Persistence integration tests provide assurances that the schema assumed by the code matches that available in the data store.

In the case that an ORM is in use, these tests also give confidence that any mappings configured in the tool are compatible with the result sets coming back.

Modern ORMs are very sophisticated in terms of caching and only flushing when necessary. It is important to structure tests such that transactions close in between preconditions, actions and assertions to be sure data makes a full round trip.

Since most data stores exist across a network partition, they are also subject to timeouts and network failures. Integration tests should attempt to verify that the integration modules handle these failures gracefully.