code: def test_generate_cloudwatch_monitoring_custom_sns():
      """CLI - Terraform Generate Cloudwatch Monitoring with Existing SNS Topic"""
  
      # Test a custom SNS topic name
      CONFIG["clusters"]["test"]["modules"]["cloudwatch_monitoring"] = {
          "enabled": True
      }
      CONFIG["global"]["infrastructure"]["monitoring"][
          "sns_topic_name"
      ] = "unit_test_monitoring"
  
      cluster_dict = common.infinitedict()
      result = monitoring.generate_monitoring(
          "test", cluster_dict, CONFIG
      )
  
      expected_cloudwatch_tf_custom = {
          "source": "./modules/tf_monitoring",
          "sns_topic_arn": "arn:aws:sns:us-west-1:12345678910:unit_test_monitoring",
          "lambda_functions": ["unit-test_test_streamalert_classifier"],
          "kinesis_stream": "${module.kinesis_test.stream_name}",
          "lambda_alarms_enabled": True,
          "kinesis_alarms_enabled": True,
      }
  
      assert_true(result)
      assert_equal(
          cluster_dict["module"]["cloudwatch_monitoring_test"],
          expected_cloudwatch_tf_custom,
      )
  
file_path: streamalert/tests/unit/streamalert_cli/terraform/test_monitoring.py
imports: from mock import patch
  from nose.tools import assert_equal, assert_false, assert_true
  from streamalert_cli.config import CLIConfig
  from streamalert_cli.terraform import common, monitoring
label_desc: Use image node_id 6 for calling a global function with example usage: test_generate_cloudwatch_monitoring_custom_sns() without return types