I'm trying to run: vendor/bin/codecept build with a test suite which one of its modules now has methods with a fluid interface, that is, they have as return type ': self' and I get this error:

PHP Fatal error:  '\self' is an invalid class name in C:\...\tests\_build\support\_
generated\FunctionalTesterActions.php on line 4474

  Compile Error: '\self' is an invalid class name  

Check out the failed build here.