Code review comment for lp:~renatofilho/address-book-app/dynamic-backend

57 + // use galare as default QtContacts Manager
58 + if (qEnvironmentVariableIsSet("QTCONTACTS_MANAGER_OVERRIDE")) {
59 + defaultManager = qgetenv("QTCONTACTS_MANAGER_OVERRIDE");
60 + }

Wouldn't it be a good idea to check if the value set from command line actually exists in the list of available managers?