@Override
  public String toString() {
    long inKB = size / KB_COEFFICIENT;

    if (inKB == 0)
      return size + " Bytes";

    long inMB = size / MB_COEFFICIENT;
    if (inMB == 0) {
      return inKB + " KB";
    }

    long inGB = size / GB_COEFFICIENT;
    if(inGB == 0) {
      return inMB + " MB";
    }

    return inGB + " GB";
  }
@Test
  public void testToString() {
    {
      FileSize fs = new FileSize(8);
      assertEquals("8 Bytes", fs.toString());
    }
    {
      FileSize fs = new FileSize(8 * 1024 + 3);
      assertEquals("8 KB", fs.toString());
    }

    {
      FileSize fs = new FileSize(8 * 1024 * 1024 + 3 * 1024);
      assertEquals("8 MB", fs.toString());
    }

    {
      FileSize fs = new FileSize(8*1024*1024*1024L);
      assertEquals("8 GB", fs.toString());
    }
  }