code: def test_median_warning_convergence(median, get_mats):
      """Test warning for convergence not reached"""
      n_matrices, n_channels = 3, 2
      mats = get_mats(n_matrices, n_channels, "spd")
      with pytest.warns(UserWarning):
          median(mats, maxiter=0)
  
file_path: pyRiemann/tests/test_utils_median.py
imports: import numpy
  import pytest
  from pytest import approx
  from pyriemann.utils.median import median_euclid, median_riemann
label_desc: Use image node_id 4 for calling a global function with example usage: test_median_warning_convergence(median, get_mats) without return types