CLI/CLI/main.swift

@@ -3,43 +3,92 @@ import Foundation
 import Model
 import CustomTypes
 
-guard var board = Board(columns: 5, rows: 5) else {
-    print("Failed to create board.")
-    exit(EXIT_FAILURE)
+let ai = RandomPlayer(name: "Le robot a mythos", piece_type: .A)
+let cli = HumanPlayer(name: "Humain", piece_type: .B, callback: {
+    allowed_moves, board in
+    print("Available moves:")
+    for i in allowed_moves.indices {
+        print("\(i + 1)\t\(allowed_moves[i])")
+    }
+    print(">")
+    
+    guard let input = readLine(strippingNewline: true) else {
+        fatalError("Invalid input")
+    }
+    
+    guard let id = Int(input), id >= 1, id <= allowed_moves.count else {
+        fatalError("Invalid move id: \(input)")
+    }
+    
+    return allowed_moves[id - 1]
+})
+
+let players = [ cli, ai ]
+
+guard var rules = FourInARowRules(
+    columns: FourInARowRules.COLUMNS_DEFAULT,
+    rows: FourInARowRules.ROWS_DEFAULT,
+    players: players
+) else {
+    fatalError("Rules settings are invalid")
+}
+
+var board = rules.createBoard()
+
+guard rules.isValid(board: board) else {
+    fatalError("Board is invalid")
+}
+
+var state = rules.gameState(board: board, last_turn: nil)
+print(state)
+
+print("All moves:")
+for move in rules.validMoves(board: board) {
+    print(move)
+}
+
+print("Moves for \(PieceType.A):")
+for move in rules.validMoves(board: board, for_player: ai) {
+    print(move)
 }
 
-print(board.debugDescription)
 print(board)
 
-for i in 0...2 {
-    for _ in 0...i {
-        let dropAt = board.getInsertionCoordinates(from: .Top, offset: i)
-        let landAt = switch board.fallCoordinates(initialCoords: dropAt, direction: .Bottom) {
+while case .Playing(let turn) = state {
+    let action = turn.chooseMove(
+        allowed_moves: rules.validMoves(board: board, for_player: turn),
+        board: board
+    )
+    
+    let move = Move(player: turn, action: action)
+    guard rules.isValid(board: board, move: move) else {
+        fatalError("Move of \(turn) is invalid!")
+    }
+    
+    switch move.action {
+    case .InsertAt(let coords):
+        board[coords] = Piece(type: move.player.piece_type)
+    case .InsertOnSide(let side, let offset):
+        switch board.fallCoordinates(
+            initialCoords: board.getInsertionCoordinates(from: side, offset: offset),
+            direction: side.opposite
+        ) {
         case .Border(let at), .Piece(let at, _):
-            at
+            board[at] = Piece(type: move.player.piece_type)
         case .Occupied:
-            exit(EXIT_FAILURE)
+            fatalError("Not supported")
         }
-        
-        board[landAt] = Piece(owner: .A)
     }
+    
+    print(board)
+    
+    state = rules.gameState(board: board, last_turn: turn)
 }
 
-print(board)
-
-board[0, 2] = Piece(owner: .B)
-board[2, 4] = nil
-
-for c in 0..<board.rows {
-    switch board.fallCoordinates(initialCoords: board.getInsertionCoordinates(from: .Right, offset: c), direction: .Left) {
-    case .Border(let at):
-        board[at] = Piece(owner: .B)
-    case .Piece(let at, let touched):
-        (board[at], board[touched]) = (board[touched], Piece(owner: .B))
-    case .Occupied:
-        break
-    }
+if case .Win(let winner, _) = state {
+    print("\(winner.name) is the winner")
+} else {
+    print("Draw.")
 }
 
-print(board.debugDescription)
-print(board)
+exit(EXIT_SUCCESS)

