LOG4J2-3019: Fix HtmlLayoutTest on Windows

[LF-Lin]

This PR fixes the issue that HtmlLayoutTest.testLayoutWithDatePatternFixedFormat test fails on Windows.

AFAIK, this test only fails in a special case on Windows, that is, the Windows display language and Regional format are inconsistent. For example, my settings are:

Windows display language: zh_CN
Regional format: en_NL

the result will be: [ERROR] HtmlLayoutTest.testLayoutWithDatePatternFixedFormat:245->testLayoutWithDatePatternFixedFormat:277 Incorrect date=<td>02 十一月 2012 21:34:02,123</td>, format=DATE, timezone=GMT+8 ==> expected: <<td>02 Nov 2012 21:32,123</td>> but was: <<td>02 十一月 2012 21:34:02,123</td>>

---

I think the reason is that

• the actual value that generated from layout at line 255 using Locale.getDefault() (zh_CN, which causes 02 十一月),
• the expected value that generated from DateTimeFormatter.ofPattern() at line 269 using Locale.Category.FORMAT (en_NL, which causes 02 Nov).

It is easy to avoid this issue by manually setting the locale argument for DateTimeFormatter.ofPattern(), and the results will use the Locale.getDefault().

[LF-Lin]

Also, I reproduced the result in this issue by adding the following lines in testLayoutWithDatePatternFixedFormat(),

Locale.setDefault(new Locale("en", "NL"));  // en_NL --> 02 Nov
Locale.setDefault(Locale.Category.FORMAT, new Locale("nl", "NL"));  // nl_NL --> 02 nov

the result will be: [ERROR] HtmlLayoutTest.testLayoutWithDatePatternFixedFormat:242->testLayoutWithDatePatternFixedFormat:273 Incorrect date=<td>02 Nov 2012 21:34:02,123</td>, format=DATE, timezone=GMT+8 ==> expected: <<td>02 nov 2012 21:34:02,123</td>> but was: <<td>02 Nov 2012 21:34:02,123</td>>

[garydgregory]

Hi @LF-Lin
Thank you for your PR. In order to make this use-case more obvious in the test, I choose a different implementation; please pull the branch and try your local build. Let us know what your results are.
TY!

[LF-Lin]

Hi @LF-Lin Thank you for your PR. In order to make this use-case more obvious in the test, I choose a different implementation; please pull the branch and try your local build. Let us know what your results are. TY!

Nice implementation. Test passes!

[garydgregory]

Closing, per @LF-Lin 's comment.
TY!