code: def test_preserve_category(self):
      # GH 15853
      data = DataFrame({"A": [1, 2], "B": pd.Categorical(["X", "Y"])})
      result = melt(data, ["B"], ["A"])
      expected = DataFrame(
          {
              "B": pd.Categorical(["X", "Y"]),
              "variable": ["A", "A"],
              "value": [1, 2],
          }
      )
  
      tm.assert_frame_equal(result, expected)
  
imports: import re
  import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Index, date_range, lreshape, melt, wide_to_long
  import pandas._testing
label_desc: Use image node_id 15 for calling the TestMelt obj's underlying member method code with example usage: obj.test_preserve_category() without return types