43 files declare their use of Yaml

add_pagination_heading.php in core/modules/views/tests/fixtures/update/add_pagination_heading.php
Test fixture.
AutoconfigurationTest.php in core/tests/Drupal/KernelTests/Core/DependencyInjection/AutoconfigurationTest.php
AutowireTest.php in core/tests/Drupal/KernelTests/Core/DependencyInjection/AutowireTest.php
ckeditor5-3222756.php in core/modules/ckeditor5/tests/fixtures/update/ckeditor5-3222756.php
Test fixture.
ckeditor5-3259593.php in core/modules/ckeditor5/tests/fixtures/update/ckeditor5-3259593.php
Test fixture.
ckeditor5-3396628.php in core/modules/ckeditor5/tests/fixtures/update/ckeditor5-3396628.php
Test fixture.
ConfigController.php in core/modules/config/src/Controller/ConfigController.php
ConfigExportUITest.php in core/modules/config/tests/src/Functional/ConfigExportUITest.php
ConfigImportUITest.php in core/modules/config/tests/src/Functional/ConfigImportUITest.php
ConfigInstallProfileUnmetDependenciesTest.php in core/modules/config/tests/src/Functional/ConfigInstallProfileUnmetDependenciesTest.php
ConfigManager.php in core/lib/Drupal/Core/Config/ConfigManager.php
ConfigSingleExportForm.php in core/modules/config/src/Form/ConfigSingleExportForm.php
ConfigSingleImportExportTest.php in core/modules/config/tests/src/Functional/ConfigSingleImportExportTest.php
ConfigSingleImportForm.php in core/modules/config/src/Form/ConfigSingleImportForm.php
DistributionProfileTest.php in core/tests/Drupal/FunctionalTests/Installer/DistributionProfileTest.php
DistributionProfileTranslationQueryTest.php in core/tests/Drupal/FunctionalTests/Installer/DistributionProfileTranslationQueryTest.php
DistributionProfileTranslationTest.php in core/tests/Drupal/FunctionalTests/Installer/DistributionProfileTranslationTest.php
drupal-10.access-help-pages.php in core/modules/help/tests/fixtures/update/drupal-10.access-help-pages.php
Contains database additions for testing the help module permission.
DrupalFlushAllCachesInInstallerTest.php in core/tests/Drupal/FunctionalTests/Installer/DrupalFlushAllCachesInInstallerTest.php
editor-3412361.php in core/modules/editor/tests/fixtures/update/editor-3412361.php
Test fixture.
EntityTypeWithoutViewsDataTest.php in core/modules/datetime_range/tests/src/Kernel/Views/EntityTypeWithoutViewsDataTest.php
FileStorage.php in core/lib/Drupal/Core/Config/FileStorage.php
FileStorageTest.php in core/tests/Drupal/KernelTests/Core/Config/Storage/FileStorageTest.php
fix-revision-id-update.php in core/modules/views/tests/fixtures/update/fix-revision-id-update.php
Test fixture.
FunctionalTestSetupTrait.php in core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php
GenerateThemeTest.php in core/tests/Drupal/Tests/Core/Command/GenerateThemeTest.php
GenerateThemeTest.php in core/tests/Drupal/BuildTests/Command/GenerateThemeTest.php
help-topics-3087499.php in core/modules/help/tests/fixtures/update/help-topics-3087499.php
Contains database additions for testing the upgrade path for help topics.
HelpTopicDiscovery.php in core/modules/help/src/HelpTopicDiscovery.php
HelpTopicTwigLoader.php in core/modules/help/src/HelpTopicTwigLoader.php
InfoParserDynamic.php in core/lib/Drupal/Core/Extension/InfoParserDynamic.php
InfoWriterTrait.php in core/tests/Drupal/TestTools/Extension/InfoWriterTrait.php
InstallerNonEnglishProfileWithoutLocaleModuleTest.php in core/tests/Drupal/FunctionalTests/Installer/InstallerNonEnglishProfileWithoutLocaleModuleTest.php
InstallerRouterTest.php in core/tests/Drupal/FunctionalTests/Installer/InstallerRouterTest.php
LibraryDiscoveryParser.php in core/lib/Drupal/Core/Asset/LibraryDiscoveryParser.php
MaintenanceThemeUpdateRegistryTest.php in core/modules/system/tests/src/Functional/Theme/MaintenanceThemeUpdateRegistryTest.php
ModuleInstaller.php in core/lib/Drupal/Core/Extension/ModuleInstaller.php
remove_default_argument_skip_url.php in core/modules/views/tests/fixtures/update/remove_default_argument_skip_url.php
Test fixture.
SingleVisibleProfileTest.php in core/tests/Drupal/FunctionalTests/Installer/SingleVisibleProfileTest.php
SuperUserAccessInstallTest.php in core/tests/Drupal/FunctionalTests/Installer/SuperUserAccessInstallTest.php
TwigEnvironment.php in core/lib/Drupal/Core/Template/TwigEnvironment.php
YamlDiscovery.php in core/lib/Drupal/Core/Discovery/YamlDiscovery.php
YamlFileLoader.php in core/lib/Drupal/Core/DependencyInjection/YamlFileLoader.php

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