The update modifies several test classes within the "chill-project" to change non-static class-level variables and methods to static ones. This change has been made to improve readability, performance, and to eliminate unnecessary instantiation of class objects in test scenarios. Also, flush and clear actions on the entity manager are moved to individual data providers.
For an unknown reason, in some circumstances, the use of the `===` comparator does not work when comparing Center instances and Scope instances. Then, we compare them based on the id.