code: def test_merge_warning(case):
      with pytest.warns(UserWarning, match=r"defined as \"never\""):
          style.merge({"facecolor": "never"}, case)
  
imports: import pytest
  from cartopy.mpl import style
label_desc: Use image node_id 2 for calling a global function with example usage: test_merge_warning(case) without return types