refactor(tests): improve CommandInvoker tests for clarity and coverage

modules/core/src/main/scala/de/nowchess/chess/engine/GameEngine.scala

@@ -163,13 +163,15 @@ class GameEngine(
     moves.foreach: move =>
       if error.isEmpty then
         handleParsedMove(move.from, move.to)
-        move.moveType match
+
+        move.moveType match {
           case MoveType.Promotion(pp) =>
             if pendingPromotion.isDefined then
               completePromotion(pp)
             else
               error = Some(s"Promotion required for move ${move.from}${move.to}")
           case _ => ()
+        }
     error match
       case Some(err) =>
         currentContext = savedContext

modules/core/src/test/scala/de/nowchess/chess/command/CommandInvokerBranchTest.scala

@@ -27,33 +27,30 @@ class CommandInvokerBranchTest extends AnyFunSuite with Matchers:
       previousContext = Some(GameContext.initial)
     )
 
-  test("CommandInvoker.execute() with failing command returns false"):
+  test("execute rejects failing commands and keeps history unchanged"):
     val invoker = new CommandInvoker()
     val cmd = FailingCommand()
     invoker.execute(cmd) shouldBe false
     invoker.history.size shouldBe 0
     invoker.getCurrentIndex shouldBe -1
 
-  test("CommandInvoker.execute() does not add failed command to history"):
-    val invoker = new CommandInvoker()
     val failingCmd = FailingCommand()
     val successCmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
     invoker.execute(failingCmd) shouldBe false
     invoker.history.size shouldBe 0
     invoker.execute(successCmd) shouldBe true
     invoker.history.size shouldBe 1
-    invoker.history(0) shouldBe successCmd
+    invoker.history.head shouldBe successCmd
 
-  test("CommandInvoker.undo() returns false when currentIndex < 0"):
+  test("undo redo and history trimming cover all command state transitions"):
+    {
       val invoker = new CommandInvoker()
       invoker.undo() shouldBe false
-
-  test("CommandInvoker.undo() returns false when empty history"):
-    val invoker = new CommandInvoker()
       invoker.canUndo shouldBe false
       invoker.undo() shouldBe false
+    }
 
-  test("CommandInvoker.undo() returns false when currentIndex >= history size"):
+    {
       val invoker = new CommandInvoker()
       val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
       val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
@@ -61,47 +58,43 @@ class CommandInvokerBranchTest extends AnyFunSuite with Matchers:
       invoker.execute(cmd2)
       invoker.undo()
       invoker.undo()
-    invoker.undo()
+      invoker.undo() shouldBe false
+    }
 
-  test("CommandInvoker.undo() returns false when command.undo() fails"):
+    {
       val invoker = new CommandInvoker()
-    val failingCmd = ConditionalFailCommand(shouldFailOnUndo = true)
-    invoker.execute(failingCmd) shouldBe true
+      val failingUndoCmd = ConditionalFailCommand(shouldFailOnUndo = true)
+      invoker.execute(failingUndoCmd) shouldBe true
       invoker.canUndo shouldBe true
       invoker.undo() shouldBe false
       invoker.getCurrentIndex shouldBe 0
+    }
 
-  test("CommandInvoker.undo() returns true when command.undo() succeeds"):
+    {
       val invoker = new CommandInvoker()
-    val successCmd = ConditionalFailCommand(shouldFailOnUndo = false)
-    invoker.execute(successCmd) shouldBe true
+      val successUndoCmd = ConditionalFailCommand()
+      invoker.execute(successUndoCmd) shouldBe true
       invoker.undo() shouldBe true
       invoker.getCurrentIndex shouldBe -1
+    }
 
-  test("CommandInvoker.redo() returns false when nothing to redo"):
+    {
       val invoker = new CommandInvoker()
       invoker.redo() shouldBe false
+    }
 
-  test("CommandInvoker.redo() returns false when at end of history"):
+    {
       val invoker = new CommandInvoker()
       val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
       invoker.execute(cmd)
       invoker.canRedo shouldBe false
       invoker.redo() shouldBe false
+    }
 
