def METHOD_NAME(self):
    C = np.zeros((6,6))
    K = np.random.random()
    mu = np.random.random()
    C[:3,:3] = K-2*mu/3
    C[:3,:3] += 2*np.eye(3)*mu
    C[3:,3:] = mu*np.eye(3)
    output = calc_elastic_constants(C)
    self.assertAlmostEqual(K, output['bulk_modulus'])
    self.assertAlmostEqual(mu, output['shear_modulus'])
    self.assertAlmostEqual(
        np.linalg.norm(C-get_elastic_tensor_by_orientation([[1, 0, 0], [0, 0, -1], [0, 1, 0]], C)), 0
    )