Configuration for in-memory persistence for integration test of cluster

Could you suggest an example of configuration for in-memory configuration for minimal cluster of one node and 2 shards?
its needed for integration style test as a part of build. Test has to be local to build node, no dependencies on distributed services.
What are values for “akka.cluster.sharding.journal-plugin-id” and “akka.cluster.sharding.snapshot-plugin-id” for in-memory ?
If in-memory persistence is not possible, then which type do you suggest? Do you have an example of how to configure it?