Add the new test file by HDFS-4520.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-2802@1449863 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotListing.java

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+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs.server.namenode.snapshot;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+import java.io.IOException;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hdfs.DistributedFileSystem;
+import org.apache.hadoop.hdfs.MiniDFSCluster;
+import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
+import org.apache.hadoop.test.GenericTestUtils;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+public class TestSnapshotListing {
+
+  static final long seed = 0;
+  static final short REPLICATION = 3;
+  static final long BLOCKSIZE = 1024;
+
+  private final Path dir = new Path("/test.snapshot/dir");
+  
+  Configuration conf;
+  MiniDFSCluster cluster;
+  FSNamesystem fsn;
+  DistributedFileSystem hdfs;
+  
+  @Before
+  public void setUp() throws Exception {
+    conf = new Configuration();
+    cluster = new MiniDFSCluster.Builder(conf).numDataNodes(REPLICATION)
+        .build();
+    cluster.waitActive();
+    fsn = cluster.getNamesystem();
+    hdfs = cluster.getFileSystem();
+    hdfs.mkdirs(dir);
+  }
+
+  @After
+  public void tearDown() throws Exception {
+    if (cluster != null) {
+      cluster.shutdown();
+    }
+  }
+  
+  /**
+   * Test listing snapshots under a snapshottable directory
+   */
+  @Test
+  public void testListSnapshots() throws Exception {
+    final Path snapshotsPath = new Path(dir, ".snapshot");
+    FileStatus[] stats = null;
+    
+    // special case: snapshots of root
+    stats = hdfs.listStatus(new Path("/.snapshot"));
+    // should be 0 since root's snapshot quota is 0
+    assertEquals(0, stats.length);
+    
+    // list before set dir as snapshottable
+    try {
+      stats = hdfs.listStatus(snapshotsPath);
+      fail("expect SnapshotException");
+    } catch (IOException e) {
+      GenericTestUtils.assertExceptionContains(
+          "Directory is not a snapshottable directory: " + dir.toString(), e);
+    }
+    
+    // list before creating snapshots
+    hdfs.allowSnapshot(dir.toString());
+    stats = hdfs.listStatus(snapshotsPath);
+    assertEquals(0, stats.length);
+    
+    // list while creating snapshots
+    final int snapshotNum = 5;
+    for (int sNum = 0; sNum < snapshotNum; sNum++) {
+      hdfs.createSnapshot(dir, "s_" + sNum);
+      stats = hdfs.listStatus(snapshotsPath);
+      assertEquals(sNum + 1, stats.length);
+      for (int i = 0; i <= sNum; i++) {
+        assertEquals("s_" + i, stats[i].getPath().getName());
+      }
+    }
+    
+    // list while deleting snapshots
+    for (int sNum = snapshotNum - 1; sNum > 0; sNum--) {
+      hdfs.deleteSnapshot(dir, "s_" + sNum);
+      stats = hdfs.listStatus(snapshotsPath);
+      assertEquals(sNum, stats.length);
+      for (int i = 0; i < sNum; i++) {
+        assertEquals("s_" + i, stats[i].getPath().getName());
+      }
+    }
+    
+    // remove the last snapshot
+    hdfs.deleteSnapshot(dir, "s_0");
+    stats = hdfs.listStatus(snapshotsPath);
+    assertEquals(0, stats.length);
+  }
+}