16 files declare their use of PathAliasTestTrait in Drupal 9

AliasTest.php in core/modules/path_alias/tests/src/Kernel/AliasTest.php

ContentNegotiationRoutingTest.php in core/tests/Drupal/KernelTests/Core/Routing/ContentNegotiationRoutingTest.php

DbDumpTest.php in core/tests/Drupal/KernelTests/Core/Command/DbDumpTest.php

DisplayFeedTest.php in core/modules/views/tests/src/Functional/Plugin/DisplayFeedTest.php

DisplayFeedTranslationTest.php in core/modules/views/tests/src/Functional/Plugin/DisplayFeedTranslationTest.php

LinkFieldTest.php in core/modules/link/tests/src/Functional/LinkFieldTest.php

LocalePathTest.php in core/modules/locale/tests/src/Functional/LocalePathTest.php

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

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

PathAliasMenuLinkContentTest.php in core/modules/menu_link_content/tests/src/Kernel/PathAliasMenuLinkContentTest.php

PathEncodedTest.php in core/tests/Drupal/FunctionalTests/Routing/PathEncodedTest.php

PathTestBase.php in core/modules/path/tests/src/Functional/PathTestBase.php

RouteCachingNonPathLanguageNegotiationTest.php in core/tests/Drupal/FunctionalTests/Routing/RouteCachingNonPathLanguageNegotiationTest.php

RouteProviderTest.php in core/tests/Drupal/KernelTests/Core/Routing/RouteProviderTest.php

Contains \Drupal\KernelTests\Core\Routing\RouteProviderTest.

ShortcutLinksTest.php in core/modules/shortcut/tests/src/Functional/ShortcutLinksTest.php

UrlAlterFunctionalTest.php in core/modules/path_alias/tests/src/Functional/UrlAlterFunctionalTest.php