-  test("CommandInvoker.redo() returns false when currentIndex + 1 >= size"):
+    {
       val invoker = new CommandInvoker()
       val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
-    invoker.execute(cmd1)
-    invoker.execute(cmd2)
-    invoker.canRedo shouldBe false
-    invoker.redo() shouldBe false
-
-  test("CommandInvoker.redo() returns false when command.execute() fails"):
-    val invoker = new CommandInvoker()
-    val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val redoFailCmd = ConditionalFailCommand(shouldFailOnExecute = false)
+      val redoFailCmd = ConditionalFailCommand()
       invoker.execute(cmd1)
       invoker.execute(redoFailCmd)
       invoker.undo()
@@ -109,16 +102,18 @@ class CommandInvokerBranchTest extends AnyFunSuite with Matchers:
       redoFailCmd.shouldFailOnExecute = true
       invoker.redo() shouldBe false
       invoker.getCurrentIndex shouldBe 0
+    }
 
-  test("CommandInvoker.redo() returns true when command.execute() succeeds"):
+    {
       val invoker = new CommandInvoker()
       val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
       invoker.execute(cmd) shouldBe true
       invoker.undo() shouldBe true
       invoker.redo() shouldBe true
       invoker.getCurrentIndex shouldBe 0
+    }
 
-  test("CommandInvoker.execute() discards redo history via while loop"):
+    {
       val invoker = new CommandInvoker()
       val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
       val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
@@ -131,8 +126,9 @@ class CommandInvokerBranchTest extends AnyFunSuite with Matchers:
       invoker.canRedo shouldBe false
       invoker.history.size shouldBe 2
       invoker.history(1) shouldBe cmd3
+    }
 
-  test("CommandInvoker.execute() discards multiple redo commands"):
+    {
       val invoker = new CommandInvoker()
       val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
       val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
@@ -149,14 +145,4 @@ class CommandInvokerBranchTest extends AnyFunSuite with Matchers:
       invoker.execute(newCmd)
       invoker.history.size shouldBe 3
       invoker.canRedo shouldBe false
-
-  test("CommandInvoker.execute() with no redo history (while condition false)"):
-    val invoker = new CommandInvoker()
-    val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
-    invoker.execute(cmd1)
-    invoker.execute(cmd2)
-    invoker.canRedo shouldBe false
-    val cmd3 = createMoveCommand(sq(File.D, Rank.R2), sq(File.D, Rank.R4))
-    invoker.execute(cmd3)
-    invoker.history.size shouldBe 3
+    }

modules/core/src/test/scala/de/nowchess/chess/command/CommandInvokerTest.scala

@@ -17,63 +17,31 @@ class CommandInvokerTest extends AnyFunSuite with Matchers:
       previousContext = Some(GameContext.initial)
     )
 
-  test("CommandInvoker executes a command and adds it to history"):
+  test("execute appends commands and updates index"):
     val invoker = new CommandInvoker()
     val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
     invoker.execute(cmd) shouldBe true
     invoker.history.size shouldBe 1
     invoker.getCurrentIndex shouldBe 0
 
-  test("CommandInvoker executes multiple commands in sequence"):
-    val invoker = new CommandInvoker()
-    val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
     val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
-    invoker.execute(cmd1) shouldBe true
     invoker.execute(cmd2) shouldBe true
     invoker.history.size shouldBe 2
     invoker.getCurrentIndex shouldBe 1
 
-  test("CommandInvoker.canUndo returns false when empty"):
-    val invoker = new CommandInvoker()
-    invoker.canUndo shouldBe false
-
-  test("CommandInvoker.canUndo returns true after execution"):
+  test("undo and redo update index and availability flags"):
     val invoker = new CommandInvoker()
     val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
+    invoker.canUndo shouldBe false
     invoker.execute(cmd)
     invoker.canUndo shouldBe true
-
-  test("CommandInvoker.undo decrements current index"):
-    val invoker = new CommandInvoker()
-    val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    invoker.execute(cmd)
-    invoker.getCurrentIndex shouldBe 0
     invoker.undo() shouldBe true
     invoker.getCurrentIndex shouldBe -1
-
-  test("CommandInvoker.canRedo returns true after undo"):
-    val invoker = new CommandInvoker()
-    val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    invoker.execute(cmd)
-    invoker.undo()
     invoker.canRedo shouldBe true
-
-  test("CommandInvoker.redo re-executes a command"):
-    val invoker = new CommandInvoker()
-    val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    invoker.execute(cmd)
-    invoker.undo() shouldBe true
     invoker.redo() shouldBe true
     invoker.getCurrentIndex shouldBe 0
 
-  test("CommandInvoker.canUndo returns false when at beginning"):
-    val invoker = new CommandInvoker()
-    val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    invoker.execute(cmd)
-    invoker.undo()
-    invoker.canUndo shouldBe false
-
-  test("CommandInvoker clear removes all history"):
+  test("clear removes full history and resets index"):
     val invoker = new CommandInvoker()
     val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
     invoker.execute(cmd)
@@ -81,24 +49,7 @@ class CommandInvokerTest extends AnyFunSuite with Matchers:
     invoker.history.size shouldBe 0
     invoker.getCurrentIndex shouldBe -1
 
