12 files declare their use of MemoryBackend in Zircon Profile 8

AssetResolverTest.php in core/tests/Drupal/Tests/Core/Asset/AssetResolverTest.php

Contains \Drupal\Tests\Core\Asset\AssetResolverTest.

BackendChainImplementationUnitTest.php in core/tests/Drupal/Tests/Core/Cache/BackendChainImplementationUnitTest.php

Contains \Drupal\Tests\Core\Cache\BackendChainImplementationUnitTest.

BackendChainUnitTest.php in core/modules/system/src/Tests/Cache/BackendChainUnitTest.php

Contains \Drupal\system\Tests\Cache\BackendChainUnitTest.

ChainedFastBackendTest.php in core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendTest.php

Contains \Drupal\Tests\Core\Cache\ChainedFastBackendTest.

FileNormalizeTest.php in core/modules/hal/src/Tests/FileNormalizeTest.php

Contains \Drupal\hal\Tests\FileNormalizeTest.

MemoryBackendUnitTest.php in core/modules/system/src/Tests/Cache/MemoryBackendUnitTest.php

Contains \Drupal\system\Tests\Cache\MemoryBackendUnitTest.

NormalizerTestBase.php in core/modules/hal/src/Tests/NormalizerTestBase.php

Contains \Drupal\hal\Tests\NormalizerTestBase.

PluginTestBase.php in core/modules/system/src/Tests/Plugin/PluginTestBase.php

Contains \Drupal\system\Tests\Plugin\PluginTestBase.

RendererBubblingTest.php in core/tests/Drupal/Tests/Core/Render/RendererBubblingTest.php

Contains \Drupal\Tests\Core\Render\RendererBubblingTest.

RendererTestBase.php in core/tests/Drupal/Tests/Core/Render/RendererTestBase.php

Contains \Drupal\Tests\Core\Render\RendererTestBase.

RouteProviderTest.php in core/modules/system/src/Tests/Routing/RouteProviderTest.php

Contains \Drupal\system\Tests\Routing\RouteProviderTest.

StorageComparer.php in core/lib/Drupal/Core/Config/StorageComparer.php

Contains \Drupal\Core\Config\StorageComparer.