gh-118948: add support for ISO 8601 basic format to datetime

[picnixz]

In addition to date and datetime, datetime.time also supports ISO 8601 basic format (the rationale is to make it consistent).

• Issue: Add ISO Basic format support to datetime.isoformat() and date.isoformat() #118948

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📚 Documentation preview 📚: https://cpython-previews--120553.org.readthedocs.build/

[StanFromIreland]

It needs some polishing and simplification in my opinion, especially tests, but looks very good in general :-)

[StanFromIreland]

I feel like there has to be a better way to do this (It could also automatically convert it to basic so we don't have to enter both by hand), a helper function would cut down the amount of lines. (Well, it wouldn't increase.)

[picnixz]

This would be out of scope for the PR and in this case, explicit is likely better than implicit IMO.

[StanFromIreland]

Out of scope is subjective, you pretty much doubled the amount of tests. I guess it could be a follow up pr. (I don't mind doing it)

def assertIsoFormats(self, t, expected):
    self.assertEqual(t.isoformat(), expected)
    expected_basic = expected_standard.replace("-", "").replace(":", "")
    self.assertEqual(t.isoformat(basic=True), expected_basic)

Four lines to save 40ish.

explicit is likely better than implicit IMO.

Any specific reason, for readability?

[picnixz]

Any specific reason, for readability?

Yes, and for tracking bugs in this case. However, if we want to assert the ISO format differently, we should do it in a refactoring PR and not in this one. The ISO format is not the only whose checks could be refactored in some sense IMO.

[picnixz]

This would be out of scope for the PR and in this case, explicit is likely better than implicit IMO.

[StanFromIreland]

I guess we can leave refactoring for later. LGTM :-)