@Override
  public TableDescriptors getTableDescriptors() {
    return new TableDescriptors() {
      @Override
      public TableDescriptor remove(TableName tablename) throws IOException {
        // noop
        return null;
      }

      @Override
      public Map<String, TableDescriptor> getAll() throws IOException {
        // noop
        return null;
      }

      @Override
      public TableDescriptor get(TableName tablename) throws IOException {
        TableDescriptorBuilder builder = TableDescriptorBuilder.newBuilder(tablename);
        builder.setColumnFamily(ColumnFamilyDescriptorBuilder.of(DEFAULT_COLUMN_FAMILY_NAME));
        return builder.build();
      }

      @Override
      public Map<String, TableDescriptor> getByNamespace(String name) throws IOException {
        return null;
      }

      @Override
      public void update(TableDescriptor htd, boolean cacheOnly) throws IOException {
        // noop
      }
    };
  }
Call this restart method only after running MockMasterServices#start() The RSs can be
differentiated by the port number, see ServerName in MockMasterServices#start() method above.
Restart of region server will have new startcode in server name
@param serverName Server name to be restarted
hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/MockMasterServices.java