CustomTypes/Sources/CustomTypes/Display.swift

@@ -1,6 +1,6 @@
 import Model
 
-extension Player: CustomStringConvertible {
+extension PieceType: CustomStringConvertible {
     public var description: String {
         switch self {
         case .A:
@@ -17,7 +17,7 @@ extension Board: CustomStringConvertible, CustomDebugStringConvertible {
         
         for row in 0..<self.rows {
             for col in 0..<self.columns {
-                str += self[col, row]?.owner.description ?? "⚪"
+                str += self[col, row]?.type.description ?? "⚪"
             }
             
             str += "\n"
@@ -27,7 +27,7 @@ extension Board: CustomStringConvertible, CustomDebugStringConvertible {
     }
     
     public var debugDescription: String {
-        return "Board[\(self.columns)x\(self.rows), \(self.countPieces { p in p.owner == .A }) A and \(self.countPieces { p in p.owner == .B }) B pieces]"
+        return "Board[\(self.columns)x\(self.rows), \(self.countPieces { p in p.type == .A }) A and \(self.countPieces { p in p.type == .B }) B pieces]"
     }
 }
 

CustomTypes/Tests/CustomTypesTests/DisplayTests.swift

@@ -9,10 +9,10 @@ final class CustomTypesTests: XCTestCase {
             return
         }
         
-        board[1, 1] = Piece(owner: .A)
-        board[2, 1] = Piece(owner: .A)
-        board[2, 2] = Piece(owner: .A)
-        board[1, 2] = Piece(owner: .B)
+        board[1, 1] = Piece(type: .A)
+        board[2, 1] = Piece(type: .A)
+        board[2, 2] = Piece(type: .A)
+        board[1, 2] = Piece(type: .B)
         
         let text: String = board.description
         

Model/Sources/Model/Board.swift

@@ -1,5 +1,5 @@
-public struct Board {
-	private var grid: [[Piece?]]
+public struct Board: Equatable {
+    private var grid: [[Piece?]]
     
     public var columns: Int { return grid.count }
     public var rows: Int { return grid.first!.count }
@@ -16,7 +16,7 @@ public struct Board {
         self.grid = grid
 	}
     
-    private func isInBounds(_ pos: Coords) -> Bool {
+    public func isInBounds(_ pos: Coords) -> Bool {
         pos.col >= 0 && pos.col < self.columns && pos.row >= 0 && pos.row < self.rows
     }
     
@@ -42,15 +42,21 @@ public struct Board {
         }
     }
     
+    public func forEach(_ consumer: (Piece?) -> Void) {
+        for column in grid {
+            for piece in column {
+                consumer(piece)
+            }
+        }
+    }
+    
     public func countPieces(filter: (Piece) -> Bool = { piece in true }) -> Int {
         var count = 0
         
-        for column in grid {
-            for piece in column {
-                if let piece = piece {
-                    if filter(piece) {
-                        count += 1
-                    }
+        self.forEach {
+            if let piece = $0 {
+                if filter(piece) {
+                    count += 1
                 }
             }
         }
@@ -117,4 +123,8 @@ public struct Board {
     }
     
     // TODO push
+    
+    public static func == (lhs: Board, rhs: Board) -> Bool {
+        lhs.grid == rhs.grid
+    }
 }

Model/Sources/Model/Coords.swift

@@ -11,4 +11,12 @@ public struct Coords: Equatable {
     public init(pair: (Int, Int)) {
         self.init(pair.0, pair.1)
     }
+    
+    /* static func +(lhs: Self, rhs: Self) -> Self {
+        Self(lhs.col + rhs.col, lhs.row + rhs.row)
+    }
+    
+    static func -(lhs: Self, rhs: Self) -> Self {
+        Self(lhs.col - rhs.col, lhs.row - rhs.row)
+    } */
 }

Model/Sources/Model/Direction.swift

@@ -1,7 +1,7 @@
-public enum Direction {
+public enum Direction: CaseIterable {
     case Top, Left, Bottom, Right
     
-    var opposite: Self {
+    public var opposite: Self {
         switch self {
         case .Top:
                 .Bottom

Model/Sources/Model/Piece.swift

@@ -1,8 +1,8 @@
-public struct Piece {
-    public let owner: Player
+public struct Piece: Equatable, Sendable {
+    public let type: PieceType
     
     // Required for public visibility
-    public init(owner: Player) {
-        self.owner = owner
+    public init(type: PieceType) {
+        self.type = type
     }
 }

Model/Sources/Model/PieceType.swift

@@ -0,0 +1,3 @@
+public enum PieceType: Equatable, CaseIterable, Sendable {
+    case A, B
+}

