code: def test_linalg_warning():
      """Test that warnings are issued when no regularization is applied."""
      pytest.importorskip("sklearn")
      from sklearn.linear_model import Ridge
  
      n_feats, n_targets, n_samples = 5, 60, 50
      X, y = _make_data(n_feats, n_targets, n_samples, tmin, tmax)
      for estimator in (0.0, Ridge(alpha=0.0)):
          rf = ReceptiveField(tmin, tmax, 1.0, estimator=estimator)
          with pytest.warns(
              (RuntimeWarning, UserWarning),
              match="[Singular|scipy.linalg.solve]",
          ):
              rf.fit(y, X)
  
imports: from pathlib import Path
  import numpy
  import pytest
  from numpy import einsum
  from numpy.fft import irfft, rfft
  from numpy.testing import assert_allclose, assert_array_equal, assert_equal
  from mne.decoding import ReceptiveField, TimeDelayingRidge
  from mne.decoding.receptive_field import _SCORERS, _delay_time_series, _delays_to_slice, _times_to_delays
  from mne.decoding.time_delaying_ridge import _compute_corrs, _compute_reg_neighbors
label_desc: Use image node_id 10 for calling a global function with example usage: test_linalg_warning() without return types