Index: tests/phpunit/includes/bootstrap.php
===================================================================
--- tests/phpunit/includes/bootstrap.php	(revision 40052)
+++ tests/phpunit/includes/bootstrap.php	(working copy)
@@ -3,6 +3,12 @@
  * Installs WordPress for running the tests and loads WordPress and the test libraries
  */
 
+/**
+ * Migration fixer for PHPUnit 6
+ */
+if ( class_exists( 'PHPUnit\Runner\Version' ) ) {
+	require_once dirname( __FILE__ ) . '/phpunit6-compat.php';
+}
 
 $config_file_path = dirname( dirname( __FILE__ ) );
 if ( ! file_exists( $config_file_path . '/wp-tests-config.php' ) ) {
Index: tests/phpunit/includes/phpunit6-compat.php
===================================================================
--- tests/phpunit/includes/phpunit6-compat.php	(nonexistent)
+++ tests/phpunit/includes/phpunit6-compat.php	(working copy)
@@ -0,0 +1,35 @@
+<?php
+
+if ( class_exists( 'PHPUnit\Runner\Version' ) && version_compare( PHPUnit\Runner\Version::id(), '6.0', '>=' ) ) {
+	class_alias( 'PHPUnit\Framework\TestCase', 'PHPUnit_Framework_TestCase' );
+	class_alias( 'PHPUnit\Framework\Exception', 'PHPUnit_Framework_Exception' );
+	class_alias( 'PHPUnit\Framework\ExpectationFailedException', 'PHPUnit_Framework_ExpectationFailedException' );
+	class_alias( 'PHPUnit\Framework\Error\Notice', 'PHPUnit_Framework_Error_Notice' );
+	class_alias( 'PHPUnit\Framework\Test', 'PHPUnit_Framework_Test' );
+	class_alias( 'PHPUnit\Framework\Warning', 'PHPUnit_Framework_Warning' );
+	class_alias( 'PHPUnit\Framework\AssertionFailedError', 'PHPUnit_Framework_AssertionFailedError' );
+	class_alias( 'PHPUnit\Framework\TestSuite', 'PHPUnit_Framework_TestSuite' );
+	class_alias( 'PHPUnit\Framework\TestListener', 'PHPUnit_Framework_TestListener' );
+	class_alias( 'PHPUnit\Util\GlobalState', 'PHPUnit_Util_GlobalState' );
+	class_alias( 'PHPUnit\Util\Getopt', 'PHPUnit_Util_Getopt' );
+
+	class PHPUnit_Util_Test extends PHPUnit\Util\Test {
+		public static function getTickets( $className, $methodName ) {
+			$annotations = self::parseTestMethodAnnotations(
+			$className, $methodName
+			);
+
+			$tickets = array();
+
+			if (isset($annotations['class']['ticket'])) {
+				$tickets = $annotations['class']['ticket'];
+			}
+
+			if (isset($annotations['method']['ticket'])) {
+				$tickets = array_merge($tickets, $annotations['method']['ticket']);
+			}
+
+			return array_unique($tickets);
+		}
+	}
+}