Read the docs: https://docs.djangoproject.com/en/1.3/topics/testing/#the-test-database
Apparently you need to add TEST_NAME to your DATABASES in settings.py:
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.mysql',
'NAME': 'mywebsiteurl_django',
'TEST_NAME': 'mywebsiteurl_django_test'
}
}