If you run FastBatchingCellReaderTest with aggregates and native disabled, it succeeds. But if you run it after MultipleColsInAggTest, two of the FastBatchingCellReaderTest tests fail.
The problem is that AggregateTableManager.initialize() can only be called once, and only runs if mondrian.rolap.aggregates.Read=true.
Aggregates are read by setting the mondrian.rolap.aggregates.Read property to false then true, and using triggers on the property (MondrianProperty.ReadAggregates). It's a real mess. I'd like to make AggTableManager not-a-singleton – maybe it should belong to a MondrianServer instance – and if you really want to re-load, maybe you could create a new MondrianServer.
Until this issue is fixed, we'll if 'if (Bug.BugMondrian1001Fixed) ...' to tag tests that have been disabled.