[ ] Be sure to check the list itself with an assertion, what you have works, but it would be more clear to also make sure the list size is > 0, for example
[ ] This testing feels a little clunky. Could you add the sheet and then retrieve that sheet directly from the database to make sure it's there, also check any relevant fields? Same with getSheet - make sure the various fields of the sheet have the expected values.
[ ] Does this pass? Is sheet and newSheet the same object, or should the individual values be checked?
[ ] This seems like a good candidate for an enumeration.
[ ] should this be it's own class or a utility? Feels out of place having the code right in the dao.