9 files declare their use of JsonapiKernelTestBase in Drupal 8

EntityResourceTest.php in core/modules/jsonapi/tests/src/Kernel/Controller/EntityResourceTest.php

FieldResolverTest.php in core/modules/jsonapi/tests/src/Kernel/Context/FieldResolverTest.php

FilterTest.php in core/modules/jsonapi/tests/src/Kernel/Query/FilterTest.php

JsonApiDocumentTopLevelNormalizerTest.php in core/modules/jsonapi/tests/src/Kernel/Normalizer/JsonApiDocumentTopLevelNormalizerTest.php

RelatedResourceTypesTest.php in core/modules/jsonapi/tests/src/Kernel/ResourceType/RelatedResourceTypesTest.php

RelationshipNormalizerTest.php in core/modules/jsonapi/tests/src/Kernel/Normalizer/RelationshipNormalizerTest.php

ResourceTypeRepositoryTest.php in core/modules/jsonapi/tests/src/Kernel/ResourceType/ResourceTypeRepositoryTest.php

SerializerTest.php in core/modules/jsonapi/tests/src/Kernel/Serializer/SerializerTest.php

VersionNegotiatorTest.php in core/modules/jsonapi/tests/src/Kernel/Revisions/VersionNegotiatorTest.php