Added en passant to possible moves

chess.py

@@ -198,9 +198,9 @@ class Game:
 
         if piece == "pawn":
             r = []
-            dir = up
+            dir, back = up, down
             if color == "black":
-                dir = down
+                dir, back = down, up
             frwd = move(sq, dir)
             jump = move(frwd, dir)
 
@@ -209,7 +209,12 @@ class Game:
                 is_on_pawn_rank = pawn_ranks[color] == sq[1]
                 if is_on_pawn_rank and is_empty(jump):
                     r.append(jump)
-            return r + [sq for sq in targets if can_eat(sq)]
+            for t in targets:
+                a, b = move(t, dir), move(t, back)
+                en_passant = can_eat(b) and self.moves[-1] == (a,b)
+                if can_eat(t) or en_passant:
+                    r.append(t)
+            return r
         elif piece == "king":
             return [sq for sq in targets if not self.is_attacked(color, sq)]
         else:
@@ -265,7 +270,7 @@ def test():
     game = Game()
     assert len(squares) == 8**2
     assert sum(map(len, init_positions.values())) == 8*4
-    moves = [("a2", "a4"), ("b1", "c3"), ("c3", "b5"), ("b8", "c6")]
+    moves = [("a2", "a4"), ("b8", "c6"), ("a4", "a5"), ("b7", "b5"), ("a5", "b6")]
     for m in moves:
         game.move(*m)
         print (game)