Model/Sources/Model/Player.swift

@@ -1,3 +0,0 @@
-public enum Player {
-    case A, B
-}

Model/Sources/Model/Players/AIPlayer.swift

@@ -0,0 +1,3 @@
+public class AIPlayer : Player {
+
+}

Model/Sources/Model/Players/HumanPlayer.swift

@@ -0,0 +1,15 @@
+public typealias MoveCallback = ([Move.Action], Board) -> Move.Action
+
+public class HumanPlayer : Player {
+    private let callback: MoveCallback
+
+    public init(name: String, piece_type: PieceType, callback: @escaping MoveCallback) {
+        self.callback = callback
+
+        super.init(name: name, piece_type: piece_type)
+    }
+
+    public override func chooseMove(allowed_moves moves: [Move.Action], board: Board) -> Move.Action {
+        callback(moves, board)
+    }
+}

Model/Sources/Model/Players/Player.swift

@@ -0,0 +1,18 @@
+public class Player : Equatable {
+    public let name: String
+    public let piece_type: PieceType
+
+    public init(name: String, piece_type: PieceType) {
+        self.name = name
+        self.piece_type = piece_type
+    }
+
+    public func chooseMove(allowed_moves moves: [Move.Action], board: Board) -> Move.Action {
+        fatalError("abstract method not implemented")
+    }
+    
+    public static func == (lhs: Player, rhs: Player) -> Bool {
+        // TODO: name equality or reference equality?
+        lhs === rhs
+    }
+}

Model/Sources/Model/Players/RandomPlayer.swift

@@ -0,0 +1,5 @@
+public class RandomPlayer : Player {
+    public override func chooseMove(allowed_moves moves: [Move.Action], board: Board) -> Move.Action {
+        moves[Int.random(in: moves.indices)]
+    }
+}

