### Question:
FSTableDescriptors implements TableDescriptors { static int getTableInfoSequenceid(final Path p) { if (p == null) return 0; Matcher m = SUFFIX.matcher(p.getName()); if (!m.matches()) throw new IllegalArgumentException(p.toString()); String suffix = m.group(2); if (suffix == null || suffix.length() <= 0) return 0; return Integer.parseInt(m.group(2)); } FSTableDescriptors(final FileSystem fs, final Path rootdir);  FSTableDescriptors(final FileSystem fs, final Path rootdir,
      final boolean fsreadOnly); @Override HTableDescriptor get(final byte [] tablename); @Override HTableDescriptor get(final String tablename); @Override Map<String, HTableDescriptor> getAll(); @Override void add(HTableDescriptor htd); @Override HTableDescriptor remove(final String tablename); static boolean isTableInfoExists(FileSystem fs, Path rootdir,
      String tableName); static FileStatus getTableInfoPath(final FileSystem fs,
      final Path tabledir); static HTableDescriptor getTableDescriptor(FileSystem fs,
      Path hbaseRootDir, byte[] tableName); static HTableDescriptor getTableDescriptor(FileSystem fs, Path tableDir); static void deleteTableDescriptorIfExists(String tableName,
      Configuration conf); static boolean createTableDescriptor(final HTableDescriptor htableDescriptor,
      Configuration conf); static boolean createTableDescriptor(FileSystem fs, Path rootdir,
      HTableDescriptor htableDescriptor); static boolean createTableDescriptor(FileSystem fs, Path rootdir,
      HTableDescriptor htableDescriptor, boolean forceCreation); static boolean createTableDescriptorForTableDirectory(FileSystem fs, Path tabledir,
      HTableDescriptor htableDescriptor, boolean forceCreation); static final String TABLEINFO_NAME; }### Answer:
@Test (expected=IllegalArgumentException.class) public void testRegexAgainstOldStyleTableInfo() { Path p = new Path("/tmp", FSTableDescriptors.TABLEINFO_NAME); int i = FSTableDescriptors.getTableInfoSequenceid(p); assertEquals(0, i); p = new Path("/tmp", "abc"); FSTableDescriptors.getTableInfoSequenceid(p); }