code: def test_nodata_shadow():
      assert str(NodataShadowWarning()) == (
          "The dataset's nodata attribute is shadowing "
          "the alpha band. All masks will be determined "
          "by the nodata attribute"
      )
  
file_path: rasterio/tests/test_warnings.py
imports: import rasterio
  from rasterio.errors import NodataShadowWarning, NotGeoreferencedWarning
  from affine import Affine
  import pytest
label_desc: Use image node_id 2 for calling a global function with example usage: test_nodata_shadow() without return types