Add more tests

lib/src/attacks.dart

@@ -3,25 +3,25 @@ import './models.dart';
 
 /// Gets squares attacked or defended by a king on [Square].
 SquareSet kingAttacks(Square square) {
-  return _kingAttacks[square.value];
+  return _kingAttacks[square];
 }
 
 /// Gets squares attacked or defended by a knight on [Square].
 SquareSet knightAttacks(Square square) {
-  return _knightAttacks[square.value];
+  return _knightAttacks[square];
 }
 
 /// Gets squares attacked or defended by a pawn of the given [Side] on [Square].
 SquareSet pawnAttacks(Side side, Square square) {
-  return _pawnAttacks[side]![square.value];
+  return _pawnAttacks[side]![square];
 }
 
 /// Gets squares attacked or defended by a bishop on [Square], given `occupied`
 /// squares.
 SquareSet bishopAttacks(Square square, SquareSet occupied) {
   final bit = SquareSet.fromSquare(square);
-  return _hyperbola(bit, _diagRange[square.value], occupied) ^
-      _hyperbola(bit, _antiDiagRange[square.value], occupied);
+  return _hyperbola(bit, _diagRange[square], occupied) ^
+      _hyperbola(bit, _antiDiagRange[square], occupied);
 }
 
 /// Gets squares attacked or defended by a rook on [Square], given `occupied`
@@ -84,7 +84,7 @@ SquareSet between(Square a, Square b) => ray(a, b)
 SquareSet _computeRange(Square square, List<int> deltas) {
   SquareSet range = SquareSet.empty;
   for (final delta in deltas) {
-    final sq = square.value + delta;
+    final sq = square + delta;
     if (0 <= sq && sq < 64 && (square.file - Square(sq).file).abs() <= 2) {
       range = range.withSquare(Square(sq));
     }
@@ -95,7 +95,7 @@ SquareSet _computeRange(Square square, List<int> deltas) {
 List<T> _tabulate<T>(T Function(Square square) f) {
   final List<T> table = [];
   for (final square in Square.values) {
-    table.insert(square.value, f(square));
+    table.insert(square, f(square));
   }
   return table;
 }
@@ -137,11 +137,11 @@ SquareSet _hyperbola(SquareSet bit, SquareSet range, SquareSet occupied) {
   return (forward ^ reverse.flipVertical()) & range;
 }
 
-SquareSet _fileAttacks(Square square, SquareSet occupied) => _hyperbola(
-    SquareSet.fromSquare(square), _fileRange[square.value], occupied);
+SquareSet _fileAttacks(Square square, SquareSet occupied) =>
+    _hyperbola(SquareSet.fromSquare(square), _fileRange[square], occupied);
 
 SquareSet _rankAttacks(Square square, SquareSet occupied) {
-  final range = _rankRange[square.value];
+  final range = _rankRange[square];
   final bit = SquareSet.fromSquare(square);
   SquareSet forward = occupied & range;
   SquareSet reverse = forward.mirrorHorizontal();

lib/src/models.dart

@@ -84,6 +84,17 @@ extension type const File._(int value) implements int {
   /// Gets the chessboard [File] from a file index between 0 and 7.
   const File(this.value) : assert(value >= 0 && value < 8);
 
+  /// Constructs a [File] from an algebraic notation, such as 'a', 'b', 'c', etc.
+  ///
+  /// Throws a [FormatException] if the algebraic notation is invalid.
+  factory File.fromAlgebraic(String algebraic) {
+    final file = algebraic.codeUnitAt(0) - 97;
+    if (file < 0 || file > 7) {
+      throw FormatException('Invalid algebraic notation: $algebraic');
+    }
+    return File(file);
+  }
+
   static const a = File(0);
   static const b = File(1);
   static const c = File(2);
@@ -93,6 +104,7 @@ extension type const File._(int value) implements int {
   static const g = File(6);
   static const h = File(7);
 
+  /// All files in ascending order.
   static const values = [a, b, c, d, e, f, g, h];
 
   static const _names = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'];
@@ -120,6 +132,17 @@ extension type const Rank._(int value) implements int {
   /// Gets the chessboard [Rank] from a rank index between 0 and 7.
   const Rank(this.value) : assert(value >= 0 && value < 8);
 
