@Test
 public void testTo() throws Exception {
   Iterable<StorageKey> partitions =
       new FileSystemPartitionIterator(
           fileSystem,
           testDirectory,
           strategy,
           schema,
           emptyConstraints.to("timestamp", oct_25_2012).toKeyPredicate());
   assertIterableEquals(keys.subList(0, 6), partitions);
 }