UserFactory vs MockUserFactory - log in as

UserBuilderInterface.php

<?php	

    interface UserBuilderInterface {
            public function getUser();
    }
     
    // default implementation
    class UserFactory implements UserBuilderInterface {
           
            public function __construct(AuthenticatorServiceInterface $authenticator, UserRepository $userRepo)
            {
                    $this->authenticator = $authenticator
                    $this->repo = $userRepo;
            }
           
            public function getUser()
            {
                    $user =  $this->repo->findByIdentifier($authenticator->getIdentifier());
                    if (empty($user)) {
                            throw new UserNotExistsException();
                    }
                    return $user;
            }
    }
     
    // mocked user implementation
    class MockUserFactory extends UserFactory {
     
            public function getUser()
            {
                    if ($authenticator->hasMockIdentifier()) {
                            $user = $this->repo->findByIdentifier($authenticator->getMockIdentifier());
     
                            if (empty($user)) {
                                    throw new UserNotExistsException();
                            }
                            return $user;
                    }
     
                    return parent::getUser();
            }
    }