def METHOD_NAME(df_engine, dummy_df):
    assert np.array_equal(dummy_df.dtypes, ["object", "object", "object", "object", "object"])
    if isinstance(df_engine, DaskEngine):
        dummy_df = df_engine.df_lib.from_pandas(dummy_df, npartitions=1)
    source = wrap_data_source(dummy_df)
    for field in dummy_df.columns:
        assert not is_field_boolean(source, field)