code: def test_get_dummies_raises_on_dtype_object(self, df):
      msg = "dtype=object is not a valid dtype for get_dummies"
      with pytest.raises(ValueError, match=msg):
          get_dummies(df, dtype="object")
  
imports: import re
  import unicodedata
  import numpy
  import pytest
  import pandas.util._test_decorators
  from pandas.core.dtypes.common import is_integer_dtype
  import pandas
  from pandas import ArrowDtype, Categorical, CategoricalDtype, CategoricalIndex, DataFrame, Index, RangeIndex, Series, SparseDtype, get_dummies
  import pandas._testing
  from pandas.core.arrays.sparse import SparseArray
label_desc: Use image node_id 5 for calling the TestGetDummies obj's underlying member method code with example usage: obj.test_get_dummies_raises_on_dtype_object(df) without return types