public virtual void TestDatanodeDetect()
        {
            AtomicReference <DatanodeProtocolProtos.BlockReportRequestProto> request = new AtomicReference
                                                                                       <DatanodeProtocolProtos.BlockReportRequestProto>();
            // just capture the outgoing PB
            DatanodeProtocolPB mockProxy = Org.Mockito.Mockito.Mock <DatanodeProtocolPB>();

            Org.Mockito.Mockito.DoAnswer(new _Answer_205(request)).When(mockProxy).BlockReport
                (Matchers.Any <RpcController>(), Matchers.Any <DatanodeProtocolProtos.BlockReportRequestProto
                                                               >());
            DatanodeProtocolClientSideTranslatorPB nn = new DatanodeProtocolClientSideTranslatorPB
                                                            (mockProxy);
            DatanodeRegistration reg    = DFSTestUtil.GetLocalDatanodeRegistration();
            NamespaceInfo        nsInfo = new NamespaceInfo(1, "cluster", "bp", 1);

            reg.SetNamespaceInfo(nsInfo);
            Replica          r       = new FinalizedReplica(new Block(1, 2, 3), null, null);
            BlockListAsLongs bbl     = BlockListAsLongs.Encode(Sharpen.Collections.Singleton(r));
            DatanodeStorage  storage = new DatanodeStorage("s1");

            StorageBlockReport[] sbr = new StorageBlockReport[] { new StorageBlockReport(storage
                                                                                         , bbl) };
            // check DN sends new-style BR
            request.Set(null);
            nsInfo.SetCapabilities(NamespaceInfo.Capability.StorageBlockReportBuffers.GetMask
                                       ());
            nn.BlockReport(reg, "pool", sbr, new BlockReportContext(1, 0, Runtime.NanoTime())
                           );
            DatanodeProtocolProtos.BlockReportRequestProto proto = request.Get();
            NUnit.Framework.Assert.IsNotNull(proto);
            NUnit.Framework.Assert.IsTrue(proto.GetReports(0).GetBlocksList().IsEmpty());
            NUnit.Framework.Assert.IsFalse(proto.GetReports(0).GetBlocksBuffersList().IsEmpty
                                               ());
            // back up to prior version and check DN sends old-style BR
            request.Set(null);
            nsInfo.SetCapabilities(NamespaceInfo.Capability.Unknown.GetMask());
            nn.BlockReport(reg, "pool", sbr, new BlockReportContext(1, 0, Runtime.NanoTime())
                           );
            proto = request.Get();
            NUnit.Framework.Assert.IsNotNull(proto);
            NUnit.Framework.Assert.IsFalse(proto.GetReports(0).GetBlocksList().IsEmpty());
            NUnit.Framework.Assert.IsTrue(proto.GetReports(0).GetBlocksBuffersList().IsEmpty(
                                              ));
        }