anchor.diff:  send_invalid_avp_length(Config) ->
       Req = ['STR', {'Termination-Cause', ?LOGOUT}],
   
  -    ['STA', {'Session-Id', _},
  -            {'Result-Code', ?INVALID_AVP_LENGTH},
  -            {'Origin-Host', _},
  -            {'Origin-Realm', _},
  -            {'User-Name', _},
  -            {'Class', _},
  -            {'Error-Message', _},
  -            {'Error-Reporting-Host', _}
  -          | Avps]
  +    #{':name' := 'STA',
  +      'Session-Id' := _,
  +      'Result-Code' := ?INVALID_AVP_LENGTH,
  +      'Origin-Host' := _,
  +      'Origin-Realm' := _,
  +      'User-Name' := _,
  +      'Class' := _,
  +      'Error-Message' := _,
  +      'Error-Reporting-Host' := _,
  +      'Failed-AVP' := Avps}
           = call(Config, Req),
       [[_]] = failed_avps(Avps, Config).
   
  
positive.code: send_arbitrary(Config) ->
      Req = ['ASR', {'AVP', [#diameter_avp{name = 'Product-Name',
                                           value = "XXX"}]}],
      ['ASA', {'Session-Id', _}, {'Result-Code', ?SUCCESS} | Avps]
          = call(Config, Req),
      {'AVP', [#diameter_avp{name = 'Product-Name',
                             value = V}]}
          = lists:last(Avps),
      "XXX" = string(V, Config).
  
  %% Send an unknown AVP (to some client) and check that it comes back.
  
negative.code:     Req = ['ASR', {'AVP', [#diameter_avp{code = 999,
                                           is_mandatory = M,
                                           data = <<17>>}]}],
      #{':name' := 'ASA',
        'Session-Id' := _,
        'Result-Code' := RC,
        'Failed-AVP' := Avps}
          = call(Config, Req),
      [[#diameter_avp{code = 999,
                      is_mandatory = M,
  