6 files declare their use of YamlDefinitionsLoader in Hook Event Dispatcher 8

EntityEventTest.php in tests/src/Unit/Preprocess/EntityEventTest.php

EntityEventVariablesTest.php in tests/src/Unit/Preprocess/EntityEventVariablesTest.php

FactoryMapperTest.php in tests/src/Unit/Preprocess/FactoryMapperTest.php

OtherEventTest.php in tests/src/Unit/Preprocess/OtherEventTest.php

OtherEventVariablesTest.php in tests/src/Unit/Preprocess/OtherEventVariablesTest.php

PreprocessEventPassTest.php in tests/src/Unit/Preprocess/PreprocessEventPassTest.php