code: def test_dataframe_dummies_mix_default(self, df, sparse, dtype):
      result = get_dummies(df, sparse=sparse, dtype=dtype)
      if sparse:
          arr = SparseArray
          if dtype.kind == "b":
              typ = SparseDtype(dtype, False)
          else:
              typ = SparseDtype(dtype, 0)
      else:
          arr = np.array
          typ = dtype
      expected = DataFrame(
          {
              "C": [1, 2, 3],
              "A_a": arr([1, 0, 1], dtype=typ),
              "A_b": arr([0, 1, 0], dtype=typ),
              "B_b": arr([1, 1, 0], dtype=typ),
              "B_c": arr([0, 0, 1], dtype=typ),
          }
      )
      expected = expected[["C", "A_a", "A_b", "B_b", "B_c"]]
      tm.assert_frame_equal(result, expected)
  
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 13 for calling the TestGetDummies obj's underlying member method code with example usage: obj.test_dataframe_dummies_mix_default(df, sparse, dtype) without return types