anchor.diff:  -spec init_per_testcase(atom(), serpents_test_utils:config()) ->
     serpents_test_utils:config().
   init_per_testcase(JoinGameTest, Config)
  -  when JoinGameTest == join_game_ok; JoinGameTest == join_game_wrong ->
  +  when JoinGameTest == join_game_ok
  +     ; JoinGameTest == join_game_wrong ->
     Game = serpents_core:create_game(#{cols => 10, rows => 10}),
     Player1 = serpents_core:register_player(<<"1">>),
     Player2 = serpents_core:register_player(<<"2">>),
  
positive.code: -spec end_per_testcase(atom(), serpents_test_utils:config()) ->
    serpents_test_utils:config().
  end_per_testcase(JoinGameTest, Config)
    when JoinGameTest == join_game_ok; JoinGameTest == join_game_wrong ->
    lists:filter(
      fun ({K, _}) -> not lists:member(K, [game, player1, player2, player3]) end,
      Config);
  
negative.code:         , game_creation_bad_cols/1
          , join_game_ok/1
          , join_game_wrong/1
          , too_many_joins/1
          % , start_game_wrong/1
          % , start_game_ok/1
          ]).
  
  -spec all() -> [atom()].
  