14 files declare their use of ExpectDeprecationTrait in Drupal 8

ContentEntityBaseUnitTest.php in core/tests/Drupal/Tests/Core/Entity/ContentEntityBaseUnitTest.php

ContextAwarePluginBaseTest.php in core/tests/Drupal/KernelTests/Core/Plugin/Context/ContextAwarePluginBaseTest.php

DeprecationListenerTrait.php in core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php

EntityTestMapFieldResourceTestBase.php in core/modules/system/tests/modules/entity_test/tests/src/Functional/Rest/EntityTestMapFieldResourceTestBase.php

EntityTestResourceTestBase.php in core/modules/system/tests/modules/entity_test/tests/src/Functional/Rest/EntityTestResourceTestBase.php

EntityUnitTest.php in core/tests/Drupal/Tests/Core/Entity/EntityUnitTest.php

ExpectDeprecationTest.php in core/tests/Drupal/Tests/ExpectDeprecationTest.php

FileFieldValidateTest.php in core/modules/file/tests/src/Functional/FileFieldValidateTest.php

LegacyMigrateUrlAliasTest.php in core/modules/path/tests/src/Kernel/Migrate/d6/LegacyMigrateUrlAliasTest.php

LegacyMigrateUrlAliasTest.php in core/modules/path/tests/src/Kernel/Migrate/d7/LegacyMigrateUrlAliasTest.php

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

ReverseProxyMiddlewareTest.php in core/tests/Drupal/Tests/Core/StackMiddleware/ReverseProxyMiddlewareTest.php

SettingsTest.php in core/tests/Drupal/Tests/Core/Site/SettingsTest.php

SqlContentEntityStorageSchemaConverterTestBase.php in core/modules/system/tests/src/Functional/Entity/Update/SqlContentEntityStorageSchemaConverterTestBase.php