-  test("CommandInvoker discards all history when executing after undoing all"):
-    val invoker = new CommandInvoker()
-    val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
-    val cmd3 = createMoveCommand(sq(File.D, Rank.R2), sq(File.D, Rank.R4))
-    invoker.execute(cmd1)
-    invoker.execute(cmd2)
-    invoker.undo()
-    invoker.undo()
-    invoker.getCurrentIndex shouldBe -1
-    invoker.canRedo shouldBe true
-    invoker.execute(cmd3)
-    invoker.canRedo shouldBe false
-    invoker.history.size shouldBe 1
-    invoker.history(0) shouldBe cmd3
-    invoker.getCurrentIndex shouldBe 0
-
-  test("CommandInvoker discards redo history when executing mid-history"):
+  test("execute after undo discards redo history"):
     val invoker = new CommandInvoker()
     val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
     val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
@@ -111,6 +62,6 @@ class CommandInvokerTest extends AnyFunSuite with Matchers:
     invoker.execute(cmd3)
     invoker.canRedo shouldBe false
     invoker.history.size shouldBe 2
-    invoker.history(0) shouldBe cmd1
+    invoker.history.head shouldBe cmd1
     invoker.history(1) shouldBe cmd3
     invoker.getCurrentIndex shouldBe 1

modules/core/src/test/scala/de/nowchess/chess/command/CommandTest.scala

@@ -6,37 +6,19 @@ import org.scalatest.matchers.should.Matchers
 
 class CommandTest extends AnyFunSuite with Matchers:
 
-  test("QuitCommand can be created"):
+  test("QuitCommand properties and behavior"):
     val cmd = QuitCommand()
     cmd shouldNot be(null)
-
-  test("QuitCommand execute returns true"):
-    val cmd = QuitCommand()
     cmd.execute() shouldBe true
-
-  test("QuitCommand undo returns false (cannot undo quit)"):
-    val cmd = QuitCommand()
     cmd.undo() shouldBe false
-
-  test("QuitCommand description"):
-    val cmd = QuitCommand()
     cmd.description shouldBe "Quit game"
 
-  test("ResetCommand with no prior state"):
-    val cmd = ResetCommand()
-    cmd.execute() shouldBe true
-    cmd.undo() shouldBe false
+  test("ResetCommand behavior depends on previousContext"):
+    val noState = ResetCommand()
+    noState.execute() shouldBe true
+    noState.undo() shouldBe false
+    noState.description shouldBe "Reset board"
 
-  test("ResetCommand with prior state can undo"):
-    val cmd = ResetCommand(previousContext = Some(GameContext.initial))
-    cmd.execute() shouldBe true
-    cmd.undo() shouldBe true
-
-  test("ResetCommand with no context cannot undo"):
-    val cmd = ResetCommand(previousContext = None)
-    cmd.execute() shouldBe true
-    cmd.undo() shouldBe false
-
-  test("ResetCommand description"):
-    val cmd = ResetCommand()
-    cmd.description shouldBe "Reset board"
+    val withState = ResetCommand(previousContext = Some(GameContext.initial))
+    withState.execute() shouldBe true
+    withState.undo() shouldBe true

modules/core/src/test/scala/de/nowchess/chess/command/MoveCommandTest.scala

@@ -9,51 +9,31 @@ class MoveCommandTest extends AnyFunSuite with Matchers:
 
   private def sq(f: File, r: Rank): Square = Square(f, r)
 
-  test("MoveCommand with no moveResult defaults to None"):
+  test("MoveCommand defaults to empty optional state and false execute/undo"):
     val cmd = MoveCommand(from = sq(File.E, Rank.R2), to = sq(File.E, Rank.R4))
     cmd.moveResult shouldBe None
-    cmd.execute() shouldBe false
-
-  test("MoveCommand with no previousContext defaults to None"):
-    val cmd = MoveCommand(from = sq(File.E, Rank.R2), to = sq(File.E, Rank.R4))
     cmd.previousContext shouldBe None
+    cmd.execute() shouldBe false
     cmd.undo() shouldBe false
-
-  test("MoveCommand description is always returned"):
-    val cmd = MoveCommand(from = sq(File.E, Rank.R2), to = sq(File.E, Rank.R4))
     cmd.description shouldBe "Move from e2 to e4"
 
