Refactor tests code via Rector, September 2026

Problem/Motivation

Regular Rector run on every test class in core, including modules.

Proposed resolution

Use rector with type coverage on all tests classes in core.

Install rector

$ composer require --dev rector/rector palantirnet/drupal-rector

Configure rector.php file

<?php

declare(strict_types=1);

use Rector\PHPUnit\Set\PHPUnitSetList;
use Rector\DeadCode\Rector\ClassMethod\RemoveDeadStmtRector;
use Rector\DeadCode\Rector\ClassMethod\RemoveUnusedConstructorParamRector;
use Rector\TypeDeclaration\Rector\ClassMethod;

return Rector\Config\RectorConfig::configure()
  ->withBootstrapFiles([
     'vendor/palantirnet/drupal-rector/config/drupal-phpunit-bootstrap-file.php',
  ])
  ->withPaths([
    'core/tests',
    'core/modules/**/tests/src',
  ])
  ->withSkip([
    '*/*ixture*/*',
    '*/Annotation/Doctrine/*',
    RemoveUnusedConstructorParamRector::class => [
      'core/tests/Drupal/Tests/Component/Plugin/Factory/ReflectionFactoryTest.php',
      'core/tests/Drupal/TestTools/TestRunner/Configuration.php',
      'core/tests/Drupal/Tests/Core/Config/Entity/EntityDisplayBaseTest.php',
    ],
    RemoveDeadStmtRector::class => [
      'core/tests/Drupal/Tests/Core/StringTranslation/TranslatableMarkupTest.php',
    ],
  ])
  ->withPreparedSets(
    deadCode: true,
    typeDeclarations: true,
  )
  ->withImportNames(
    importDocBlockNames: false,
    importShortClasses: false,
    removeUnusedImports: false,
  );

Run rector
$ ./vendor/bin/rector

Fix code style
$ composer phpcbf

Update baseline
$ ./vendor/bin/phpstan analyse -c core/phpstan.neon.dist --generate-baseline=core/.phpstan-baseline.php --memory-limit=2G

Then adjust manually any remaining error reported.

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet