'makemigrations exits when there are no changes to an app.'

def test_makemigrations_no_changes(self):

    out = io.StringIO()
    with self.temporary_migration_module(module='migrations.test_migrations_no_changes'):
        call_command('makemigrations', 'migrations', stdout=out)
    self.assertIn("No    changes    detected    in    app    'migrations'", out.getvalue())