-  test("MoveCommand execute returns false when moveResult is None"):
-    val cmd = MoveCommand(from = sq(File.A, Rank.R1), to = sq(File.B, Rank.R3))
-    cmd.execute() shouldBe false
-
-  test("MoveCommand undo returns false when previousContext is None"):
-    val cmd = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4),
-      moveResult = Some(MoveResult.Successful(GameContext.initial, None)),
-      previousContext = None
-    )
-    cmd.undo() shouldBe false
-
-  test("MoveCommand execute returns true when moveResult is defined"):
-    val cmd = MoveCommand(
+  test("MoveCommand execute/undo succeed when state is present"):
+    val executable = MoveCommand(
       from = sq(File.E, Rank.R2),
       to = sq(File.E, Rank.R4),
       moveResult = Some(MoveResult.Successful(GameContext.initial, None))
     )
-    cmd.execute() shouldBe true
+    executable.execute() shouldBe true
 
-  test("MoveCommand undo returns true when previousContext is defined"):
-    val cmd = MoveCommand(
+    val undoable = MoveCommand(
       from = sq(File.E, Rank.R2),
       to = sq(File.E, Rank.R4),
       moveResult = Some(MoveResult.Successful(GameContext.initial, None)),
       previousContext = Some(GameContext.initial)
     )
-    cmd.undo() shouldBe true
+    undoable.undo() shouldBe true
 
-  test("MoveCommand should be immutable - fields cannot be mutated after creation"):
+  test("MoveCommand is immutable and preserves equality/hash semantics"):
     val cmd1 = MoveCommand(from = sq(File.E, Rank.R2), to = sq(File.E, Rank.R4))
 
     val result = MoveResult.Successful(GameContext.initial, None)
@@ -68,24 +48,23 @@ class MoveCommandTest extends AnyFunSuite with Matchers:
     cmd2.moveResult shouldBe Some(result)
     cmd2.previousContext shouldBe Some(GameContext.initial)
 
-  test("MoveCommand equals and hashCode respect immutability"):
-    val cmd1 = MoveCommand(
+    val eq1 = MoveCommand(
       from = sq(File.E, Rank.R2),
       to = sq(File.E, Rank.R4),
       moveResult = None,
       previousContext = None
     )
 
-    val cmd2 = MoveCommand(
+    val eq2 = MoveCommand(
       from = sq(File.E, Rank.R2),
       to = sq(File.E, Rank.R4),
       moveResult = None,
       previousContext = None
     )
 
-    cmd1 shouldBe cmd2
-    cmd1.hashCode shouldBe cmd2.hashCode
+    eq1 shouldBe eq2
+    eq1.hashCode shouldBe eq2.hashCode
 
-    val hash1 = cmd1.hashCode
-    val hash2 = cmd1.hashCode
+    val hash1 = eq1.hashCode
+    val hash2 = eq1.hashCode
     hash1 shouldBe hash2

modules/core/src/test/scala/de/nowchess/chess/engine/GameEngineCoverageRegressionTest.scala

@@ -17,7 +17,7 @@ class GameEngineCoverageRegressionTest extends AnyFunSuite with Matchers:
 
   private def captureEvents(engine: GameEngine): collection.mutable.ListBuffer[GameEvent] =
     val events = collection.mutable.ListBuffer[GameEvent]()
-    engine.subscribe(new Observer { def onGameEvent(event: GameEvent): Unit = events += event })
+    engine.subscribe((event: GameEvent) => events += event)
     events
 
   test("accessors expose redo availability and command history"):
@@ -141,6 +141,15 @@ class GameEngineCoverageRegressionTest extends AnyFunSuite with Matchers:
     engine.replayMoves(List(normalMove), engine.context) shouldBe Right(())
     engine.context.moves.lastOption shouldBe Some(normalMove)
 
+  test("replayMoves skips later moves after the first move triggers an error"):
+    val engine = new GameEngine()
+    val saved = engine.context
+    val illegalPromotion = Move(sq("e2"), sq("e1"), MoveType.Promotion(PromotionPiece.Queen))
+    val trailingMove = Move(sq("e2"), sq("e4"))
+
+    engine.replayMoves(List(illegalPromotion, trailingMove), saved) shouldBe Left("Promotion required for move e2e1")
+    engine.context shouldBe saved
+
 
   test("normalMoveNotation handles missing source piece"):
     val engine = new GameEngine()

modules/core/src/test/scala/de/nowchess/chess/engine/GameEngineScenarioTest.scala

