'Tests --plan output of showmigrations command without migrations'

@override_settings(MIGRATION_MODULES={'migrations': 'migrations.test_migrations_empty'})
def test_showmigrations_plan_no_migrations(self):

    out = io.StringIO()
    call_command('showmigrations', format='plan', stdout=out)
    self.assertEqual('', out.getvalue().lower())
    out = io.StringIO()
    call_command('showmigrations', format='plan', stdout=out, verbosity=2)
    self.assertEqual('', out.getvalue().lower())