+  /// Constructs a [Rank] from an algebraic notation, such as '1', '2', '3', etc.
+  ///
+  /// Throws a [FormatException] if the algebraic notation is invalid.
+  factory Rank.fromAlgebraic(String algebraic) {
+    final rank = algebraic.codeUnitAt(0) - 49;
+    if (rank < 0 || rank > 7) {
+      throw FormatException('Invalid algebraic notation: $algebraic');
+    }
+    return Rank(rank);
+  }
+
   static const first = Rank(0);
   static const second = Rank(1);
   static const third = Rank(2);
@@ -129,6 +152,7 @@ extension type const Rank._(int value) implements int {
   static const seventh = Rank(6);
   static const eighth = Rank(7);
 
+  /// All ranks in ascending order.
   static const values = [
     first,
     second,
@@ -167,9 +191,14 @@ extension type const Square._(int value) implements int {
   const Square(this.value) : assert(value >= 0 && value < 64);
 
   /// Constructs a [Square] from an algebraic notation, such as 'a1', 'b2', etc.
+  ///
+  /// Throws a [FormatException] if the algebraic notation is invalid.
   factory Square.fromAlgebraic(String algebraic) {
     final file = algebraic.codeUnitAt(0) - 97;
     final rank = algebraic.codeUnitAt(1) - 49;
+    if (file < 0 || file > 7 || rank < 0 || rank > 7) {
+      throw FormatException('Invalid algebraic notation: $algebraic');
+    }
     return Square(rank * 8 + file);
   }
 

lib/src/position.dart

@@ -852,7 +852,7 @@ abstract class Position<T extends Position<T>> {
     if (piece.role == Role.pawn) {
       pseudo = pawnAttacks(turn, square) & board.bySide(turn.opposite);
       final delta = turn == Side.white ? 8 : -8;
-      final step = square.value + delta;
+      final step = square + delta;
       if (0 <= step && step < 64 && !board.occupied.has(Square(step))) {
         pseudo = pseudo.withSquare(Square(step));
         final canDoubleStep =
@@ -995,7 +995,7 @@ abstract class Position<T extends Position<T>> {
   /// Returns the [CastlingSide] or `null` if the move is a drop move.
   CastlingSide? _getCastlingSide(Move move) {
     if (move case NormalMove(from: final from, to: final to)) {
-      final delta = to.value - from.value;
+      final delta = to - from;
       if (delta.abs() != 2 && !board.bySide(turn).has(to)) {
         return null;
       }

lib/src/square_set.dart

@@ -22,7 +22,7 @@ extension type const SquareSet(int value) {
   /// Creates a [SquareSet] from several [Square]s.
   SquareSet.fromSquares(Iterable<Square> squares)
       : value = squares
-            .map((square) => 1 << square.value)
+            .map((square) => 1 << square)
             .fold(0, (left, right) => left | right);
 
   /// Create a [SquareSet] containing all squares of the given rank.
@@ -135,7 +135,7 @@ extension type const SquareSet(int value) {
 
   /// Returns true if the [SquareSet] contains the given [square].
   bool has(Square square) {
-    return value & (1 << square.value) != 0;
+    return value & (1 << square) != 0;
   }
 
   /// Returns true if the square set has any square in the [other] square set.
@@ -146,17 +146,17 @@ extension type const SquareSet(int value) {
 
   /// Returns a new [SquareSet] with the given [square] added.
   SquareSet withSquare(Square square) {
-    return SquareSet(value | (1 << square.value));
+    return SquareSet(value | (1 << square));
   }
 
   /// Returns a new [SquareSet] with the given [square] removed.
   SquareSet withoutSquare(Square square) {
-    return SquareSet(value & ~(1 << square.value));
+    return SquareSet(value & ~(1 << square));
   }
 
   /// Removes [Square] if present, or put it if absent.
   SquareSet toggleSquare(Square square) {
-    return SquareSet(value ^ (1 << square.value));
+    return SquareSet(value ^ (1 << square));
   }
 
   /// Returns a new [SquareSet] with its first [Square] removed.