Chess - Low level system design

Video Explanation

Implement checkmate feature.
Write more unit tests.
Support special move of pawn where it can go diagonal when it kills.
At many places, we are evaluating conditions like:
- OR Operation: We are allowed to do something if any condition out of given conditions fulfill.
- And Operation: We are allowed to do something if all conditions fulfill.
  Try to improve the design for this.
Add history of moves for each player.
Add support for casteling move.
Can we remove putting currentCell in Piece? How about introducing something like position?
- A piece will have a position and you can always get the cell back from board using this position.