In PHPUnit test classes, parent::tearDown() should be the last thing done in tearDown() methods.

`WP_UnitTestCase::tearDown()` restores the test environment to the default
conditions, including rolling back the MySQL transaction that the test takes
place in, resetting globals, and unhooking test-specific filters. As such, all
teardown routines for specific tests should happen before the parent class's
`tearDown()` method is called. Failure to do so can cause database locks on
certain configurations, among other problems.

See #31537.

git-svn-id: https://develop.svn.wordpress.org/trunk@31622 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/mail.php

@@ -11,8 +11,8 @@ class Tests_Mail extends WP_UnitTestCase {
 	}
 
 	function tearDown() {
-		parent::tearDown();
 		unset( $_SERVER['SERVER_NAME'] );
+		parent::tearDown();
 	}
 
 	function test_wp_mail_custom_boundaries() {