package org.apache.hadoop.dfs;import junit.framework.TestCase;import java.io.*;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.FileSystem;/** * This class tests the DFS class via the FileSystem interface in a single node * mini-cluster. * @author Owen O'Malley */public class TestLocalDFS extends TestCase {  private void writeFile(FileSystem fileSys, File name) throws IOException {    DataOutputStream stm = fileSys.create(name);    stm.writeBytes("oom");    stm.close();  }    private void readFile(FileSystem fileSys, File name) throws IOException {    DataInputStream stm = fileSys.open(name);    byte[] buffer = new byte[4];    int bytesRead = stm.read(buffer, 0 ,4);    assertEquals("oom", new String(buffer, 0 , bytesRead));    stm.close();  }    private void cleanupFile(FileSystem fileSys, File name) throws IOException {    assertTrue(fileSys.exists(name));    fileSys.delete(name);    assertTrue(!fileSys.exists(name));  }    /**   * Tests get/set working directory in DFS.   */  public void testWorkingDirectory() throws IOException {    Configuration conf = new Configuration();    MiniDFSCluster cluster = new MiniDFSCluster(65312, conf);    FileSystem fileSys = cluster.getFileSystem();    try {      File orig_path = fileSys.getWorkingDirectory();      assertTrue(orig_path.isAbsolute());      File file1 = new File("somewhat/random.txt");      writeFile(fileSys, file1);      assertTrue(fileSys.exists(new File(orig_path, file1.getPath())));      fileSys.delete(file1);      File subdir1 = new File("/somewhere").getAbsoluteFile();      fileSys.setWorkingDirectory(subdir1);      writeFile(fileSys, file1);      cleanupFile(fileSys, new File(subdir1, file1.getPath()));      File subdir2 = new File("else");      fileSys.setWorkingDirectory(subdir2);      writeFile(fileSys, file1);      readFile(fileSys, file1);      cleanupFile(fileSys, new File(new File(subdir1, subdir2.getPath()),                                     file1.getPath()));    } finally {      fileSys.close();      cluster.shutdown();    }  }}