Model/Sources/Model/Rules/FourInARowRules.swift

@@ -0,0 +1,194 @@
+public struct FourInARowRules: Rules {
+    public static let COLUMNS_MIN: Int = 3
+    public static let COLUMNS_DEFAULT: Int = 7
+    public static let ROWS_MIN: Int = 3
+    public static let ROWS_DEFAULT: Int = 6
+    
+    private let players: [Player]
+
+    // // internal for unit testing purposes
+    // internal(set) public var state: GameState
+
+    // private(set) public var history: [Move] = []
+
+    private let columns: Int, rows: Int, minAligned: Int
+    
+    public init?(players: [Player]) {
+        self.init(columns: Self.COLUMNS_DEFAULT, rows: Self.ROWS_DEFAULT, players: players)
+    }
+
+    public init?(columns: Int, rows: Int, minAligned: Int = 4, players: [Player]) {
+        guard
+            columns >= Self.COLUMNS_MIN,
+            rows >= Self.ROWS_MIN,
+            minAligned > 1,
+            players.count >= 2
+        else {
+            return nil
+        }
+
+        self.players = players
+        self.columns = columns
+        self.rows = rows
+        self.minAligned = minAligned
+    }
+
+    public func createBoard() -> Board {
+        Board(columns: self.columns, rows: self.rows)!
+    }
+
+    public func isValid(board: Board, move: Move) -> Bool {
+        guard self.isValid(board: board) else { return false }
+
+        if case .InsertOnSide(.Top, let offset) = move.action, offset >= 0 && offset < self.columns {
+            return board.fallCoordinates(
+                initialCoords: Coords(offset, 0),
+                direction: .Bottom
+            ) != .Occupied
+        }
+
+        return false
+    }
+
+    public func isValid(board: Board) -> Bool {
+        for c in 0..<board.columns {
+            var had = false;
+
+            for r in 0..<board.rows {
+                switch board[c, r] != nil {
+                case false where had:
+                    return false
+
+                case let has:
+                    had = has
+                }
+            }
+        }
+
+        return true
+    }
+
+    public func validMoves(board: Board) -> [Move] {
+        return self.players.flatMap({
+            player in self.validMoves(board: board, for_player: player).map({
+                action in Move(player: player, action: action)
+            })
+        })
+    }
+
+    public func validMoves(board: Board, for_player player: Player) -> [Move.Action] {
+        var moves: [Move.Action] = [];
+
+        for c in 0..<board.columns {
+            switch board.fallCoordinates(initialCoords: Coords(c, 0), direction: .Bottom) {
+            case .Border, .Piece:
+                moves.append(.InsertOnSide(side: .Top, offset: c))
+
+            default:
+                break
+            }
+        }
+
+        return moves
+    }
+    
+    public func gameState(board: Board, last_turn: Player?) -> GameState {
+        Self.rowOfLengthWin(board: board, last_turn: last_turn, minimum_aligned: self.minAligned, players: self.players)
+    }
+    
+    internal static func rowOfLengthWin(board: Board, last_turn: Player?, minimum_aligned: Int, players: [Player]) -> GameState {
+        var occupied = 0
+        
+        for column in 0..<board.columns {
+            for row in 0..<board.rows {
+                let current = Coords(column, row)
+                guard let piece = board[current] else { continue }
+                
+                occupied += 1
+                
+                // For each "axis" (described as one direction)
+                for dir: (Int, Int) in [(1, 0), (0, 1), (1, 1), (-1, 1)] {
+                    let cells = Self.row(center: current, board: board, dir: dir)
+                    
+                    if cells.count >= minimum_aligned {
+                        let player = players.first(where: { $0.piece_type == piece.type })!
+                        return GameState.Win(winner: player, cells: cells)
+                    }
+                }
+            }
+        }
+        
+        if occupied == board.columns * board.rows {
+            return .Draw
+        } else if let last_turn = last_turn {
+            return .Playing(turn: players[(players.firstIndex(of: last_turn)! + 1) % players.count])
+        } else {
+            return .Playing(turn: players.first!)
+        }
+    }
+
+    /* public mutating func onMoveDone(move: Move, board: Board) -> Void {
+        // self.history.append(move)
+
+        switch move.action {
+        case .InsertOnSide(side: .Top, let offset):
+            let initCoords = board.getInsertionCoordinates(from: .Top, offset: offset)
+            let pieceCoords = switch board.fallCoordinates(
+                initialCoords: initCoords,
+                direction: .Bottom
+            ) {
+            case .Occupied:
+                initCoords
+            case .Piece(_, let touched):
+                touched
+                
+            default:
+                fatalError("Illegal move \(move.action)")
+            }
+            
+            if Self.countMaxRow(center: pieceCoords, board: board) >= self.minAligned {
+                self.state = .Finished(winner: move.player)
+            } else if board.countPieces() == board.columns * board.rows {
+                self.state = .Finished(winner: nil)
+            } else {
+                let next: PieceType = switch move.player {
+                case .A: .B
+                case .B: .A
+                }
+                self.state = .Playing(turn: next)
+            }
+        default:
+            fatalError("Illegal move \(move.action)")
+        }
+    } */
+    
+    @available(*, deprecated, message: "Old Rules design remnents")
+    internal static func countMaxRow(center: Coords, board: Board) -> Int {
+        var maxLength = 0
+        // For each "axis" (described as one direction)
+        for dir: (dc: Int, dr: Int) in [(1, 0), (0, 1), (1, 1), (-1, 1)] {
+            maxLength = max(maxLength, row(center: center, board: board, dir: dir).count)
+        }
+        
+        return maxLength
+    }
+    
+    private static func row(center: Coords, board: Board, dir: (dc: Int, dr: Int)) -> [Coords] {
+        guard let of = board[center]?.type else { return [] }
+        
+        var cells = [center]
+        
+        // Run in the two opposite directions of the axis
+        for (dc, dr) in [(dir.dc, dir.dr), (-dir.dc, -dir.dr)] {
+            var pos = center
+            
+            while true {
+                pos = Coords(pos.col + dc, pos.row + dr)
+                if !board.isInBounds(pos) || board[pos]?.type != of { break }
+                cells.append(pos)
+            }
+        }
+        
+        return cells
+    }
+}

Model/Sources/Model/Rules/Move.swift

@@ -0,0 +1,14 @@
+public struct Move: Equatable {
+    public let player: Player
+    public let action: Action
+    
+    public init(player: Player, action: Action) {
+        self.player = player
+        self.action = action
+    }
+    
+    public enum Action: Equatable {
+        case InsertOnSide(side: Direction, offset: Int)
+        case InsertAt(where: Coords)
+    }
+}

Model/Sources/Model/Rules/Rules.swift

@@ -0,0 +1,27 @@
+public protocol Rules {
+    // var state: GameState { get }
+
+    // var history: [Move] { get }
+
+    func createBoard() -> Board
+
+    func isValid(board: Board) -> Bool
+
+    func isValid(board: Board, move: Move) -> Bool
+
+    func validMoves(board: Board) -> [Move]
+
+    func validMoves(board: Board, for_player player: Player) -> [Move.Action]
+
+    func gameState(board: Board, last_turn: Player?) -> GameState
+    
+    // mutating func onMoveDone(move: Move, board: Board) -> Void
+}
+
+public enum GameState: Equatable {
+    case Playing(turn: Player)
+
+    case Win(winner: Player, cells: [Coords])
+    
+    case Draw
+}

