DatasetQueryFixtures
The fixtures and hooks of the dataset contract (DatasetQueryBackendSpec, the class a backend's test extends): the backend's hooks (createDatasetBindings, createTable, semanticDivergences), the Target a test queries, the orders every test reads, and the dataset a table compiles to (target).
The contract's cases come in families, one class each: DatasetRecordCases, DatasetAggregationCases and DatasetDateBucketCases, then DatasetQueryBackendSpec with 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 DatasetQueryBackendSpec, never a member of the family it extends, so any order would run the same cases.