code: def test_cov(self):
      cov = Covariance()
      cov.fit(self.X)
      L = cov.components_
      assert_array_almost_equal(
          L.T.dot(L), cov.get_mahalanobis_matrix()
      )
  
imports: import unittest
  import numpy
  import pytest
  from scipy.stats import ortho_group
  from sklearn.datasets import load_iris
  from numpy.testing import assert_array_almost_equal, assert_allclose
  from metric_learn.sklearn_shims import ignore_warnings
  from metric_learn import LMNN, NCA, LFDA, Covariance, MLKR, LSML_Supervised, ITML_Supervised, SDML_Supervised, RCA_Supervised
  from metric_learn._util import components_from_metric
  from metric_learn.exceptions import NonPSDError
label_desc: Use image node_id 2 for calling the TestTransformerMetricConversion obj's underlying member method code with example usage: obj.test_cov() without return types