code: def test_create_app_from_env_fails_if_MLFLOW_GATEWAY_CONFIG_is_not_set(
      monkeypatch,
  ):
      monkeypatch.delenv("MLFLOW_GATEWAY_CONFIG", raising=False)
      with pytest.raises(
          MlflowException, match="'MLFLOW_GATEWAY_CONFIG' is not set"
      ):
          create_app_from_env()
  
file_path: mlflow/tests/gateway/test_gateway_app.py
imports: from unittest import mock
  import pytest
  from fastapi.testclient import TestClient
  from mlflow.exceptions import MlflowException
  from mlflow.gateway.app import create_app_from_config, create_app_from_env
  from mlflow.gateway.config import GatewayConfig
  from mlflow.gateway.constants import MLFLOW_GATEWAY_CRUD_ROUTE_BASE, MLFLOW_GATEWAY_ROUTE_BASE
  from tests.gateway.tools import MockAsyncResponse
label_desc: Use image node_id 9 for calling a global function with example usage: test_create_app_from_env_fails_if_MLFLOW_GATEWAY_CONFIG_is_not_set(monkeypatch) without return types