From 86552b52bd9e40e4053b1d9c5af08dc77fff595c Mon Sep 17 00:00:00 2001
From: Janis <janis.e.20@gmx.de>
Date: Mon, 23 Mar 2026 21:34:24 +0100
Subject: [PATCH] test: add failing GameRulesTest for check/checkmate/stalemate

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 .../nowchess/chess/logic/GameRulesTest.scala  | 88 +++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 modules/core/src/test/scala/de/nowchess/chess/logic/GameRulesTest.scala

diff --git a/modules/core/src/test/scala/de/nowchess/chess/logic/GameRulesTest.scala b/modules/core/src/test/scala/de/nowchess/chess/logic/GameRulesTest.scala
new file mode 100644
index 0000000..dfcd5f7
--- /dev/null
+++ b/modules/core/src/test/scala/de/nowchess/chess/logic/GameRulesTest.scala
@@ -0,0 +1,88 @@
+package de.nowchess.chess.logic
+
+import de.nowchess.api.board.*
+import org.scalatest.funsuite.AnyFunSuite
+import org.scalatest.matchers.should.Matchers
+
+class GameRulesTest extends AnyFunSuite with Matchers:
+
+  private def sq(f: File, r: Rank): Square = Square(f, r)
+  private def board(entries: (Square, Piece)*): Board = Board(entries.toMap)
+
+  // ──── isInCheck ──────────────────────────────────────────────────────
+
+  test("isInCheck: king attacked by enemy rook on same rank"):
+    // White King E1, Black Rook A1 — rook slides along rank 1 to E1
+    val b = board(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.A, Rank.R1) -> Piece.BlackRook
+    )
+    GameRules.isInCheck(b, Color.White) shouldBe true
+
+  test("isInCheck: king not attacked"):
+    // Black Rook A3 does not cover E1
+    val b = board(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.A, Rank.R3) -> Piece.BlackRook
+    )
+    GameRules.isInCheck(b, Color.White) shouldBe false
+
+  test("isInCheck: no king on board returns false"):
+    val b = board(sq(File.A, Rank.R1) -> Piece.BlackRook)
+    GameRules.isInCheck(b, Color.White) shouldBe false
+
+  // ──── legalMoves ─────────────────────────────────────────────────────
+
+  test("legalMoves: move that exposes own king to rook is excluded"):
+    // White King E1, White Rook E4 (pinned on E-file), Black Rook E8
+    // Moving the White Rook off the E-file would expose the king
+    val b = board(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.E, Rank.R4) -> Piece.WhiteRook,
+      sq(File.E, Rank.R8) -> Piece.BlackRook
+    )
+    val moves = GameRules.legalMoves(b, Color.White)
+    moves should not contain (sq(File.E, Rank.R4) -> sq(File.D, Rank.R4))
+
+  test("legalMoves: move that blocks check is included"):
+    // White King E1 in check from Black Rook E8; White Rook A5 can interpose on E5
+    val b = board(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.A, Rank.R5) -> Piece.WhiteRook,
+      sq(File.E, Rank.R8) -> Piece.BlackRook
+    )
+    val moves = GameRules.legalMoves(b, Color.White)
+    moves should contain(sq(File.A, Rank.R5) -> sq(File.E, Rank.R5))
+
+  // ──── gameStatus ──────────────────────────────────────────────────────
+
+  test("gameStatus: checkmate returns Mated"):
+    // White Qh8, Ka6; Black Ka8
+    // Qh8 attacks Ka8 along rank 8; all escape squares covered (spec-verified position)
+    val b = board(
+      sq(File.H, Rank.R8) -> Piece.WhiteQueen,
+      sq(File.A, Rank.R6) -> Piece.WhiteKing,
+      sq(File.A, Rank.R8) -> Piece.BlackKing
+    )
+    GameRules.gameStatus(b, Color.Black) shouldBe PositionStatus.Mated
+
+  test("gameStatus: stalemate returns Drawn"):
+    // White Qb6, Kc6; Black Ka8
+    // Black king has no legal moves and is not in check (spec-verified position)
+    val b = board(
+      sq(File.B, Rank.R6) -> Piece.WhiteQueen,
+      sq(File.C, Rank.R6) -> Piece.WhiteKing,
+      sq(File.A, Rank.R8) -> Piece.BlackKing
+    )
+    GameRules.gameStatus(b, Color.Black) shouldBe PositionStatus.Drawn
+
+  test("gameStatus: king in check with legal escape returns InCheck"):
+    // White Ra8 attacks Black Ke8 along rank 8; king can escape to d7, e7, f7
+    val b = board(
+      sq(File.A, Rank.R8) -> Piece.WhiteRook,
+      sq(File.E, Rank.R8) -> Piece.BlackKing
+    )
+    GameRules.gameStatus(b, Color.Black) shouldBe PositionStatus.InCheck
+
+  test("gameStatus: normal starting position returns Normal"):
+    GameRules.gameStatus(Board.initial, Color.White) shouldBe PositionStatus.Normal