Improve the tests

The lines to add to the .gitlab-ci.yml file are the following.

.phpunit-base:
  before_script:
    - apt-get update
    - apt-get install -y --no-install-recommends $PHPIZE_DEPS
    - pecl install apcu && docker-php-ext-enable apcu

So far, I have not been able to make all the tests pass. The tests have been improved, but they cannot yet be enabled for GitLab CI.

Automatically closed - issue fixed for 2 weeks with no activity.