Error with pyscopg2 and tests

[anonymous]

The test command doesn't work with psycopg2==2.4.2 but does with 2.4.1:

Creating test database for alias 'default'...
Traceback (most recent call last):
  File "manage.py", line 14, in <module>
    execute_manager(settings)
  File "/home/diegueus9/webapps/domicilios/lib/python2.7/site-packages/django/core/management/__init__.py", line 438, in execute_manager
    utility.execute()
  File "/home/diegueus9/webapps/domicilios/lib/python2.7/site-packages/django/core/management/__init__.py", line 379, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/diegueus9/webapps/domicilios/lib/python2.7/site-packages/django/core/management/base.py", line 191, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/home/diegueus9/webapps/domicilios/lib/python2.7/site-packages/django/core/management/base.py", line 220, in execute
    output = self.handle(*args, **options)
  File "/home/diegueus9/webapps/domicilios/lib/python2.7/site-packages/django/core/management/commands/test.py", line 37, in handle
    failures = test_runner.run_tests(test_labels)
  File "/home/diegueus9/webapps/domicilios/lib/python2.7/site-packages/django/test/simple.py", line 359, in run_tests
    old_config = self.setup_databases()
  File "/home/diegueus9/webapps/domicilios/lib/python2.7/site-packages/django/test/simple.py", line 296, in setup_databases
    test_db_name = connection.creation.create_test_db(self.verbosity, autoclobber=not self.interactive)
  File "/home/diegueus9/webapps/domicilios/lib/python2.7/site-packages/django/db/backends/creation.py", line 351, in create_test_db
    self._create_test_db(verbosity, autoclobber)
  File "/home/diegueus9/webapps/domicilios/lib/python2.7/site-packages/django/db/backends/creation.py", line 416, in _create_test_db
    self.set_autocommit()
  File "/home/diegueus9/webapps/domicilios/lib/python2.7/site-packages/django/db/backends/creation.py", line 472, in set_autocommit
    self.connection.connection.autocommit = True
psycopg2.ProgrammingError: autocommit cannot be used inside a transaction

[ampledata]

Going out on a limb and guessing this is due to the transaction control 'overhaul' in Psycopg 2.4.2:

Transaction control has been overhauled: a new connection method set_session() allows setting all the session properties affecting the transactions behaviour: the isolation level but it can also be used to have auto-commit, read-only, and deferrable transactions.

Para: ​http://www.initd.org/psycopg/articles/2011/06/12/psycopg-242-released/

[piro]

The quick fix seems to reverse the test and check for the existence of set_isolation_level before autocommit.

The proper fix is to add a set_autocommit method to the specific database driver.

[piro]

Opened a discussion about the issue in the psycopg ML.

​http://archives.postgresql.org/psycopg/2011-06/msg00028.php

[piro]

Also note that if the exception is raised it means that you have already started a transaction somehow. Asking for autocommit with a transaction already in progress is asking the drivers to be generous and give you a rollback at best. A correct behaviour for a more robust set_autocommit() could be to call connection.rollback() as well.