refactor(tests): NCS-23 improve CommandInvoker tests for clarity and coverage

modules/rule/src/main/scala/de/nowchess/rules/sets/DefaultRules.scala

@@ -124,6 +124,14 @@ object DefaultRules extends RuleSet:
 
   // ── Castling ───────────────────────────────────────────────────────
 
+  private case class CastlingMove(
+    kingFromAlg: String,
+    kingToAlg: String,
+    middleAlg: String,
+    rookFromAlg: String,
+    moveType: MoveType
+  )
+
   private def castlingCandidates(
     context: GameContext,
     from: Square,
@@ -139,9 +147,9 @@ object DefaultRules extends RuleSet:
     else
       val moves = scala.collection.mutable.ListBuffer[Move]()
       addCastleMove(context, moves, context.castlingRights.whiteKingSide,
-        "e1", "g1", "f1", "h1", MoveType.CastleKingside)
+        CastlingMove("e1", "g1", "f1", "h1", MoveType.CastleKingside))
       addCastleMove(context, moves, context.castlingRights.whiteQueenSide,
-        "e1", "c1", "d1", "a1", MoveType.CastleQueenside)
+        CastlingMove("e1", "c1", "d1", "a1", MoveType.CastleQueenside))
       moves.toList
 
   private def blackCastles(context: GameContext, from: Square): List[Move] =
@@ -150,29 +158,25 @@ object DefaultRules extends RuleSet:
     else
       val moves = scala.collection.mutable.ListBuffer[Move]()
       addCastleMove(context, moves, context.castlingRights.blackKingSide,
-        "e8", "g8", "f8", "h8", MoveType.CastleKingside)
+        CastlingMove("e8", "g8", "f8", "h8", MoveType.CastleKingside))
       addCastleMove(context, moves, context.castlingRights.blackQueenSide,
-        "e8", "c8", "d8", "a8", MoveType.CastleQueenside)
+        CastlingMove("e8", "c8", "d8", "a8", MoveType.CastleQueenside))
       moves.toList
 
   private def addCastleMove(
     context: GameContext,
     moves: scala.collection.mutable.ListBuffer[Move],
     castlingRight: Boolean,
-    kingFromAlg: String,
-    kingToAlg: String,
-    middleAlg: String,
-    rookFromAlg: String,
-    moveType: MoveType
+    castlingMove: CastlingMove
   ): Unit =
     if castlingRight then
-      val clearSqs = List(middleAlg, kingToAlg).flatMap(Square.fromAlgebraic)
+      val clearSqs = List(castlingMove.middleAlg, castlingMove.kingToAlg).flatMap(Square.fromAlgebraic)
       if squaresEmpty(context.board, clearSqs) then
         for
-          kf <- Square.fromAlgebraic(kingFromAlg)
-          km <- Square.fromAlgebraic(middleAlg)
-          kt <- Square.fromAlgebraic(kingToAlg)
-          rf <- Square.fromAlgebraic(rookFromAlg)
+          kf <- Square.fromAlgebraic(castlingMove.kingFromAlg)
+          km <- Square.fromAlgebraic(castlingMove.middleAlg)
+          kt <- Square.fromAlgebraic(castlingMove.kingToAlg)
+          rf <- Square.fromAlgebraic(castlingMove.rookFromAlg)
         do
           val color = context.turn
           val kingPresent = context.board.pieceAt(kf).exists(p => p.color == color && p.pieceType == PieceType.King)
@@ -183,7 +187,7 @@ object DefaultRules extends RuleSet:
             !isAttackedBy(context.board, kt, color.opposite)
 
           if kingPresent && rookPresent && squaresSafe then
-            moves += Move(kf, kt, moveType)
+            moves += Move(kf, kt, castlingMove.moveType)
 
   private def squaresEmpty(board: Board, squares: List[Square]): Boolean =
     squares.forall(sq => board.pieceAt(sq).isEmpty)