@@ -12,47 +12,31 @@ class GameEngineScenarioTest extends AnyFunSuite with Matchers:
 
   // ── Observer wiring ────────────────────────────────────────────
 
-  test("subscribe adds observer to notification list"):
+  test("observer subscribe and unsubscribe behavior"):
     val engine = EngineTestHelpers.makeEngine()
     val observer = new EngineTestHelpers.MockObserver()
     engine.subscribe(observer)
     engine.processUserInput("e2e4")
     observer.hasEvent[MoveExecutedEvent] shouldBe true
-
-  test("unsubscribe removes observer from notification list"):
-    val engine = EngineTestHelpers.makeEngine()
-    val observer = new EngineTestHelpers.MockObserver()
+    val countBeforeUnsubscribe = observer.eventCount
     engine.subscribe(observer)
     engine.unsubscribe(observer)
     engine.processUserInput("e2e4")
-    observer.eventCount shouldBe 0
+    observer.eventCount shouldBe countBeforeUnsubscribe
 
   // ── Initial state ──────────────────────────────────────────────
 
-  test("initial game context has standard starting position"):
+  test("initial engine state is standard"):
     val engine = EngineTestHelpers.makeEngine()
     engine.board.pieceAt(Square(File.E, Rank.R1)) shouldBe Some(Piece.WhiteKing)
-
-  test("initial turn is white"):
-    val engine = EngineTestHelpers.makeEngine()
     engine.turn shouldBe Color.White
 
   // ── Quit command ──────────────────────────────────────────────
 
-  test("quit command does not error"):
+  test("quit aliases and reset keep engine responsive"):
     val engine = EngineTestHelpers.makeEngine()
     engine.processUserInput("quit")
-    // Quit just returns, no event
-
-  test("q alias for quit works"):
-    val engine = EngineTestHelpers.makeEngine()
     engine.processUserInput("q")
-    // Quit just returns, no event
-
-  // ── Reset command ──────────────────────────────────────────────
-
-  test("reset command returns game to initial position"):
-    val engine = EngineTestHelpers.makeEngine()
     engine.processUserInput("e2e4")
 
     engine.reset()
@@ -62,20 +46,16 @@ class GameEngineScenarioTest extends AnyFunSuite with Matchers:
 
   // ── Turn toggling ──────────────────────────────────────────────
 
-  test("turn toggles to black after valid white move"):
+  test("turn toggles across valid move sequence"):
     val engine = EngineTestHelpers.makeEngine()
     engine.processUserInput("e2e4")
     engine.turn shouldBe Color.Black
-
-  test("turn toggles back to white after black move"):
-    val engine = EngineTestHelpers.makeEngine()
-    engine.processUserInput("e2e4")
     engine.processUserInput("e7e5")
     engine.turn shouldBe Color.White
 
   // ── Invalid moves (minimal) ────────────────────────────────────
 
-  test("move with no piece at source fails"):
+  test("invalid move forms trigger InvalidMoveEvent and keep turn where relevant"):
     val engine = EngineTestHelpers.makeEngine()
     val observer = new EngineTestHelpers.MockObserver()
     engine.subscribe(observer)
@@ -85,20 +65,10 @@ class GameEngineScenarioTest extends AnyFunSuite with Matchers:
     observer.hasEvent[InvalidMoveEvent] shouldBe true
     engine.turn shouldBe Color.White  // turn unchanged
 
-  test("move with opponent piece fails"):
-    val engine = EngineTestHelpers.makeEngine()
-    val observer = new EngineTestHelpers.MockObserver()
-    engine.subscribe(observer)
-
     engine.processUserInput("e7e5")  // try to move black pawn on white's turn
 
     observer.hasEvent[InvalidMoveEvent] shouldBe true
 
-  test("illegal move fails (pawn backward)"):
-    val engine = EngineTestHelpers.makeEngine()
-    val observer = new EngineTestHelpers.MockObserver()
-    engine.subscribe(observer)
-
     engine.processUserInput("e2e4")
     engine.processUserInput("e5e4")  // pawn backward
 
@@ -106,8 +76,15 @@ class GameEngineScenarioTest extends AnyFunSuite with Matchers:
 
