Should test262/test/intl402/DateTimeFormat/offset-timezone-no-unicode-minus-sign.js fail ONLY if offset time zones are supported?

[justingrant]

Node 22 added support for offset time zones options like timeZone: '+05:30' in the Intl.DateTimeFormat constructor.

The test test262/test/intl402/DateTimeFormat/offset-timezone-no-unicode-minus-sign.js verifies that the character U+2212 (unicode minus sign) is rejected when present in an offset time zone. But this test has always failed because, prior to Node 22, implementations didn't accept offset time zones at all.

Given that this test failed both before and after implementations introduced offset time zones, it might make it too easy for implementations to simply turn off this test and not notice that their offset time zone implementation doesn't meet the current spec because they accept U+2212 but should not accept it.

Should we change this test to only fail if offset time zones are supported AND the character U+2212 is accepted? This would change this test from "expected fail" to "expected pass" for pre-offset-time-zone-accepting implementations, which might make it easier for implementations to notice that their offset time zone implementation is not spec-compliant.

FYI @ptomato

[ptomato]

Seems like a good suggestion to me. We don't usually write tests like this in test262 but the argument that it will otherwise never get taken off of implementations' skip lists is convincing to me.