code: def test_downscale_smoothing_factor(self):
      config = AutoscalingConfig(
          min_replicas=0,
          max_replicas=100,
          target_num_ongoing_requests_per_replica=1,
          downscale_smoothing_factor=0.5,
      )
      num_replicas = 10
  
      # Should use upscale smoothing factor of 1 (default)
      num_ongoing_requests = [4.0] * num_replicas
      desired_num_replicas = _calculate_desired_num_replicas(
          autoscaling_config=config,
          current_num_ongoing_requests=num_ongoing_requests,
      )
      assert 39 <= desired_num_replicas <= 41  # 10 + (40 - 10) = 40
  
      # Should use downscale smoothing factor of 0.5
      num_ongoing_requests = [0.25] * num_replicas
      desired_num_replicas = _calculate_desired_num_replicas(
          autoscaling_config=config,
          current_num_ongoing_requests=num_ongoing_requests,
      )
      assert 5 <= desired_num_replicas <= 8
  
imports: import sys
  import numpy
  import pytest
  from ray.serve._private.autoscaling_policy import AutoscalingPolicyManager
  from ray.serve._private.constants import CONTROL_LOOP_PERIOD_S
  from ray.serve.autoscaling_policy import _calculate_desired_num_replicas
  from ray.serve.config import AutoscalingConfig
label_desc: Use image node_id 6 for calling the TestCalculateDesiredNumReplicas obj's underlying member method code with example usage: obj.test_downscale_smoothing_factor() without return types