code: def test_diff_period(self):
      # GH#32995 Don't pass an incorrect axis
      pi = date_range("2016-01-01", periods=3).to_period("D")
      df = DataFrame({"A": pi})
  
      result = df.diff(1, axis=1)
  
      expected = (df - pd.NaT).astype(object)
      tm.assert_frame_equal(result, expected)
  
imports: import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Series, Timestamp, date_range
  import pandas._testing
label_desc: Use image node_id 16 for calling the TestDataFrameDiff obj's underlying member method code with example usage: obj.test_diff_period() without return types