code: /** 
   * Basic isInMemory Test.
   * @throws InvalidPathException
   * @throws FileAlreadyExistException
   * @throws IOException
   */
  @Test public void isInMemoryTest() throws InvalidPathException, FileAlreadyExistException, IOException {
    int fileId=TestUtils.createByteFile(mTfs,"/file1",WriteType.MUST_CACHE,USER_QUOTA_UNIT_BYTES);
    TachyonFile file=mTfs.getFile(fileId);
    Assert.assertTrue(file.isInMemory());
    fileId=TestUtils.createByteFile(mTfs,"/file2",WriteType.CACHE_THROUGH,USER_QUOTA_UNIT_BYTES);
    file=mTfs.getFile(fileId);
    Assert.assertTrue(file.isInMemory());
    fileId=TestUtils.createByteFile(mTfs,"/file3",WriteType.THROUGH,USER_QUOTA_UNIT_BYTES);
    file=mTfs.getFile(fileId);
    Assert.assertFalse(file.isInMemory());
    Assert.assertTrue(file.recache());
    Assert.assertTrue(file.isInMemory());
    fileId=TestUtils.createByteFile(mTfs,"/file4",WriteType.THROUGH,WORKER_CAPACITY_BYTES + 1);
    file=mTfs.getFile(fileId);
    Assert.assertFalse(file.isInMemory());
    Assert.assertFalse(file.recache());
    Assert.assertFalse(file.isInMemory());
    fileId=TestUtils.createByteFile(mTfs,"/file5",WriteType.THROUGH,WORKER_CAPACITY_BYTES);
    file=mTfs.getFile(fileId);
    Assert.assertFalse(file.isInMemory());
    Assert.assertTrue(file.recache());
    Assert.assertTrue(file.isInMemory());
  }
  