code: def test_invalid_options():
      mod = get_model(univariate=True)
      mod.initialize_known([0], [[0]])
  
      mod.ssm.set_inversion_method(0, solve_lu=True)
      msg = (
          "Singular forecast error covariance matrix detected, but"
          " multivariate filter cannot fall back to univariate"
          " filter when the inversion method is set to anything"
          " other than INVERT_UNIVARIATE or SOLVE_CHOLESKY."
      )
      with pytest.raises(NotImplementedError, match=msg):
          mod.ssm.filter()
  
      mod = get_model(univariate=True)
      mod.initialize_known([0], [[0]])
      mod.ssm.smooth_classical = True
      msg = (
          "Cannot use classical smoothing when the multivariate filter has"
          " fallen back to univariate filtering."
      )
      with pytest.raises(NotImplementedError, match=msg):
          mod.ssm.smooth()
  
      mod = get_model(univariate=True)
      mod.initialize_known([0], [[0]])
      mod.ssm.smooth_alternative = True
      msg = (
          "Cannot use alternative smoothing when the multivariate filter has"
          " fallen back to univariate filtering."
      )
      with pytest.raises(NotImplementedError, match=msg):
          mod.ssm.smooth()
  
file_path: statsmodels/statsmodels/tsa/statespace/tests/test_multivariate_switch_univariate.py
imports: import numpy
  import pytest
  from statsmodels.tsa.statespace import mlemodel, sarimax, structural, varmax, dynamic_factor
  from statsmodels.tsa.statespace.tests.test_impulse_responses import TVSS
  from numpy.testing import assert_allclose
label_desc: Use image node_id 7 for calling a global function with example usage: test_invalid_options() without return types