Add didCheckKing delegate method to unit tests

Author: pdil

Sources/ChessKit/Board.swift

@@ -8,7 +8,7 @@
 /// as pawn promotions and end results.
 public protocol BoardDelegate: AnyObject, Sendable {
   func didPromote(with move: Move)
-  func didCheckKing(ofColor: Piece.Color)
+  func didCheckKing(ofColor color: Piece.Color)
   func didEnd(with result: Board.EndResult)
 }
 
@@ -233,7 +233,7 @@ public struct Board: Sendable {
     } else if positionHashCounts[position.hashValue] == 3 {
       delegate?.didEnd(with: .draw(.repetition))
     } else if checkState == .check {
-      delegate?.didCheckKing(ofColor: processedMove.piece.color)
+      delegate?.didCheckKing(ofColor: processedMove.piece.color.opposite)
     }
 
     // pawn promotion

Tests/ChessKitTests/BoardTests.swift

@@ -352,8 +352,23 @@ final class BoardTests: XCTestCase {
 
   func testCheckMove() {
     var board = Board(position: .init(fen: "k7/7R/8/8/8/8/K7/8 w - - 0 1")!)
+
+    nonisolated(unsafe) var expectation: XCTestExpectation? = self.expectation(description: "Board returns check result")
+
+    let delegate = MockBoardDelegate(didCheckKing: { color in
+      if color == .black {
+        expectation?.fulfill()
+        expectation = nil
+      } else {
+        XCTFail()
+      }
+    })
+
+    board.delegate = delegate
     let move = board.move(pieceAt: .h7, to: .h8)
     XCTAssertEqual(move?.checkState, .check)
+
+    waitForExpectations(timeout: 1.0)
   }
 
   func testCheckmateMove() {

Tests/ChessKitTests/Utilities/MockBoardDelegate.swift

@@ -7,22 +7,25 @@
 
 final class MockBoardDelegate: BoardDelegate {
   private let didPromote: (@Sendable (Move) -> Void)?
+  private let didCheckKing: (@Sendable (Piece.Color) -> Void)?
   private let didEnd: (@Sendable (Board.EndResult) -> Void)?
 
   init(
     didPromote: (@Sendable (Move) -> Void)? = nil,
+    didCheckKing: (@Sendable (Piece.Color) -> Void)? = nil,
     didEnd: (@Sendable (Board.EndResult) -> Void)? = nil
   ) {
     self.didPromote = didPromote
+    self.didCheckKing = didCheckKing
     self.didEnd = didEnd
   }
 
   func didPromote(with move: Move) {
     didPromote?(move)
   }
 
-  func didCheckKing(ofColor: Piece.Color) {
-
+  func didCheckKing(ofColor color: Piece.Color) {
+    didCheckKing?(color)
   }
 
   func didEnd(with result: Board.EndResult) {