Some refactor and tests

Sources/Engine/Pieces/CommonMoves.swift

@@ -1,11 +1,6 @@
-protocol DiagonalMoves {
+fileprivate func getDirectionalMoves(from pos: Square.Position, with dir: [(Int8, Int8)]) -> [Square.Position] {
-    func getDiagonalMoves(from pos: Square.Position) -> [Square.Position]
-}
-
-extension DiagonalMoves {
-    func getDiagonalMoves(from pos: Square.Position) -> [Square.Position] {
     var squares = [Square.Position]()
-        for i: (Int8, Int8) in [(1, -1), (1, 1), (-1, 1), (-1, -1)] {
+    for i: (Int8, Int8) in dir {
         var currentSquare = pos + i
         while currentSquare.index != nil {
             squares.append(currentSquare)
@@ -13,6 +8,14 @@ extension DiagonalMoves {
         }
     }
     return squares
+}
+protocol DiagonalMoves {
+    func getDiagonalMoves(from pos: Square.Position) -> [Square.Position]
+}
+
+extension DiagonalMoves {
+    func getDiagonalMoves(from pos: Square.Position) -> [Square.Position] {
+        getDirectionalMoves(from: pos, with: [(1, -1), (1, 1), (-1, 1), (-1, -1)])
     }
 }
 
@@ -22,14 +25,6 @@ protocol LinearMoves {
 
 extension LinearMoves {
     func getLinearMoves(from pos: Square.Position) -> [Square.Position] {
-        var squares = [Square.Position]()
+        getDirectionalMoves(from: pos, with: [(1, 0), (0, 1), (-1, 0), (0, -1)])
-        for i: (Int8, Int8) in [(1, 0), (0, 1), (-1, 0), (0, -1)] {
-            var currentSquare = pos + i
-            while currentSquare.index != nil {
-                squares.append(currentSquare)
-                currentSquare += i 
-            }
-        }
-        return squares
     }
 }

Sources/Engine/Pieces/King.swift

@@ -10,7 +10,16 @@ final class King: Piece {
 	var position: Square.Position
 
 	var pseudoLegalPositions: [Square.Position] {
-		return []
+		[
+			position + (1, 0),
+			position + (1, 1),
+			position + (0, 1),
+			position + (-1, 1),
+			position + (-1, 0),
+			position + (-1, -1),
+			position + (0, -1),
+			position + (1, -1)
+		].filter {$0.index != nil}
 	}
 
 	var legalPositions: [Square.Position] {

Sources/Engine/Pieces/Knight.swift

@@ -10,17 +10,16 @@ final class Knight: Piece {
 	var position: Square.Position
 
 	var pseudoLegalPositions: [Square.Position] {
-		let directions: [Square.Position] = [
+		[
-			.init(rank: position.rank + 2, file: position.file + 1),
+			position + (2, 1),
-			.init(rank: position.rank + 2, file: position.file - 1),
+			position + (2, -1),
-			.init(rank: position.rank - 2, file: position.file + 1),
+			position + (-2, 1),
-			.init(rank: position.rank - 2, file: position.file - 1),
+			position + (-2, -1),
-			.init(rank: position.rank + 1, file: position.file + 2),
+			position + (1, 2),
-			.init(rank: position.rank + 1, file: position.file - 2),
+			position + (1, -2),
-			.init(rank: position.rank - 1, file: position.file + 2),
+			position + (-1, 2),
-			.init(rank: position.rank - 1, file: position.file - 2)
+			position + (-1, -2)
-		]
+		].filter { $0.index != nil }
-		return directions.filter { $0.index != nil }
 	}
 
 	var legalPositions: [Square.Position] {

Sources/Engine/Pieces/Pawn.swift

@@ -5,15 +5,12 @@ final class Pawn: Piece {
 	var position: Square.Position
 	var pseudoLegalPositions: [Square.Position] {
 		let sign: Int8 = color == .Black ? -1 : 1
-		let rank = Int8(position.rank)
+		return [
-		let directions: [Square.Position] = [
+			position + (1 * sign, 0),
-			.init(rank: rank + 1 * sign, file: position.file),
+			position + (2 * sign, 0),
-			.init(rank: rank + 2 * sign, file: position.file),
+			position + (1 * sign, 1),
-			.init(rank: rank + 1 * sign, file: position.file + 1),
+			position + (1 * sign, -1)
-			.init(rank: rank + 1 * sign, file: position.file - 1)
+		].filter { $0.index != nil }
-		]
-		// TODO: Handle en passant
-		return directions.filter { $0.index != nil }
 	}
 	var legalPositions: [Square.Position] {
 		pseudoLegalPositions.filter { isLegal(on: $0) }

Tests/EngineTests/EngineTests.swift

@@ -14,7 +14,8 @@ final class EngineTests: XCTestCase {
 				rank -= 1
 			}
 			let pos: Square.Position = .init(rank: rank, file: file)
-			XCTAssertTrue(pos.index == Int(i), "Expected \(i) got \(pos.index!)")
+			XCTAssertTrue(
+				pos.index == Int(i), "Expected \(i) got \(pos.index!)")
 		}
 	}
 	func testDiagonalMoves() throws {
@@ -57,6 +58,53 @@ final class EngineTests: XCTestCase {
 		]
 		XCTAssertEqual(result, r.pseudoLegalPositions)
 	}
+
+	func testKingMoves() throws {
+		let k: King = .init(color: .White, on: .init(rank: 2, file: 8))
+		let result = [
+			Square.Position(rank: 3, file: 8),
+			Square.Position(rank: 1, file: 8),
+			Square.Position(rank: 1, file: 7),
+			Square.Position(rank: 2, file: 7),
+			Square.Position(rank: 3, file: 7),
+		]
+		XCTAssertEqual(result, k.pseudoLegalPositions)
+	}
+
+	func testKnightMoves() throws {
+		let n: Knight = .init(color: .White, on: .init(rank: 4, file: 4))
+		let result = [
+			Square.Position(rank: 6, file: 5),
+			Square.Position(rank: 6, file: 3),
+			Square.Position(rank: 2, file: 5),
+			Square.Position(rank: 2, file: 3),
+			Square.Position(rank: 5, file: 6),
+			Square.Position(rank: 5, file: 2),
+			Square.Position(rank: 3, file: 6),
+			Square.Position(rank: 3, file: 2),
+		]
+		XCTAssertEqual(result, n.pseudoLegalPositions)
+	}
+
+	func testPawnMoves() throws {
+		let pw: Pawn = .init(color: .White, on: .init(rank: 4, file: 4))
+		var result = [
+			Square.Position(rank: 5, file: 4),
+			Square.Position(rank: 6, file: 4),
+			Square.Position(rank: 5, file: 5),
+			Square.Position(rank: 5, file: 3),
+		]
+		XCTAssertEqual(result, pw.pseudoLegalPositions)
+		let pb: Pawn = .init(color: .Black, on: .init(rank: 4, file: 4))
+		result = [
+			Square.Position(rank: 3, file: 4),
+			Square.Position(rank: 2, file: 4),
+			Square.Position(rank: 3, file: 5),
+			Square.Position(rank: 3, file: 3),
+		]
+		XCTAssertEqual(result, pb.pseudoLegalPositions)
+	}
+
 	// func testBoard() throws {
 	// 	let board = Board()
 	// }