anchor.diff:  %% Test Cases --------------------------------------------------------
   %%--------------------------------------------------------------------
   
  +%% openssl s_client cannot be configured to support both TLS 1.3 and TLS 1.2.
  +%% In its ClientHello the supported_versions extension contains only one element
  +%% [{3,4}] that the server does not accept if it is configured to not support
  +%% TLS 1.3.
   tls13_client_tls12_server() ->
       [{doc,"Test that a TLS 1.3 client can connect to a TLS 1.2 server."}].
   
  
positive.code:                 
              
  %%     ssl_test_lib:basic_test(ClientOpts, ServerOpts, Config).
     
  tls12_client_tls13_server() ->
      [{doc,"Test that a TLS 1.2 client can connect to a TLS 1.3 server."}].
  
  tls12_client_tls13_server(Config) when is_list(Config) ->    
      ClientOpts = [{versions,
                     ['tlsv1.1', 'tlsv1.2']} | ssl_test_lib:ssl_options(client_cert_opts, Config)],
      ServerOpts =  [{versions,
  
negative.code:      {group, ecdsa}].
  
  tests() ->
      [%%tls13_client_tls12_server, %% Not testable with current openssl s_client
       %%tls13_client_with_ext_tls12_server,
       tls12_client_tls13_server].
      
  