SnapshotQueryFixtures
The fixtures and hooks of the snapshot contract (QueryBackendSpec, the class a backend's test extends): the backend's hooks (store, binding, semanticDivergences), the test's own aggregate type, the Fixture a test queries, and the snapshots it stores (snapshot, orders).
The contract's cases come in families, one class each: SnapshotFilterCases, SnapshotRecordCases, SnapshotKeysetCases, SnapshotAggregationCases and SnapshotDateBucketCases, then QueryBackendSpec with the timeouts and the gateway. They form one chain, in that order, each extending the one before, because a class has one superclass and JUnit runs the cases a test class inherits. The order means nothing: every family reads only this class's fixtures, hooks and constants, and the suite's public constants on QueryBackendSpec, never a member of the family it extends, so any order would run the same cases.