code: def test_invalid_engine(self, grouper, method):
      df = DataFrame({"A": ["a", "b", "a", "b"], "B": range(4)})
      with pytest.raises(ValueError, match="engine must be either"):
          getattr(grouper(df).ewm(com=1.0), method)(engine="foo")
  
imports: import numpy
  import pytest
  from pandas.errors import NumbaUtilError
  import pandas.util._test_decorators
  from pandas import DataFrame, Series, option_context, to_datetime
  import pandas._testing
label_desc: Use image node_id 1 for calling the TestEWM obj's underlying member method code with example usage: obj.test_invalid_engine(grouper, method) without return types