def test_iir_params_output_sos_warning(sample_input):
    """Test that providing iir_params with output='sos' raises a warning and modifies the output."""
    n_chans = 8
    sfreq = 100
    iir_params = {"output": "sos"}

    with pytest.warns(UserWarning,
                      match="It is not possible to use second-order section"):
        layer = FilterBankLayer(
            n_chans=n_chans,
            sfreq=sfreq,
            band_filters=None,
            method="iir",
            iir_params=iir_params
        )

    assert layer.a_list is not None, "Filters should be initialized."
    assert layer.b_list is not None, "Filters should be initialized."

    assert layer.a_list[0].dtype == torch.float64, "Filter coefficients should be float64."
Test that providing iir_params with output='sos' raises a warning and modifies the output.
test/unit_tests/models/test_modules.py