code: def test_cov_nearest(self):
      x = self.x
      res_r = self.res
      y = cov_nearest(x, method="nearest")
      # print np.max(np.abs(x - y))
      assert_almost_equal(y, res_r.mat, decimal=3)
      d = norm_f(x, y)
      assert_allclose(d, res_r.normF, rtol=0.001)
  
      y = cov_nearest(x, method="clipped")
      # print np.max(np.abs(x - y))
      assert_almost_equal(y, res_r.mat, decimal=2)
      d = norm_f(x, y)
      assert_allclose(d, res_r.normF, rtol=0.15)
  
imports: import warnings
  import numpy
  from numpy.testing import assert_almost_equal, assert_allclose
  import scipy.sparse
  import pytest
  from statsmodels.stats.correlation_tools import corr_nearest, corr_clipped, cov_nearest, _project_correlation_factors, corr_nearest_factor, _spg_optim, corr_thresholded, cov_nearest_factor_homog, FactoredPSDMatrix
  from statsmodels.tools.testing import Holder
label_desc: Use image node_id 2 for calling the TestCovPSD obj's underlying member method code with example usage: obj.test_cov_nearest() without return types