def METHOD_NAME(get, post, job_template, admin, machine_credential):
    other_cred = Credential(credential_type=machine_credential.credential_type, name="Second", inputs={'username': 'bob'})
    other_cred.save()
    creds = [machine_credential.pk, other_cred.pk]
    url = reverse('api:job_template_launch', kwargs={'pk': job_template.pk})
    resp = post(url, {'credentials': creds}, admin)
    assert 'Cannot assign multiple Machine credentials.' in smart_str(resp.content)