   // ── Undo/Redo ────────────────────────────────────────────────
 
-  test("undo restores previous position"):
+  test("undo redo success and empty-history failures"):
     val engine = EngineTestHelpers.makeEngine()
+    val observer = new EngineTestHelpers.MockObserver()
+    engine.subscribe(observer)
+
+    engine.undo()
+    observer.hasEvent[InvalidMoveEvent] shouldBe true
+    observer.clear()
+
     engine.processUserInput("e2e4")
 
     engine.undo()
@@ -115,37 +92,17 @@ class GameEngineScenarioTest extends AnyFunSuite with Matchers:
     engine.board.pieceAt(Square(File.E, Rank.R2)) shouldBe Some(Piece.WhitePawn)
     engine.turn shouldBe Color.White
 
-  test("redo replays last undone move"):
-    val engine = EngineTestHelpers.makeEngine()
-    engine.processUserInput("e2e4")
-    engine.undo()
-
     engine.redo()
 
     engine.board.pieceAt(Square(File.E, Rank.R4)) shouldBe Some(Piece.WhitePawn)
     engine.turn shouldBe Color.Black
-
-  test("undo on empty history triggers InvalidMoveEvent"):
-    val engine = EngineTestHelpers.makeEngine()
-    val observer = new EngineTestHelpers.MockObserver()
-    engine.subscribe(observer)
-
-    engine.undo()
-
-    observer.hasEvent[InvalidMoveEvent] shouldBe true
-
-  test("redo on empty future history triggers InvalidMoveEvent"):
-    val engine = EngineTestHelpers.makeEngine()
-    val observer = new EngineTestHelpers.MockObserver()
-    engine.subscribe(observer)
-
+    observer.clear()
     engine.redo()
-
     observer.hasEvent[InvalidMoveEvent] shouldBe true
 
   // ── Fifty-move rule ────────────────────────────────────────────
 
-  test("FiftyMoveRuleAvailableEvent fired when half-move clock reaches 100"):
+  test("fifty-move event and draw claim success/failure"):
     val engine = EngineTestHelpers.makeEngine()
     val observer = new EngineTestHelpers.MockObserver()
     engine.subscribe(observer)
@@ -159,13 +116,6 @@ class GameEngineScenarioTest extends AnyFunSuite with Matchers:
 
     observer.hasEvent[FiftyMoveRuleAvailableEvent] shouldBe true
 
-  // ── Draw claiming ──────────────────────────────────────────────
-
-  test("draw claim succeeds when available"):
-    val engine = EngineTestHelpers.makeEngine()
-    val observer = new EngineTestHelpers.MockObserver()
-    engine.subscribe(observer)
-
     // Load position with sufficient move history for draw claim
     EngineTestHelpers.loadFen(engine, "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 100 1")
     observer.clear()
@@ -174,12 +124,9 @@ class GameEngineScenarioTest extends AnyFunSuite with Matchers:
 
     observer.hasEvent[DrawClaimedEvent] shouldBe true
 
-  test("draw claim fails when not available"):
-    val engine = EngineTestHelpers.makeEngine()
-    val observer = new EngineTestHelpers.MockObserver()
-    engine.subscribe(observer)
-
     // Initial position has no draw available
+    observer.clear()
+    engine.reset()
     engine.processUserInput("draw")
 
     observer.hasEvent[InvalidMoveEvent] shouldBe true

modules/io/src/test/scala/de/nowchess/io/fen/FenExporterTest.scala

@@ -29,11 +29,10 @@ class FenExporterTest extends AnyFunSuite with Matchers:
       moves = List.fill(moveCount)(dummyMove)
     )
 
-  test("export initial position to FEN"):
-    val fen = FenExporter.gameContextToFen(GameContext.initial)
-    fen shouldBe "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
+  test("exportGameContextToFen handles initial and typical developed position"):
+    FenExporter.gameContextToFen(GameContext.initial) shouldBe
+      "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
 
-  test("export position after e4"):
     val gameContext = context(
       piecePlacement = "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR",
       turn = Color.Black,
@@ -42,11 +41,11 @@ class FenExporterTest extends AnyFunSuite with Matchers:
       halfMoveClock = 0,
       moveCount = 0
     )
-    val fen = FenExporter.gameContextToFen(gameContext)
-    fen shouldBe "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1"
+    FenExporter.gameContextToFen(gameContext) shouldBe
+      "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1"
 
-  test("export position with no castling"):
-    val gameContext = context(
+  test("export handles castling rights variants and en-passant with counters"):
+    val noCastling = context(
       piecePlacement = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR",
       turn = Color.White,
       castlingRights = CastlingRights.None,
@@ -54,11 +53,10 @@ class FenExporterTest extends AnyFunSuite with Matchers:
       halfMoveClock = 0,
       moveCount = 0
     )
-    val fen = FenExporter.gameContextToFen(gameContext)
-    fen shouldBe "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1"
+    FenExporter.gameContextToFen(noCastling) shouldBe
+      "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1"
 
