    @Test
    public void testReadSnapshot() throws Exception {

        System.out.println("readSnapshot");

        IdManager idManager = new IdManager();
        IdReader reader = new IdReader(new DataInputStream(new ByteArrayInputStream(emptyDiffEmpty)), idManager);
        Snapshot oldSnapshot = idManager.getInitialSnapshot();

        ImmutableArrayList<CellBackup> expCellBackups = new ImmutableArrayList<CellBackup>(CellBackup.NULL_ARRAY);
        Snapshot result = Snapshot.readSnapshot(reader, oldSnapshot);
        assertEquals(expCellBackups, result.cellBackups);
    }