Problem/Motivation
When the \Drupal\Tests\Core\Database\ConnectionTest::testFindCallerFromDebugBacktrace() Unit test is performed, the database connection info added is not cleaned up. This can cause problems when additional Unit tests are conducted using the database connection similarly, such as the tests in \Drupal\Tests\Core\DrupalKernel\DiscoverServiceProvidersTest.
Steps to reproduce
Assuming a typical Drupal setup, based on drupal/core-recommended, drupal/core-composer-scaffold and drupal/core-dev. When executing ./vendor/bin/phpunit --configuration web/core --filter 'testFindCallerFromDebugBacktrace$|testDiscoverService' web/core/tests/Drupal/Tests/Core will provide:
PHPUnit 9.6.15 by Sebastian Bergmann and contributors.
Testing /var/www/app/web/core/tests/Drupal/Tests/Core
.EE 3 / 3 (100%)
Time: 00:00.133, Memory: 70.00 MB
There were 2 errors:
1) Drupal\Tests\Core\DrupalKernel\DiscoverServiceProvidersTest::testDiscoverServiceCustom
Error: Class "Drupal\Tests\Core\Database\Stub\Connection" not found
/var/www/app/web/core/lib/Drupal/Core/Database/Database.php:464
/var/www/app/web/core/lib/Drupal/Core/Database/Database.php:195
/var/www/app/web/core/lib/Drupal/Core/Config/BootstrapConfigStorageFactory.php:40
/var/www/app/web/core/lib/Drupal/Core/Config/BootstrapConfigStorageFactory.php:31
/var/www/app/web/core/lib/Drupal/Core/DrupalKernel.php:1409
/var/www/app/web/core/lib/Drupal/Core/DrupalKernel.php:622
/var/www/app/web/core/tests/Drupal/Tests/Core/DrupalKernel/DiscoverServiceProvidersTest.php:31
/var/www/app/vendor/phpunit/phpunit/src/Framework/TestResult.php:728
/var/www/app/vendor/phpunit/phpunit/src/Framework/TestSuite.php:684
/var/www/app/vendor/phpunit/phpunit/src/Framework/TestSuite.php:684
/var/www/app/vendor/phpunit/phpunit/src/TextUI/TestRunner.php:651
/var/www/app/vendor/phpunit/phpunit/src/TextUI/Command.php:144
/var/www/app/vendor/phpunit/phpunit/src/TextUI/Command.php:97
/var/www/app/vendor/bin/phpunit:122
2) Drupal\Tests\Core\DrupalKernel\DiscoverServiceProvidersTest::testDiscoverServiceNoContainerYamls
Error: Class "Drupal\Tests\Core\Database\Stub\Connection" not found
/var/www/app/web/core/lib/Drupal/Core/Database/Database.php:464
/var/www/app/web/core/lib/Drupal/Core/Database/Database.php:195
/var/www/app/web/core/lib/Drupal/Core/Config/BootstrapConfigStorageFactory.php:40
/var/www/app/web/core/lib/Drupal/Core/Config/BootstrapConfigStorageFactory.php:31
/var/www/app/web/core/lib/Drupal/Core/DrupalKernel.php:1409
/var/www/app/web/core/lib/Drupal/Core/DrupalKernel.php:622
/var/www/app/web/core/tests/Drupal/Tests/Core/DrupalKernel/DiscoverServiceProvidersTest.php:52
/var/www/app/vendor/phpunit/phpunit/src/Framework/TestResult.php:728
/var/www/app/vendor/phpunit/phpunit/src/Framework/TestSuite.php:684
/var/www/app/vendor/phpunit/phpunit/src/Framework/TestSuite.php:684
/var/www/app/vendor/phpunit/phpunit/src/TextUI/TestRunner.php:651
/var/www/app/vendor/phpunit/phpunit/src/TextUI/Command.php:144
/var/www/app/vendor/phpunit/phpunit/src/TextUI/Command.php:97
/var/www/app/vendor/bin/phpunit:122
ERRORS!
Tests: 3, Assertions: 1, Errors: 2.
Proposed resolution
One way to solve this is to add a tearDown() function to \Drupal\Tests\Core\Database\ConnectionTest, where the default database connection is removed.
Merge request link
https://git.drupalcode.org/project/drupal/-/merge_requests/6372
Remaining tasks
- Get feedback from community
User interface changes
N.a.
API changes
N.a.
Data model changes
N.a.
Release notes snippet
Added tearDown() to \Drupal\Tests\Core\Database\ConnectionTest to ensure database connection information is removed properly and doesn't affect additional Unit tests.