code: def test_all_zero_coefs(self):
      alphas = np.array([256, 128, 96, 64, 48])
  
      with pytest.warns(
          UserWarning,
          match="all coefficients are zero, consider decreasing alpha.",
      ):
          _, coxnet = self._fit(
              l1_ratio=0.9, alphas=alphas, alpha_min_ratio=0.001
          )
      assert_array_almost_equal(
          coxnet.coef_, np.zeros((30, 5), dtype=float)
      )
  
imports: from dataclasses import dataclass
  from os.path import dirname, join
  from typing import Optional
  import numpy
  from numpy.testing import assert_array_almost_equal
  import pandas
  import pytest
  from sklearn.exceptions import ConvergenceWarning
  from sklearn.pipeline import make_pipeline
  from sksurv.datasets import get_x_y, load_breast_cancer
  from sksurv.linear_model.coxnet import CoxnetSurvivalAnalysis
  from sksurv.preprocessing import OneHotEncoder
  from sksurv.testing import FixtureParameterFactory
  from sksurv.util import Surv
label_desc: Use image node_id 6 for calling the TestCoxnetSurvivalAnalysis obj's underlying member method code with example usage: obj.test_all_zero_coefs() without return types