UTests pass with Pathfinder2D

Gameboard.ShogiUI.BoardState/Pieces/Bishop.cs

@@ -0,0 +1,47 @@
+using PathFinding;
+using System.Collections.Generic;
+using System.Linq;
+using System.Numerics;
+
+namespace Gameboard.ShogiUI.BoardState.Pieces
+{
+  public class Bishop : Piece
+  {
+    private static readonly List<Path> MoveSet = new List<Path>(4)
+    {
+      new Path(Direction.UpLeft, Distance.MultiStep),
+      new Path(Direction.UpRight, Distance.MultiStep),
+      new Path(Direction.DownLeft, Distance.MultiStep),
+      new Path(Direction.DownRight, Distance.MultiStep)
+    };
+    private static readonly List<Path> PromotedMoveSet = new List<Path>(8)
+    {
+      new Path(Direction.Up),
+      new Path(Direction.Left),
+      new Path(Direction.Right),
+      new Path(Direction.Down),
+      new Path(Direction.UpLeft, Distance.MultiStep),
+      new Path(Direction.UpRight, Distance.MultiStep),
+      new Path(Direction.DownLeft, Distance.MultiStep),
+      new Path(Direction.DownRight, Distance.MultiStep)
+    };
+    public Bishop(WhichPlayer owner) : base(WhichPiece.Bishop, owner)
+    {
+      // TODO: If this strat works out, we can do away with the Direction class entirely.
+      PromotedMoveSet.AddRange(MoveSet);
+    }
+
+    public override Piece DeepClone()
+    {
+      var clone = new Bishop(Owner);
+      if (IsPromoted) clone.Promote();
+      return clone;
+    }
+
+    public override ICollection<Path> GetPaths()
+    {
+      var moveSet = IsPromoted ? PromotedMoveSet : MoveSet;
+      return Owner == WhichPlayer.Player1 ? moveSet : moveSet.Select(_ => new Path(Vector2.Negate(_.Direction), _.Distance)).ToList();
+    }
+  }
+}