code: def test_cloudwatch_agent_update_without_change_head_node(
      ssm_client_stub, ec2_client_stub
  ):
      # create test cluster head node ID and an associated cloudwatch helper
      node_id = "i-abc"
      is_head_node = True
      cloudwatch_helper = helpers.get_cloudwatch_helper(node_id)
  
      # given a directive to check for the Unified CloudWatch Agent status...
      # expect CloudWatch Agent is installed
      stubs.get_ec2_cwa_installed_tag_true(ec2_client_stub, node_id)
  
      # given a directive to update a cluster CloudWatch Agent Config without any
      # change...
      # expect the stored the CloudWatch Agent Config is same as local config
      cw_ssm_param_name = helpers.get_ssm_param_name(
          cloudwatch_helper.cluster_name, "agent"
      )
      stubs.get_param_ssm_same(
          ssm_client_stub, cw_ssm_param_name, cloudwatch_helper, "agent"
      )
  
      # given our mocks and the same cloudwatch agent config as input...
      # expect no update performed on CloudWatch Agent Config
      cloudwatch_helper._update_cloudwatch_config("agent", is_head_node)
  
imports: import copy
  from unittest.mock import Mock, patch
  import pytest
  from click.exceptions import ClickException
  import ray.tests.aws.utils.helpers
  import ray.tests.aws.utils.stubs
  from ray.autoscaler._private.aws.config import DEFAULT_AMI, _configure_subnet, _get_subnets_or_die, bootstrap_aws, log_to_cli
  from ray.autoscaler._private.aws.node_provider import AWSNodeProvider
  from ray.autoscaler._private.providers import _get_node_provider
  from ray.tests.aws.utils.constants import AUX_SG, AUX_SUBNET, CUSTOM_IN_BOUND_RULES, DEFAULT_CLUSTER_NAME, DEFAULT_INSTANCE_PROFILE, DEFAULT_KEY_PAIR, DEFAULT_LT, DEFAULT_SG, DEFAULT_SG_AUX_SUBNET, DEFAULT_SG_DUAL_GROUP_RULES, DEFAULT_SG_WITH_NAME, DEFAULT_SG_WITH_NAME_AND_RULES, DEFAULT_SG_WITH_RULES, DEFAULT_SG_WITH_RULES_AUX_SUBNET, DEFAULT_SUBNET
label_desc: Use image node_id 19 for calling a global function with example usage: test_cloudwatch_agent_update_without_change_head_node(ssm_client_stub, ec2_client_stub) without return types