Add more pytest idiom to io.excel testing

[simonjayhawkins]

master tracker for follow-ups to #26755 and related PRs

• use pytest.importorskip/not use the class structure Split test_excel into submodule #26755 (review)

• location of fixtures Split test_excel into submodule #26755 (review)

• imports and try/except TST/CLN: declass smaller test files in tests\io\excel #26764 (review)

• xlwt dependency/create a write_ext fixture TST/CLN: declass smaller test files in tests\io\excel #26764 (review)

• use of safe_import in pytest.param TST: return pytest MarkDecorator from td.skip_if_no #26735 (comment) TST/CLN: engine fixture for tests/io/excel/test_readers.py #27139

• parametrisation of write tests Move ExcelWriter Tests #26740 (review)

• consider patch filename extension Move ExcelWriter Tests #26740 (review)

• align the engine / ext usage in the Writer classes Excel Tests Continued Fixture Cleanup #26662 (review)

• get rid of the None engine tests and just have a separate test that ensures how that gets bound to a particular engine Excel Tests Continued Fixture Cleanup #26662 (comment) (get rid of the None engine tests and just have a separate test that ensures how that gets bound to a particular engine #26662 (comment) #28749)

• engine and ext injected into tests Excel Tests Continued Fixture Cleanup #26662 (comment) Eliminated _WriterBase class, removed unused fixtures from methods in pandas/io/excel/test_writers.py #28753

• add some doc-strings Remove SharedItems from test_excel #26579 (review)

• test_bad_engine_raises shouldn't parametrised Fixturize Test Excel #26543 (comment) (get rid of the None engine tests and just have a separate test that ensures how that gets bound to a particular engine #26662 (comment) #28749)

• Eliminate _WriterBase class Eliminated _WriterBase class, removed unused fixtures from methods in pandas/io/excel/test_writers.py #28753

cc @WillAyd

[WillAyd]

Thanks for adding this!

[WillAyd]

Some of these I think should be pretty easy, particularly:

• use of safe_import in pytest.param TST: return pytest MarkDecorator from td.skip_if_no #26735 (comment)
• get rid of the None engine tests and just have a separate test that ensures how that gets bound to a particular engine Excel Tests Continued Fixture Cleanup #26662 (comment)
• add some doc-strings Remove SharedItems from test_excel #26579 (review)
• test_bad_engine_raises shouldn't parametrised Fixturize Test Excel #26543 (comment)
• Eliminate _WriterBase class

So adding "good first issue" label to see if the community would like to pitch in on those

[awa5114]

Where is the _WriterBase class? I cannot find it...

[simonjayhawkins]

pandas/pandas/tests/io/excel/test_writers.py

Line 224 in f8225bc

class _WriterBase: