code: def test_covmat(self):
      cov, nobs = self.cov, self.nobs
      # from Stata 14
      p_chi2 = 0.4837049015162541
      # df = 6
      chi2 = 5.481422374989864
  
      cov_null = np.array([[30, 15, 0], [15, 20, 0], [0, 0, 10]])
      stat, pv = smmv.test_cov(cov, nobs, cov_null)
      assert_allclose(stat, chi2, rtol=1e-7)
      assert_allclose(pv, p_chi2, rtol=1e-6)
  
file_path: statsmodels/statsmodels/stats/tests/test_multivariate.py
imports: import numpy
  from numpy.testing import assert_allclose, assert_equal
  from statsmodels.stats import weightstats
  import statsmodels.stats.multivariate
  from statsmodels.stats.multivariate import confint_mvmean_fromstats
  from statsmodels.tools.testing import Holder
label_desc: Use image node_id 5 for calling the TestCovStructure obj's underlying member method code with example usage: obj.test_covmat() without return types