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_concatlike_datetimetz_short(self, tz):
      # GH#7795
      ix1 = pd.date_range(
          start="2014-07-15", end="2014-07-17", freq="D", tz=tz
      )
      ix2 = pd.DatetimeIndex(["2014-07-11", "2014-07-21"], tz=tz)
      df1 = DataFrame(0, index=ix1, columns=["A", "B"])
      df2 = DataFrame(0, index=ix2, columns=["A", "B"])
  
      exp_idx = pd.DatetimeIndex(
          [
              "2014-07-15",
              "2014-07-16",
              "2014-07-17",
              "2014-07-11",
              "2014-07-21",
          ],
          tz=tz,
      ).as_unit("ns")
      exp = DataFrame(0, index=exp_idx, columns=["A", "B"])
  
      tm.assert_frame_equal(df1._append(df2), exp)
      tm.assert_frame_equal(pd.concat([df1, df2]), exp)
  
imports: import numpy
  import pytest
  import pandas
  from pandas import Categorical, DataFrame, Index, Series
  import pandas._testing
label_desc: Use image node_id 6 for calling the TestConcatAppendCommon obj's underlying member method code with example usage: obj.test_concatlike_datetimetz_short(tz) without return types