text: """
  Tests for arviz.utils
  """
  import pytest
  from arviz.utils import _var_names
  
  
  @pytest.mark.parametrize(
      "var_names_expected", [("mu", ["mu"]), (None, None), (["mu", "tau"], ["mu", "tau"])]
  )
  def test_var_names(var_names_expected):
      """Test var_name handling"""
      var_names, expected = var_names_expected
      assert _var_names(var_names) == expected
  