sync state-of-tic-tac-toe (#301)

Author: keiravillekode

exercises/practice/state-of-tic-tac-toe/.meta/example.v

@@ -46,24 +46,27 @@ fn gamestate(board []string) !State {
 		}
 	}
 
-	if count_o > count_x {
-		return error('Wrong turn order: O started')
-	}
-
-	if count_x > count_o + 1 {
-		return error('Wrong turn order: X went twice')
-	}
-
 	mut win_x := is_win(bitset_x)
 	mut win_o := is_win(bitset_o)
 
-	if win_x || win_o {
-		if win_x && win_o {
-			return error('Impossible board: game should have ended after the game was won')
+	return match true {
+		count_o > count_x {
+			error('Wrong turn order: O started')
+		}
+		count_x > count_o + 1 {
+			error('Wrong turn order: X went twice')
+		}
+		(win_x && count_o == count_x) || (win_o && count_x == count_o + 1) || (win_x && win_o) {
+			error('Impossible board: game should have ended after the game was won')
+		}
+		win_x || win_o {
+			.win
+		}
+		count_x + count_o == 9 {
+			.draw
+		}
+		else {
+			.ongoing
 		}
-
-		return .win
 	}
-
-	return if count_x + count_o == 9 { .draw } else { .ongoing }
 }

exercises/practice/state-of-tic-tac-toe/.meta/tests.toml

@@ -92,3 +92,9 @@ reimplements = "b1dc8b13-46c4-47db-a96d-aa90eedc4e8d"
 
 [4801cda2-f5b7-4c36-8317-3cdd167ac22c]
 description = "Invalid boards -> Invalid board: players kept playing after a win"
+
+[5a84757a-fc86-4328-aec9-a5759e6ed35d]
+description = "Invalid boards -> Invalid board: O kept playing after X wins"
+
+[cf25543d-583a-4656-b9ab-f82dc00a4a02]
+description = "Invalid boards -> Invalid board: X kept playing after O wins"

exercises/practice/state-of-tic-tac-toe/run_test.v

@@ -258,3 +258,29 @@ fn test_invalid_boards__invalid_board__players_kept_playing_after_a_win() {
 		assert err.msg() == 'Impossible board: game should have ended after the game was won'
 	}
 }
+
+fn test_invalid_boards__invalid_board__o_kept_playing_after_x_wins() {
+	board := [
+		'OO ',
+		'XXX',
+		' O ',
+	]
+	if res := gamestate(board) {
+		assert false, 'Invalid board: O kept playing after X wins should return an error'
+	} else {
+		assert err.msg() == 'Impossible board: game should have ended after the game was won'
+	}
+}
+
+fn test_invalid_boards__invalid_board__x_kept_playing_after_o_wins() {
+	board := [
+		'XX ',
+		'OOO',
+		' XX',
+	]
+	if res := gamestate(board) {
+		assert false, 'Invalid board: X kept playing after O wins should return an error'
+	} else {
+		assert err.msg() == 'Impossible board: game should have ended after the game was won'
+	}
+}