-  test("export position with partial castling"):
-    val gameContext = context(
+    val partialCastling = context(
       piecePlacement = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR",
       turn = Color.White,
       castlingRights = CastlingRights(
@@ -71,11 +69,10 @@ class FenExporterTest extends AnyFunSuite with Matchers:
       halfMoveClock = 5,
       moveCount = 4
     )
-    val fen = FenExporter.gameContextToFen(gameContext)
-    fen shouldBe "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w Kq - 5 3"
+    FenExporter.gameContextToFen(partialCastling) shouldBe
+      "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w Kq - 5 3"
 
-  test("export position with en passant and move counts"):
-    val gameContext = context(
+    val withEnPassant = context(
       piecePlacement = "rnbqkbnr/pp1ppppp/8/2pP4/8/8/PPPP1PPP/RNBQKBNR",
       turn = Color.White,
       castlingRights = CastlingRights.All,
@@ -83,8 +80,8 @@ class FenExporterTest extends AnyFunSuite with Matchers:
       halfMoveClock = 2,
       moveCount = 4
     )
-    val fen = FenExporter.gameContextToFen(gameContext)
-    fen shouldBe "rnbqkbnr/pp1ppppp/8/2pP4/8/8/PPPP1PPP/RNBQKBNR w KQkq c6 2 3"
+    FenExporter.gameContextToFen(withEnPassant) shouldBe
+      "rnbqkbnr/pp1ppppp/8/2pP4/8/8/PPPP1PPP/RNBQKBNR w KQkq c6 2 3"
 
   test("halfMoveClock round-trips through FEN export and import"):
     val gameContext = GameContext(

modules/io/src/test/scala/de/nowchess/io/fen/FenParserTest.scala

@@ -6,71 +6,43 @@ import org.scalatest.matchers.should.Matchers
 
 class FenParserTest extends AnyFunSuite with Matchers:
 
-  test("parseBoard: initial position places pieces correctly"):
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR"
-    val board = FenParser.parseBoard(fen)
-    board.map(_.pieceAt(Square(File.E, Rank.R2))) shouldBe Some(Some(Piece.WhitePawn))
-    board.map(_.pieceAt(Square(File.E, Rank.R8))) shouldBe Some(Some(Piece.BlackKing))
+  test("parseBoard parses canonical positions and supports round-trip"):
+    val initial = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR"
+    val empty = "8/8/8/8/8/8/8/8"
+    val partial = "8/8/4k3/8/4K3/8/8/8"
 
-  test("parseBoard: empty board"):
-    val fen = "8/8/8/8/8/8/8/8"
-    val board = FenParser.parseBoard(fen)
-    board.get.pieces.size shouldBe 0
+    FenParser.parseBoard(initial).map(_.pieceAt(Square(File.E, Rank.R2))) shouldBe Some(Some(Piece.WhitePawn))
+    FenParser.parseBoard(initial).map(_.pieceAt(Square(File.E, Rank.R8))) shouldBe Some(Some(Piece.BlackKing))
+    FenParser.parseBoard(empty).map(_.pieces.size) shouldBe Some(0)
+    FenParser.parseBoard(partial).map(_.pieceAt(Square(File.E, Rank.R6))) shouldBe Some(Some(Piece.BlackKing))
 
-  test("parseBoard: partial position"):
-    val fen = "8/8/4k3/8/4K3/8/8/8"
-    val board = FenParser.parseBoard(fen)
-    board.map(_.pieceAt(Square(File.E, Rank.R6))) shouldBe Some(Some(Piece.BlackKing))
+    FenParser.parseBoard(initial).map(FenExporter.boardToFen) shouldBe Some(initial)
+    FenParser.parseBoard(empty).map(FenExporter.boardToFen) shouldBe Some(empty)
 
-  test("round-trip initial position"):
-    val originalFen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR"
-    val exported = FenParser.parseBoard(originalFen).map(FenExporter.boardToFen)
-    exported shouldBe Some(originalFen)
-
-  test("round-trip empty board"):
-    val originalFen = "8/8/8/8/8/8/8/8"
-    val exported = FenParser.parseBoard(originalFen).map(FenExporter.boardToFen)
-    exported shouldBe Some(originalFen)
-
-  test("parseFen: initial position with all fields"):
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
-    val context = FenParser.parseFen(fen)
-    context.fold(_ => fail(), ctx =>
+  test("parseFen parses full state for common valid inputs"):
+    FenParser.parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1").fold(_ => fail(), ctx =>
       ctx.turn shouldBe Color.White
       ctx.castlingRights.whiteKingSide shouldBe true
       ctx.enPassantSquare shouldBe None
       ctx.halfMoveClock shouldBe 0
     )
 
