It seems that test_locale_calendar_formatweekday of calendar misses some important inputs:

https://github.com/python/cpython/blob/main/Lib/test/test_calendar.py#L567-L578

Specifically, it does not cover a day under different lengths, ie, several common cases in which 1 <= length <= 10, which can change the weekday formatting.

Linked PRs

• gh-101377: improving test_locale_calendar_formatweekday of calendar #101378
• [3.11] gh-101377: improving test_locale_calendar_formatweekday of calendar (GH-101378) #102713
• [3.10] gh-101377: improving test_locale_calendar_formatweekday of calendar (GH-101378) #102714