
+                cursor.execute("INSERT INTO transactions_reporter (first_name, last_name) VALUES ('Douglas', 'Adams');")
+                transaction.set_dirty()
+        transaction.rollback()