Patch includes new statements in test_localecalendars of CalendarTestCase such that coverage of LocaleTextCalendar.formatweekday should improve significantly. 

Feedback is appreciated.

Thanks for working to increase our test coverage, Sean.Fleming!

Looking at the current coverage, the there is one line in LocaleTextCalendar.formatweekday without coverage: http://hg.python.org/cpython/file/e159cb0d955b/Lib/calendar.py#l519.

You add some additional tests, but they are mostly testing some very literal aspects of the implementation rather than the purpose of the function. For example:

+        self.assertRaises(IndexError, calendar.LocaleTextCalendar(locale='').formatweekday, 7, 1 )

It's true that this will raise an IndexError, but formatweekday isn't supposed to be called with these values.

I've added some tests that add coverage for the line that didn't have coverage, while focusing on the purpose of the function, namely to provide an appropriate day name when constrained to various widths.

* The patch passes the full test suite
* The patch passes `make patchcheck`
* The patch results in full coverage for LocaleTextCalendar.formatweekday

Coverage results, before and after:

$ ./python.exe ../coveragepy/ run --pylib --source=calendar Lib/test/regrtest.py test_calendar
[1/1] test_calendar
1 test OK.
nitefly:cpython jesstess$ ./python.exe ../coveragepy/ report --show-missing
Name           Stmts   Miss  Cover   Missing
--------------------------------------------
Lib/calendar     375     54    86%   511, 519, 541, 608-699, 703
$ patch -p1 < issue13330.patch 
patching file Lib/test/test_calendar.py
patching file Misc/ACKS
$ ./python.exe ../coveragepy/ run --pylib --source=calendar Lib/test/regrtest.py test_calendar
[1/1] test_calendar
1 test OK.
nitefly:cpython jesstess$ ./python.exe ../coveragepy/ report --show-missing
Name           Stmts   Miss  Cover   Missing
--------------------------------------------
Lib/calendar     375     53    86%   511, 541, 608-699, 703

(519 was the one line without coverage inside LocaleTextCalendar.formatweekday)

The test depends on the en_US locale. Only existing of POSIX locale is guarantied. The test should be skipped instead of failed if the en_US locale is not available. It would be nice to test also with other locales. For example with de_DE, fr_FR, tr_TR, ps_AF - these locales are used also in other tests.

And it looks that only empty locale works on Windows (issue21731).

The patch needs to be reviewed. If the tests are still relevant and increase coverage, it needs to be converted to a GitHub PR. Otherwise this issue can be closed.

See also issue25528.