TST: Add additional test for future warning when call Series.str.cat(Series.str) (#47755)
TST: Add additional test for future warning when call Series.str.cat(Series.str) (#47755)

* fix 28277

* fix typo

* add test

* Update pandas/tests/strings/test_cat.py

Co-authored-by: Matthew Roeschke <a890f767f8f4088da51818dce97c2cb936b19031@gmail.com>

* fix pep 8 issue, change comment symbol

Co-authored-by: Matthew Roeschke <a890f767f8f4088da51818dce97c2cb936b19031@gmail.com>
pandas-dev/pandas,datapythonista/pandas,pandas-dev/pandas,pandas-dev/pandas,datapythonista/pandas,datapythonista/pandas,pandas-dev/pandas,datapythonista/pandas