Since PHPUnit 6 Parallel:Split-Tests has stopped working

[CABellamy]

Splitting tests now fails since the upgrade to PHPUnit6. Running taskSplitTestsByGroups throws the following error:

ERROR: Interface 'PHPUnit_Framework_Test' not found
in /project/vendor/codeception/base/src/Codeception/TestInterface.php:7

Call Stack:
0.0010 356648 1. {main}() /ProjectDir/ui-tests/vendor/consolidation/robo/robo:0
0.0103 949600 2. Robo\Runner->execute() /ProjectDir/ui-tests/vendor/consolidation/robo/robo:20
0.0265 1649712 3. Robo\Runner->run() /ProjectDir/ui-tests/vendor/consolidation/robo/src/Runner.php:111
0.1245 4442688 4. Symfony\Component\Console\Application->run() /ProjectDir/ui-tests/vendor/consolidation/robo/src/Runner.php:157
0.1419 4443520 5. Symfony\Component\Console\Application->doRun() /ProjectDir/ui-tests/vendor/symfony/console/Application.php:130
0.1421 4443520 6. Symfony\Component\Console\Application->doRunCommand() /ProjectDir/ui-tests/vendor/symfony/console/Application.php:223
0.1458 4470032 7. Symfony\Component\Console\Command\Command->run() /ProjectDir/ui-tests/vendor/symfony/console/Application.php:887
0.1476 4482768 8. Consolidation\AnnotatedCommand\AnnotatedCommand->execute() /ProjectDir/ui-tests/vendor/symfony/console/Command/Command.php:264
0.1480 4559112 9. Consolidation\AnnotatedCommand\CommandProcessor->process() /ProjectDir/ui-tests/vendor/consolidation/annotated-command/src/AnnotatedCommand.php:394
0.1480 4559168 10. Consolidation\AnnotatedCommand\CommandProcessor->validateRunAndAlter() /ProjectDir/ui-tests/vendor/consolidation/annotated-command/src/CommandProcessor.php:119
0.1493 4574088 11. Consolidation\AnnotatedCommand\CommandProcessor->runCommandCallback() /ProjectDir/ui-tests/vendor/consolidation/annotated-command/src/CommandProcessor.php:153
0.1494 4575160 12. call_user_func_array:{/ProjectDir/ui-tests/vendor/consolidation/annotated-command/src/CommandProcessor.php:207}() /ProjectDir/ui-tests/vendor/consolidation/annotated-command/src/CommandProcessor.php:207
0.1494 4575568 13. Gaming\Codeception\Robo->parallelSplitTests() /ProjectDir/ui-tests/vendor/consolidation/annotated-command/src/CommandProcessor.php:207
0.1496 4576000 14. Robo\Collection\CollectionBuilder->run() /ProjectDir/ui-tests/vendor/gaming/codeception/src/Robo.php:43
0.1500 4583928 15. Robo\Collection\CollectionBuilder->runTasks() /ProjectDir/ui-tests/vendor/consolidation/robo/src/Collection/CollectionBuilder.php:413
0.1500 4583928 16. Codeception\Task\SplitTestsByGroupsTask->run() /ProjectDir/ui-tests/vendor/consolidation/robo/src/Collection/CollectionBuilder.php:428
0.1575 5114592 17. Codeception\Test\Loader->loadTests() /ProjectDir/ui-tests/vendor/codeception/robo-paracept/src/SplitTestsByGroups.php:78
0.1575 5114592 18. Codeception\Test\Loader->loadTest() /ProjectDir/ui-tests/vendor/codeception/base/src/Codeception/Test/Loader.php:123
0.1576 5114616 19. Codeception\Test\Loader->loadTests() /ProjectDir/ui-tests/vendor/codeception/base/src/Codeception/Test/Loader.php:113
0.1699 5414104 20. Codeception\Test\Loader\Cest->loadTests() /ProjectDir/ui-tests/vendor/codeception/base/src/Codeception/Test/Loader.php:135
0.1721 5503680 21. spl_autoload_call() /ProjectDir/ui-tests/vendor/codeception/base/src/Codeception/Test/Loader/Cest.php:95
0.1721 5503808 22. Composer\Autoload\ClassLoader->loadClass() /ProjectDir/ui-tests/vendor/codeception/base/src/Codeception/Test/Loader/Cest.php:95
0.1721 5503968 23. Composer\Autoload\includeFile() /ProjectDir//ui-tests/vendor/composer/ClassLoader.php:322
0.1726 5549408 24. include('/ProjectDir/ui-tests/vendor/codeception/base/src/Codeception/Test/Cest.php') /ProjectDir/ui-tests/vendor/composer/ClassLoader.php:440
0.1726 5549408 25. spl_autoload_call() /ProjectDir/ui-tests/vendor/codeception/base/src/Codeception/Test/Cest.php:16
0.1726 5549536 26. Composer\Autoload\ClassLoader->loadClass() /ProjectDir/ui-tests/vendor/codeception/base/src/Codeception/Test/Cest.php:16
0.1727 5549696 27. Composer\Autoload\includeFile() /ProjectDir/ui-tests/vendor/composer/ClassLoader.php:322
0.1731 5567384 28. include('/ProjectDir/ui-tests/vendor/codeception/base/src/Codeception/Test/Test.php') /ProjectDir/ui-tests/vendor/composer/ClassLoader.php:440
0.1747 5590664 29. spl_autoload_call() /ProjectDir/ui-tests/vendor/codeception/base/src/Codeception/Test/Test.php:17
0.1747 5590800 30. Composer\Autoload\ClassLoader->loadClass() /ProjectDir/ui-tests/vendor/codeception/base/src/Codeception/Test/Test.php:17
0.1748 5590960 31. Composer\Autoload\includeFile() /ProjectDir/ui-tests/vendor/composer/ClassLoader.php:322
0.1750 5592464 32. include('/ProjectDir/ui-tests/vendor/codeception/base/src/Codeception/TestInterface.php') /ProjectDir/ui-tests/vendor/composer/ClassLoader.php:440

Oddly enough taskSplitTestFilesByGroups works fine.

[maxgorovenko]

Use this header for your RoboFile

<?php
require_once 'vendor/autoload.php';
require_once 'vendor/codeception/codeception/autoload.php';