campisano/cpp_tdd_2048_game

2048 Game

Game description in https://en.wikipedia.org/wiki/2048_(video_game)#Gameplay

Test Specs

Business rules

1. There is a board:

   • board is a set of positions organized in rows and columns (e.g. 16 positions in a 4 rows and 4 columns);
   • a board can not have less than 2 positins, less than 2 rows and less than 2 columns;
   • player can make a slide in one direction {left,right,up,down}:
     • a slide is applied to all the numbers in the board, starting from the nearest to the destination of the slide;
     • a sliding number will stop when encounter a board edge or a number that cannot be merged;
     • if a sliding number encounters a number that can be merged, it will be merged in the number and the sliding number will be removed from the board;
     • if a sliding number encounter a number that was already merged, it must stop;
   • a number can be placed randomly in a board empty position.

2. There are numbers:

   • a number has a value;
   • a value must be greater than or equal to 2;
   • a value must be power of two;
   • a number A can merge in another number B with the same value:
     • the B number will became merged and will have the double of its original value;
     • the A number will be removed from its original place.

3. There are positions:

   • a position can have a number placed on itself;
   • a position can have adiacent positions {left,right,up,down}.

4. There is a player:

   • a player is queried for a valid direction to slide.

5. There is a game:

   • at every turn, a random number (with value of 2 or 4) is placed in a random empty spot of the board;
   • at every turn, a valid slide direction is requested to the player;
   • game ends when player win (when obtain a 2048 number) or lose (when can not slide due to end of spaces and mergeable slides in the board).

6. There is an observer:

   • an observer is notified about game events (start, number placed, player slided, end).

Use cases

1. A player starts a new game:

   • the player defines the end score and the board size;
   • the game validates the board size;
   • the game notifies the start with winning score and board size;
   • the game places a number;
   • the game notifies the number value and position.

2. The playar make a slide: