public virtual void TestClearQuota()
        {
            Path dir = new Path("/TestSnapshot");

            hdfs.Mkdirs(dir);
            hdfs.AllowSnapshot(dir);
            hdfs.SetQuota(dir, HdfsConstants.QuotaDontSet, HdfsConstants.QuotaDontSet);
            INodeDirectory dirNode = fsdir.GetINode4Write(dir.ToString()).AsDirectory();

            NUnit.Framework.Assert.IsTrue(dirNode.IsSnapshottable());
            NUnit.Framework.Assert.AreEqual(0, dirNode.GetDiffs().AsList().Count);
            hdfs.SetQuota(dir, HdfsConstants.QuotaDontSet - 1, HdfsConstants.QuotaDontSet - 1
                          );
            dirNode = fsdir.GetINode4Write(dir.ToString()).AsDirectory();
            NUnit.Framework.Assert.IsTrue(dirNode.IsSnapshottable());
            NUnit.Framework.Assert.AreEqual(0, dirNode.GetDiffs().AsList().Count);
            hdfs.SetQuota(dir, HdfsConstants.QuotaReset, HdfsConstants.QuotaReset);
            dirNode = fsdir.GetINode4Write(dir.ToString()).AsDirectory();
            NUnit.Framework.Assert.IsTrue(dirNode.IsSnapshottable());
            NUnit.Framework.Assert.AreEqual(0, dirNode.GetDiffs().AsList().Count);
            // allow snapshot on dir and create snapshot s1
            SnapshotTestHelper.CreateSnapshot(hdfs, dir, "s1");
            // clear quota of dir
            hdfs.SetQuota(dir, HdfsConstants.QuotaReset, HdfsConstants.QuotaReset);
            // dir should still be a snapshottable directory
            dirNode = fsdir.GetINode4Write(dir.ToString()).AsDirectory();
            NUnit.Framework.Assert.IsTrue(dirNode.IsSnapshottable());
            NUnit.Framework.Assert.AreEqual(1, dirNode.GetDiffs().AsList().Count);
            SnapshottableDirectoryStatus[] status = hdfs.GetSnapshottableDirListing();
            NUnit.Framework.Assert.AreEqual(1, status.Length);
            NUnit.Framework.Assert.AreEqual(dir, status[0].GetFullPath());
            Path subDir = new Path(dir, "sub");

            hdfs.Mkdirs(subDir);
            hdfs.CreateSnapshot(dir, "s2");
            Path file = new Path(subDir, "file");

            DFSTestUtil.CreateFile(hdfs, file, Blocksize, Replication, seed);
            hdfs.SetQuota(dir, HdfsConstants.QuotaReset, HdfsConstants.QuotaReset);
            INode subNode = fsdir.GetINode4Write(subDir.ToString());

            NUnit.Framework.Assert.IsTrue(subNode.AsDirectory().IsWithSnapshot());
            IList <DirectoryWithSnapshotFeature.DirectoryDiff> diffList = subNode.AsDirectory(
                ).GetDiffs().AsList();

            NUnit.Framework.Assert.AreEqual(1, diffList.Count);
            Org.Apache.Hadoop.Hdfs.Server.Namenode.Snapshot.Snapshot s2 = dirNode.GetSnapshot
                                                                              (DFSUtil.String2Bytes("s2"));
            NUnit.Framework.Assert.AreEqual(s2.GetId(), diffList[0].GetSnapshotId());
            IList <INode> createdList = diffList[0].GetChildrenDiff().GetList(Diff.ListType.Created
                                                                              );

            NUnit.Framework.Assert.AreEqual(1, createdList.Count);
            NUnit.Framework.Assert.AreSame(fsdir.GetINode4Write(file.ToString()), createdList
                                           [0]);
        }