The PHPUnit Bridge documentation says “Once the component installed, it automatically registers a PHPUnit event listener which in turn registers a PHP error handler”.

This didn’t work for me, the error handler gets registered via the bootstrap.php file, but I had to register the PHPUnit event listener in the phpunit.xml file in order to get the @expectedDeprecation annotations working:

<listeners>
    <listener class="Symfony\Bridge\PhpUnit\SymfonyTestsListener" />
</listeners>