code: def test_errors(trivariate_data):
      y, x = trivariate_data
      with pytest.raises(
          ValueError, match="kernel is not a known estimator."
      ):
          phillips_ouliaris(y, x, kernel="fancy-kernel")
      with pytest.raises(
          ValueError, match="Unknown test_type: z-alpha."
      ):
          phillips_ouliaris(y, x, test_type="z-alpha")
  
file_path: arch/arch/tests/unitroot/test_phillips_ouliaris.py
imports: import numpy
  from numpy.testing import assert_allclose
  import pytest
  from statsmodels.iolib.summary import Summary
  from arch.typing import Float64Array, UnitRootTrend
  from arch.unitroot._phillips_ouliaris import CriticalValueWarning, phillips_ouliaris_cv, phillips_ouliaris_pval
  from arch.unitroot.cointegration import phillips_ouliaris
  from arch.utility.timeseries import add_trend
label_desc: Use image node_id 4 for calling a global function with example usage: test_errors(trivariate_data) without return types