<i18n dev> RFR: 8369590: LocaleEnhanceTest has incorrectly passing test case [v3]

[Naoto Sato]

On Tue, 14 Oct 2025 21:11:39 GMT, Justin Lu <jlu at openjdk.org> wrote:

>> This PR corrects _test/jdk/java/util/Locale/LocaleEnhanceTest.java_, which has two test cases under `testBuilderSetLanguageTag()` which accidentally pass. One checks that Locale.setLanguageTag(String) throws ILE for duplicate extensions and the other for duplicate U-extension keys. The test cases are updated to actually test the provided code. When the test cases are fixed, they now fail.
>> 
>> Fixing the behavior to match the expectation of those test cases is consistent with the specification.
>> 
>> From `Locale.forLanguageTag(String)`,
>> 
>>> 
>>>      * <p>If the specified language tag contains any ill-formed subtags,
>>>      * the first such subtag and all following subtags are ignored.  Compare
>>>      * to {@link Locale.Builder#setLanguageTag(String)} which throws an exception
>>>      * in this case.
>> 
>> and the RFC specification
>> 
>>> Each singleton subtag MUST appear at most one time in each tag
>>>        (other than as a private use subtag).  That is, singleton subtags
>>>        MUST NOT be repeated.  For example, the tag "en-a-bbb-a-ccc" is
>>>        invalid because the subtag 'a' appears twice.
>> 
>> Since duplicate extensions (and Unicode keys/attributes) are invalid, throwing `IllformedLocaleException` in (the strict) `Locale.Builder` and ignoring in (the lenient) `Locale.forLanguageTag` for such tags would be appropriate. This PR updates the implementation as such.
>
> Justin Lu has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Align setExtension(char, String) + spec updates

LGTM. Glad to see those test clean-ups, especiallly getting rid of the proprietary test framework

-------------

Marked as reviewed by naoto (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/27775#pullrequestreview-3341556118