def METHOD_NAME(self, client, access_token, users):
    document = {
        "username": "user_0",
        "password": "my-long-password",
        "email": "user_create_test@kiwix.org",
        "role": "manager",
    }
    url = "/users/"
    response = client.post(
        url, json=document, headers={"Authorization": access_token}
    )
    assert response.status_code == 400
    response_json = response.get_json()
    assert "error" in response_json
    assert response_json["error"] == "User already exists"