anchor.diff:       {group, options_tls},
        {group, session},
        {group, 'dtlsv1.2'},
  -     {group, 'dtlsv1'}, 
  +     {group, 'dtlsv1'},
  +     {group, 'tlsv1.3'},
        {group, 'tlsv1.2'},
        {group, 'tlsv1.1'},
        {group, 'tlsv1'},
  
positive.code:                                        GroupName == options;
                                         GroupName == basic;
                                         GroupName == session;
                                         GroupName == error_handling_tests_tls
                                         ->
      ssl_test_lib:clean_tls_version(Config);                          
  init_per_group(GroupName, Config) ->
  
negative.code:     ssl_test_lib:close(Client1),
      ssl_test_lib:close(Client2).
      
  %%--------------------------------------------------------------------
  %% TLS 1.3
  %%--------------------------------------------------------------------
  
  tls13_enable_client_side() ->
      [{doc,"Test that a TLS 1.3 client can connect to a TLS 1.2 server."}].
  
  tls13_enable_client_side(Config) when is_list(Config) ->
      ClientOpts = ssl_test_lib:ssl_options(client_opts, Config),
      ServerOpts = ssl_test_lib:ssl_options(server_opts, Config),
  
      {ClientNode, ServerNode, Hostname} = ssl_test_lib:run_where(Config),
      Server = ssl_test_lib:start_server([{node, ServerNode}, {port, 0},
  					{from, self()},
  					{mfa, {?MODULE, protocol_info_result, []}},
  					{options, [{versions,
                                                      ['tlsv1.1', 'tlsv1.2']} | ServerOpts] }]),
      Port = ssl_test_lib:inet_port(Server),
  
      Client = ssl_test_lib:start_client([{node, ClientNode}, {port, Port},
  					{host, Hostname},
  					{from, self()},
  					{mfa, {?MODULE, protocol_info_result, []}},
  					{options,  [{versions,
                                                       ['tlsv1.2', 'tlsv1.3']} | ClientOpts]}]),
  
      ServerMsg = ClientMsg = {ok, 'tlsv1.2'},
      ssl_test_lib:check_result(Server, ServerMsg, Client, ClientMsg).
  
  tls13_enable_server_side() ->
      [{doc,"Test that a TLS 1.2 client can connect to a TLS 1.3 server."}].
  
  tls13_enable_server_side(Config) when is_list(Config) ->
      ClientOpts = ssl_test_lib:ssl_options(client_opts, Config),
      ServerOpts = ssl_test_lib:ssl_options(server_opts, Config),
  
      {ClientNode, ServerNode, Hostname} = ssl_test_lib:run_where(Config),
      Server = ssl_test_lib:start_server([{node, ServerNode}, {port, 0},
  					{from, self()},
  					{mfa, {?MODULE, protocol_info_result, []}},
  					{options, [{versions,
                                                      ['tlsv1.2', 'tlsv1.3']} | ServerOpts] }]),
      Port = ssl_test_lib:inet_port(Server),
  
      Client = ssl_test_lib:start_client([{node, ClientNode}, {port, Port},
  					{host, Hostname},
  					{from, self()},
  					{mfa, {?MODULE, protocol_info_result, []}},
  					{options,  [{versions,
                                                       ['tlsv1.2', 'tlsv1.1']} | ClientOpts]}]),
  
      ServerMsg = ClientMsg = {ok, 'tlsv1.2'},
      ssl_test_lib:check_result(Server, ServerMsg, Client, ClientMsg).
  
  
  %%--------------------------------------------------------------------
  %% Internal functions ------------------------------------------------
  