Model/Sources/Model/Rules/TicTacToeRules.swift

@@ -0,0 +1,82 @@
+public struct TicTacToeRules: Rules {
+    private let players: [Player]
+    private let columns: Int, rows: Int, minAligned: Int
+    
+    public init(columns: Int, rows: Int, minAligned: Int = 3, players: [Player]) {
+        self.columns = columns
+        self.rows = rows
+        self.minAligned = minAligned
+        self.players = players
+    }
+    
+    public func createBoard() -> Board {
+        Board(columns: self.columns, rows: self.rows)!
+    }
+    
+    public func isValid(board: Board) -> Bool {
+        abs(board.countPieces(filter: { p in p.type == .A }) -
+            board.countPieces(filter: { p in p.type == .B })) <= 1
+    }
+    
+    public func isValid(board: Board, move: Move) -> Bool {
+        guard self.isValid(board: board) else { return false }
+        
+        if case .InsertAt(let coord) = move.action, board.isInBounds(coord) {
+            return true
+        }
+        
+        return false
+    }
+    
+    public func validMoves(board: Board) -> [Move] {
+        return self.players.flatMap { player in
+            self.validMoves(board: board, for_player: player).map { Move(player: player, action: $0) }
+        }
+    }
+    
+    private static func nextPlayer(board: Board) -> PieceType {
+        if board.countPieces(filter: { p in p.type == .A }) > board.countPieces(filter: { p in p.type == .B }) {
+            .B
+        } else {
+            .A
+        }
+    }
+    
+    public func validMoves(board: Board, for_player player: Player) -> [Move.Action] {
+        var moves: [Move.Action] = []
+        
+        for col in 0..<board.columns {
+            for row in 0..<board.rows {
+                if board[col, row] == nil {
+                    moves.append(.InsertAt(where: Coords(col, row)))
+                }
+            }
+        }
+        
+        return moves
+    }
+    
+    public func gameState(board: Board, last_turn: Player?) -> GameState {
+        FourInARowRules.rowOfLengthWin(board: board, last_turn: last_turn, minimum_aligned: self.minAligned, players: self.players)
+    }
+    
+    /* public mutating func onMoveDone(move: Move, board: Board) {
+        self.history.append(move)
+        
+        guard case .InsertAt(let coords) = move.action else {
+            fatalError("Illegal move \(move.action)")
+        }
+        
+        if FourInARowRules.countMaxRow(center: coords, board: board) >= self.minAligned {
+            self.state = .Finished(winner: move.player)
+        } else if board.countPieces() == board.columns * board.rows {
+            self.state = .Finished(winner: nil)
+        } else {
+            let next: PieceType = switch move.player {
+            case .A: .B
+            case .B: .A
+            }
+            self.state = .Playing(turn: next)
+        }
+    } */
+}

Model/Tests/ModelTests/EmptyBoardTests.swift

@@ -5,7 +5,7 @@ final class EmptyBoardTests: XCTestCase {
     private var board: Board!
     
     override func setUpWithError() throws {
-        super.setUp()
+        try super.setUpWithError()
         
         guard let board = Board(columns: 5, rows: 6) else {
             XCTFail()
@@ -32,7 +32,7 @@ final class EmptyBoardTests: XCTestCase {
     func testCustomSubscript() throws {
         for r in 0..<board.rows {
             for c in 0..<board.columns {
-                for p: Player in [.A, .B] {
+                for p: PieceType in [.A, .B] {
                     try self.setUpWithError()
                     
                     try self._testCustomSubscript(at: Coords(c, r), player: p)
@@ -43,19 +43,19 @@ final class EmptyBoardTests: XCTestCase {
         }
     }
     
-    private func _testCustomSubscript(at: Coords, player: Player) throws {
-        board[at] = Piece(owner: player)
+    private func _testCustomSubscript(at: Coords, player: PieceType) throws {
+        board[at] = Piece(type: player)
         
