class_docstr: Test common dtype coercion rules between concat and append.
class_docstr_tok: ["Test","common","dtype","coercion","rules","between","concat","and","append","."]
code: def test_concat_categorical_ordered(self):
      # GH 13524
  
      s1 = Series(Categorical([1, 2, np.nan], ordered=True))
      s2 = Series(Categorical([2, 1, 2], ordered=True))
  
      exp = Series(Categorical([1, 2, np.nan, 2, 1, 2], ordered=True))
      tm.assert_series_equal(
          pd.concat([s1, s2], ignore_index=True), exp
      )
      tm.assert_series_equal(s1._append(s2, ignore_index=True), exp)
  
      exp = Series(
          Categorical(
              [1, 2, np.nan, 2, 1, 2, 1, 2, np.nan], ordered=True
          )
      )
      tm.assert_series_equal(
          pd.concat([s1, s2, s1], ignore_index=True), exp
      )
      tm.assert_series_equal(
          s1._append([s2, s1], ignore_index=True), exp
      )
  
imports: import numpy
  import pytest
  import pandas
  from pandas import Categorical, DataFrame, Index, Series
  import pandas._testing
label_desc: Use image node_id 16 for calling the TestConcatAppendCommon obj's underlying member method code with example usage: obj.test_concat_categorical_ordered() without return types