6 files declare their use of ContentEntityBaseMockableClass

ContentEntityNormalizerTest.php in core/modules/serialization/tests/src/Unit/Normalizer/ContentEntityNormalizerTest.php
ContentTranslationManageAccessCheckTest.php in core/modules/content_translation/tests/src/Unit/Access/ContentTranslationManageAccessCheckTest.php
EntityAdapterUnitTest.php in core/tests/Drupal/Tests/Core/Entity/TypedData/EntityAdapterUnitTest.php
EntityNormalizerTest.php in core/modules/serialization/tests/src/Unit/Normalizer/EntityNormalizerTest.php
SqlContentEntityStorageTest.php in core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageTest.php
TwigSandboxTest.php in core/tests/Drupal/Tests/Core/Template/TwigSandboxTest.php

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