-        XCTAssertEqual(board[at]?.owner, player)
+        XCTAssertEqual(board[at]?.type, player)
     }
     
     func testCounts() throws {
-        board[1, 2] = Piece(owner: .B)
-        board[0, 2] = Piece(owner: .A)
-        board[1, 1] = Piece(owner: .A)
+        board[1, 2] = Piece(type: .B)
+        board[0, 2] = Piece(type: .A)
+        board[1, 1] = Piece(type: .A)
         
-        XCTAssertEqual(board.countPieces { piece in piece.owner == .A }, 2)
-        XCTAssertEqual(board.countPieces { piece in piece.owner == .B }, 1)
+        XCTAssertEqual(board.countPieces { piece in piece.type == .A }, 2)
+        XCTAssertEqual(board.countPieces { piece in piece.type == .B }, 1)
     }
     
     func testInsertsSides() throws {
@@ -129,9 +129,9 @@ final class EmptyBoardTests: XCTestCase {
             ] {
                 // ensure it works with any player
                 board[Coords(pair: pos)] = if (pos.0 + pos.1) & 1 == 1 {
-                    Piece(owner: .A)
+                    Piece(type: .A)
                 } else {
-                    Piece(owner: .B)
+                    Piece(type: .B)
                 }
             }
             

Model/Tests/ModelTests/FilledBoardTests.swift

@@ -15,9 +15,9 @@ final class FilledBoardTests: XCTestCase {
         for row in 0..<board.rows {
             for col in 0..<board.columns {
                 board[col, row] = if (row & 1) == 1 {
-                    Piece(owner: .A)
+                    Piece(type: .A)
                 } else {
-                    Piece(owner: .B)
+                    Piece(type: .B)
                 }
             }
         }

Model/Tests/ModelTests/Players/HumanPlayerTests.swift

@@ -0,0 +1,27 @@
+import XCTest
+@testable import Model
+
+final class HumanPlayerTests: XCTestCase {
+    func testInit() {
+        let p = HumanPlayer(name: "the name", piece_type: .B, callback: { _, _ in fatalError("NOOP") })
+        
+        XCTAssertEqual(p.name, "the name")
+        XCTAssertEqual(p.piece_type, .B)
+    }
+    
+    func testChoose() {
+        let board = Board(columns: 3, rows: 3)!
+        let moves: [Move.Action] = [.InsertAt(where: Coords(1, 2)), .InsertOnSide(side: .Left, offset: 1)]
+        
+        let player = HumanPlayer(name: "name", piece_type: .A, callback: {
+            moves2, board2 in
+            
+            XCTAssertEqual(moves2, moves)
+            XCTAssertEqual(board2, board)
+            
+            return .InsertOnSide(side: .Bottom, offset: 99)
+        })
+        
+        XCTAssertEqual(player.chooseMove(allowed_moves: moves, board: board), .InsertOnSide(side: .Bottom, offset: 99))
+    }
+}

Model/Tests/ModelTests/Players/RandomPlayerTests.swift

@@ -0,0 +1,27 @@
+import XCTest
+@testable import Model
+
+final class RandomPlayerTests: XCTestCase {
+    func testInit() {
+        for t in [PieceType.A, .B] {
+            let p = RandomPlayer(name: "the name", piece_type: t)
+            
+            XCTAssertEqual(p.name, "the name")
+            XCTAssertEqual(p.piece_type, t)
+        }
+    }
+    
+    func testChoose() {
+        let board = Board(columns: 3, rows: 3)!
+        let moves: [Move.Action] = [.InsertAt(where: Coords(1, 2)), .InsertOnSide(side: .Left, offset: 1)]
+        
+        let player = RandomPlayer(name: "name", piece_type: .A)
+        
+        // +5 test quality credits
+        for _ in 1...10 {
+            let choosen = player.chooseMove(allowed_moves: moves, board: board)
+            
+            XCTAssertNotNil(moves.firstIndex(of: choosen))
+        }
+    }
+}

