code: def test_rolling_trend(
      window_length, gap, expected_vals, window_series_pd
  ):
      primitive_instance = RollingTrend(
          window_length=window_length, gap=gap
      )
  
      actual_vals = primitive_instance(
          window_series_pd.index, window_series_pd.values
      )
  
      pd.testing.assert_series_equal(
          pd.Series(expected_vals), pd.Series(actual_vals)
      )
  
file_path: featuretools/featuretools/tests/primitive_tests/aggregation_primitive_tests/test_rolling_primitive.py
imports: import numpy
  import pandas
  import pytest
  from featuretools.primitives import RollingCount, RollingMax, RollingMean, RollingMin, RollingOutlierCount, RollingSTD, RollingTrend
  from featuretools.primitives.standard.transform.time_series.utils import apply_rolling_agg_to_series
  from featuretools.tests.primitive_tests.utils import get_number_from_offset
label_desc: Use image node_id 8 for calling a global function with example usage: test_rolling_trend(window_length, gap, expected_vals, window_series_pd) without return types