Improvements to encoded character formatting tests.

In `sanitize_title_with_dashes()` and `sanitize_user()` tests, we break large
test methods into smaller ones in order to isolate those that actually describe
the bug being reported in ticket #10823. The unit tests that are continuing to
fail have been attached as a patch to that ticket.

See #30284.

git-svn-id: https://develop.svn.wordpress.org/trunk@30515 602fd350-edb4-49c9-b593-d223f7449a82
Remove failing test for unimplemented `wp_mail()` enhancement.

The removed test has been added as a patch to the original ticket, #15448.

Props MikeHansenMe.
See #30284.

git-svn-id: https://develop.svn.wordpress.org/trunk@30516 602fd350-edb4-49c9-b593-d223f7449a82
Remove skipped tests for unimplemented JS plural functions.

The tests have been added as a patch for the original ticket, #22229.

Props MikeHansenMe.
See #22229.

git-svn-id: https://develop.svn.wordpress.org/trunk@30517 602fd350-edb4-49c9-b593-d223f7449a82
Remove skipped tests for `WP_Export_Query`.

These tests have been added as a patch to the ticket where the new
functionality was originally proposed, #22435.

See #30284.

git-svn-id: https://develop.svn.wordpress.org/trunk@30518 602fd350-edb4-49c9-b593-d223f7449a82
Remove failing test in the `hooks` group.

The removed test has been added as a patch to #21169.

Props MikeHansenMe.
See #30284.

git-svn-id: https://develop.svn.wordpress.org/trunk@30519 602fd350-edb4-49c9-b593-d223f7449a82
Remove failing assertions from `is_serialized()` tests.

They have been moved to new test methods, which have been attached as a patch
to the ticket #9930.

See #30284.

git-svn-id: https://develop.svn.wordpress.org/trunk@30520 602fd350-edb4-49c9-b593-d223f7449a82
Remove failing `is_textdomain_loaded()` test.

The removed test has been added as a patch to the original ticket, #21319.

Props MikeHansenMe.
See #30284.

git-svn-id: https://develop.svn.wordpress.org/trunk@30521 602fd350-edb4-49c9-b593-d223f7449a82
Remove failing test related to `wp_unique_post_slug()`.

The test has been added as a patch to #18962.

See #30284.

git-svn-id: https://develop.svn.wordpress.org/trunk@30522 602fd350-edb4-49c9-b593-d223f7449a82
Remove failing test related to `wp_list_pages()`.

The test has been added as a patch to #27326.

Props MikeHansenMe.
See #30284.

git-svn-id: https://develop.svn.wordpress.org/trunk@30523 602fd350-edb4-49c9-b593-d223f7449a82
Remove failing test related to the 'offset' param of `WP_Query`.

This test has been added as a patch to #18897.

Props MikeHansenMe.
See #30284.

git-svn-id: https://develop.svn.wordpress.org/trunk@30524 602fd350-edb4-49c9-b593-d223f7449a82
Repair the `seems_utf8()` tests that use Big5 encoding.

* Provide sample data that is actually encoded in Big5.
* Do some actual assertions against that data.

Props akumria.
Fixes #30455.

git-svn-id: https://develop.svn.wordpress.org/trunk@30525 602fd350-edb4-49c9-b593-d223f7449a82
Stop checking Trac to skip tests against open tickets.

In general, skipped tests should live only in patches, which are committed at
the same time that the corresponding bug is fixed. In cases where it's
necessary to skip a test, use `markTestSkipped()` to declare this fact
explicitly.

We continue to check Trac when using `WP_UnitTestCase` to run non-core tests.

See #30284.

git-svn-id: https://develop.svn.wordpress.org/trunk@30526 602fd350-edb4-49c9-b593-d223f7449a82