from django.core.exceptions import ImproperlyConfigured
from django.db.utils import load_backend
from django.test import SimpleTestCase
from django.test.utils import str_prefix
from django.utils import six


class TestLoadBackend(SimpleTestCase):
    def test_load_backend_invalid_name(self):
        msg = str_prefix(
            "'foo' isn't an available database backend.\n"
            "Try using 'django.db.backends.XXX', where XXX is one of:\n"
            "    %(_)s'mysql', %(_)s'oracle', %(_)s'postgresql_psycopg2', %(_)s'sqlite3'\n"
            "Error was: No module named %%s"
        ) % "foo.base" if six.PY2 else "'foo'"
        with self.assertRaisesMessage(ImproperlyConfigured, msg):
            load_backend('foo')