code: def test_barycenter_weights(get_mats):
      """Test barycenter_weights helper function."""
      n_matrices, n_channels = 4, 3
      covmats = get_mats(n_matrices, n_channels, "spd")
      weights = barycenter_weights(
          covmats, covmats, np.array([[1, 2], [2, 3], [3, 0], [0, 1]])
      )
      assert weights.shape == (n_matrices, 2)
  
imports: from conftest import get_metrics
  import numpy
  from sklearn.neighbors import NearestCentroid
  from pyriemann.datasets import make_gaussian_blobs
  from pyriemann.embedding import SpectralEmbedding, LocallyLinearEmbedding, barycenter_weights, locally_linear_embedding
  import pytest
label_desc: Use image node_id 4 for calling a global function with example usage: test_barycenter_weights(get_mats) without return types