The test check that we can create and fetch items correctly. Commented
implemented for update and delete are provided but currently useless
since no implemented of update/delete are present in AccountancySystem.
Testing object creation without having object deletion is still useful
for tests purpose, since objects created in an accountancy tests would
involve the accountancy system and using an existing one could lead to
uniqueness errors, whereas creating new ones ensure the
AccountingAccount can be created regardless.
