anchor.diff:      Board = new_game(4, 4, 4, [0,2,3,8]),
       {Events, #board{n_hidden = NHidden}} = step({2,2}, Board),
       ?assertEqual(7, NHidden),
  -    ?assertMatch([{uncover, 15, {empty, 0}},
  -                  {uncover, 13, {empty, 1}},
  -                  {uncover, 14, {empty, 0}},
  -                  {uncover, 11, {empty, 0}},
  -                  {uncover,  9, {empty, 1}},
  -                  {uncover,  7, {empty, 2}},
  -                  {uncover,  6, {empty, 2}},
  -                  {uncover,  5, {empty, 3}},
  -                  {uncover, 10, {empty, 0}}], Events).
  +    ?assertMatch([{uncovered, 15, {empty, 0}},
  +                  {uncovered, 13, {empty, 1}},
  +                  {uncovered, 14, {empty, 0}},
  +                  {uncovered, 11, {empty, 0}},
  +                  {uncovered,  9, {empty, 1}},
  +                  {uncovered,  7, {empty, 2}},
  +                  {uncovered,  6, {empty, 2}},
  +                  {uncovered,  5, {empty, 3}},
  +                  {uncovered, 10, {empty, 0}}], Events).
   
   step_on_hole2_test() ->
       %%  *0, 1,*2,*3
  
positive.code:     ?assertEqual(2, nbr(mines, F5, Fields)),
      ?assertEqual(5, nbr(mines, F6, Fields)).
  
  step_on_empty_test() ->
      Board = new_game(3, 4, 5, [2,3,5,7,9]),
      {Events, #board{n_hidden = NHidden, fields=NewFields}} = step({1,2}, Board),
      ?assertEqual(11, NHidden),
      ?assertMatch([{uncover, 6, {empty, 5}}], Events),
      ?assertMatch(#field{status=uncovered}, array:get(6, NewFields)).
  
  step_on_mine_test() ->
  
negative.code:                             Type = if HasMine -> mine;
                                        true -> {empty, nbr(mines, F, Fields)}
                                     end,
                              [{uncovered, I, Type} | UEs];
                         (_I, #field{}, UEs) -> UEs
                      end, Events, Fields),
  
  