def METHOD_NAME(env, token_client):
    resp = token_client.post(
        '/api/v1/organizers/{}/events/{}/ticketlayouts/'.format(env[0].slug, env[0].slug),
        {
            'name': 'Foo',
            'default': True,
            'layout': [],
        },
        format='json'
    )
    assert resp.status_code == 400
    assert resp.data == {"non_field_errors": ["You cannot have two layouts with default = True"]}