Model/Tests/ModelTests/Rules/FourInARowRulesTests.swift

@@ -0,0 +1,137 @@
+import XCTest
+@testable import Model
+
+final class FourInARowRulesTests: XCTestCase {
+    private var rules: FourInARowRules!
+    private var board: Board!
+    private var players: [Player]!
+    
+    override func setUpWithError() throws {
+        try super.setUpWithError()
+        
+        self.players = [
+            Player(name: "A", piece_type: .A),
+            Player(name: "B", piece_type: .B)
+        ]
+        
+        guard let rules = FourInARowRules(columns: 3, rows: 3, minAligned: 3, players: players) else {
+            XCTFail()
+            return
+        }
+        
+        self.rules = rules
+        self.board = self.rules.createBoard()
+    }
+    
+    func testBoardIsValid() {
+        XCTAssertTrue(self.rules.isValid(board: self.board))
+    }
+    
+    func testInitialState() {
+        XCTAssertEqual(
+            self.rules.gameState(board: board, last_turn: nil),
+            GameState.Playing(turn: self.players.first!)
+        )
+    }
+    
+    func testMovesAreValid() {
+        for move in self.rules.validMoves(board: self.board) {
+            XCTAssertTrue(self.rules.isValid(board: board, move: move), "\(move)")
+        }
+    }
+    
+    func testMovesOfPlayerAreValid() throws {
+        for player in self.players {
+            try self.setUpWithError()
+            
+            try self._testMovesOfPlayerAreValid(player: player)
+            
+            try self.tearDownWithError()
+        }
+    }
+    
+    private func _testMovesOfPlayerAreValid(player: Player) throws {
+        for action in self.rules.validMoves(board: self.board, for_player: player) {
+            XCTAssertTrue(self.rules.isValid(board: board, move: Move(player: player, action: action)), "\(action)")
+        }
+    }
+    
+    func testOnMoveDone() {
+        let coord = Coords(1, board.rows - 1)
+        board[coord] = Piece(type: .A)
+        
+        XCTAssertEqual(
+            rules.gameState(board: board, last_turn: players.first!),
+            GameState.Playing(turn: players.last!)
+        )
+    }
+    
+    func testOnMoveDoneDraw() {
+        board[0, 0] = Piece(type: .A)
+        board[1, 0] = Piece(type: .A)
+        board[2, 0] = Piece(type: .B)
+        board[0, 1] = Piece(type: .B)
+        board[1, 1] = Piece(type: .B)
+        board[2, 1] = Piece(type: .A)
+        board[0, 2] = Piece(type: .A)
+        board[1, 2] = Piece(type: .A)
+        
+        board[2, 2] = Piece(type: .B)
+        
+        XCTAssertTrue(rules.isValid(board: board))
+        XCTAssertEqual(rules.gameState(board: board, last_turn: players.last!), GameState.Draw)
+    }
+    
+    func testOnMoveDoneWin() {
+        board[0, 0] = Piece(type: .A)
+        board[1, 0] = Piece(type: .A)
+        board[2, 0] = Piece(type: .A) //
+        board[0, 1] = Piece(type: .B)
+        board[1, 1] = Piece(type: .B)
+        board[2, 1] = Piece(type: .A)
+        board[0, 2] = Piece(type: .A)
+        board[1, 2] = Piece(type: .A)
+        board[2, 2] = Piece(type: .B)
+        
+        XCTAssertTrue(rules.isValid(board: board))
+                
+        XCTAssertEqual(
+            rules.gameState(board: board, last_turn: players.first!),
+            GameState.Win(winner: players.first!, cells: [Coords(0, 0), Coords(1, 0), Coords(2, 0)])
+        )
+    }
+    
+    func testCountMaxRow() throws {
+        for (coords, expected) in [
+            (Coords(1, 0), 3),
+            (Coords(0, 1), 2),
+            (Coords(0, 2), 2),
+            (Coords(1, 1), 3),
+            (Coords(2, 2), 3),
+            (Coords(2, 1), 2),
+        ] {
+            try self.setUpWithError()
+            
+            // AAA
+            // BAB
+            // BBA
+            board[0, 0] = Piece(type: .A)
+            board[1, 0] = Piece(type: .A)
+            board[2, 0] = Piece(type: .A)
+            board[0, 1] = Piece(type: .B)
+            board[1, 1] = Piece(type: .A)
+            board[2, 1] = Piece(type: .B)
+            board[0, 2] = Piece(type: .B)
+            board[1, 2] = Piece(type: .B)
+            board[2, 2] = Piece(type: .A)
+            
+            self._testCountMaxRow(coords: coords, expected: expected)
+            
+            try self.tearDownWithError()
+        }
+    }
+    
+    private func _testCountMaxRow(coords: Coords, expected: Int) {
+        XCTAssertEqual(FourInARowRules.countMaxRow(center: coords, board: board), expected, "\(coords)")
+    }
+}