6 files declare their use of SelfDescribing

Constraint.php in vendor/phpunit/phpunit/src/Framework/Constraint/Constraint.php
Invocation.php in vendor/phpunit/phpunit/src/Framework/MockObject/Runtime/Invocation.php
InvocationOrder.php in vendor/phpunit/phpunit/src/Framework/MockObject/Runtime/Rule/InvocationOrder.php
NameFilterIterator.php in vendor/phpunit/phpunit/src/Runner/Filter/NameFilterIterator.php
PhptTestCase.php in vendor/phpunit/phpunit/src/Runner/PhptTestCase.php
ThrowableToStringMapper.php in vendor/phpunit/phpunit/src/Util/ThrowableToStringMapper.php