Instead, should just use the DataNucleusObjectStore (configured with in-memory HSQLDB or H2 if required).
One important reason we should remove this objectstore is that the semantics/behaviour on the domain objects differs. For example, using DN bidirectional associations are automatically managed; this isn't the case with the in-memory objectstore.
Moreover, if an app becomes too big thus the integ tests become too slow, then the developer should modularize and decouple their app such that individual parts can be worked on independently. Having an in-memory objectstore dissuades the developer from "doing the right thing".