// ok - as expected
        public virtual void CheckInvalidBlock(ExtendedBlock b)
        {
            SimulatedFSDataset fsdataset = GetSimulatedFSDataset();

            NUnit.Framework.Assert.IsFalse(fsdataset.IsValidBlock(b));
            try
            {
                fsdataset.GetLength(b);
                NUnit.Framework.Assert.IsTrue("Expected an IO exception", false);
            }
            catch (IOException)
            {
            }
            // ok - as expected
            try
            {
                fsdataset.GetBlockInputStream(b);
                NUnit.Framework.Assert.IsTrue("Expected an IO exception", false);
            }
            catch (IOException)
            {
            }
            // ok - as expected
            try
            {
                fsdataset.FinalizeBlock(b);
                NUnit.Framework.Assert.IsTrue("Expected an IO exception", false);
            }
            catch (IOException)
            {
            }
        }
        /// <exception cref="System.IO.IOException"/>
        internal virtual void CheckBlockDataAndSize(SimulatedFSDataset fsdataset, ExtendedBlock
                                                    b, long expectedLen)
        {
            InputStream input      = fsdataset.GetBlockInputStream(b);
            long        lengthRead = 0;
            int         data;

            while ((data = input.Read()) != -1)
            {
                NUnit.Framework.Assert.AreEqual(SimulatedFSDataset.DefaultDatabyte, data);
                lengthRead++;
            }
            NUnit.Framework.Assert.AreEqual(expectedLen, lengthRead);
        }