-  test("parseFen: position after e4"):
-    val fen = "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1"
-    val context = FenParser.parseFen(fen)
-    context.fold(_ => fail(), ctx =>
+    FenParser.parseFen("rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1").fold(_ => fail(), ctx =>
       ctx.turn shouldBe Color.Black
       ctx.enPassantSquare shouldBe Some(Square(File.E, Rank.R3))
     )
 
-  test("parseFen: no castling rights"):
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1"
-    val context = FenParser.parseFen(fen)
-    context.fold(_ => fail(), ctx =>
+    FenParser.parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1").fold(_ => fail(), ctx =>
       ctx.castlingRights.whiteKingSide shouldBe false
       ctx.castlingRights.blackQueenSide shouldBe false
     )
 
-  test("parseFen: invalid color fails"):
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR x KQkq - 0 1"
-    FenParser.parseFen(fen).isLeft shouldBe true
+  test("parseFen rejects invalid color and castling tokens"):
+    FenParser.parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR x KQkq - 0 1").isLeft shouldBe true
+    FenParser.parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w XYZ - 0 1").isLeft shouldBe true
 
-  test("parseFen: invalid castling fails"):
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w XYZ - 0 1"
-    FenParser.parseFen(fen).isLeft shouldBe true
-
-  test("importGameContext: valid FEN"):
+  test("importGameContext returns Right for valid and Left for invalid FEN"):
     val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
     FenParser.importGameContext(fen).isRight shouldBe true
-
-  test("importGameContext: invalid FEN"):
-    val invalidFen = "invalid fen string"
-    FenParser.importGameContext(invalidFen).isLeft shouldBe true
+    FenParser.importGameContext("invalid fen string").isLeft shouldBe true
 

modules/io/src/test/scala/de/nowchess/io/pgn/PgnExporterTest.scala

@@ -1,124 +1,65 @@
 package de.nowchess.io.pgn
 
-import de.nowchess.api.board.{PieceType, *}
-import de.nowchess.api.move.{PromotionPiece, Move, MoveType}
+import de.nowchess.api.board.*
 import de.nowchess.api.game.GameContext
+import de.nowchess.api.move.{Move, MoveType, PromotionPiece}
 import org.scalatest.funsuite.AnyFunSuite
 import org.scalatest.matchers.should.Matchers
 
 class PgnExporterTest extends AnyFunSuite with Matchers:
 
-  test("export empty game") {
+  test("exportGame renders headers and basic move text"):
     val headers = Map("Event" -> "Test", "White" -> "A", "Black" -> "B")
-    val pgn = PgnExporter.exportGame(headers, List.empty)
+    val emptyPgn = PgnExporter.exportGame(headers, List.empty)
+    emptyPgn.contains("[Event \"Test\"]") shouldBe true
+    emptyPgn.contains("[White \"A\"]") shouldBe true
+    emptyPgn.contains("[Black \"B\"]") shouldBe true
 
-    pgn.contains("[Event \"Test\"]") shouldBe true
-    pgn.contains("[White \"A\"]") shouldBe true
-    pgn.contains("[Black \"B\"]") shouldBe true
-  }
+    val moves = List(Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal()))
+    PgnExporter.exportGame(headers, moves).contains("1. e4") shouldBe true
 
-  test("export single move") {
-    val headers = Map("Event" -> "Test", "White" -> "A", "Black" -> "B")
-    val moves = List(Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal(false)))
-    val pgn = PgnExporter.exportGame(headers, moves)
+  test("exportGame renders castling grouping and result markers"):
+    PgnExporter.exportGame(Map("Event" -> "Test"), List(Move(Square(File.E, Rank.R1), Square(File.G, Rank.R1), MoveType.CastleKingside))) should include("O-O")
+    PgnExporter.exportGame(Map("Event" -> "Test"), List(Move(Square(File.E, Rank.R1), Square(File.C, Rank.R1), MoveType.CastleQueenside))) should include("O-O-O")
 
-    pgn.contains("1. e4") shouldBe true
-  }
-
-  test("export castling") {
-    val headers = Map("Event" -> "Test")
-    val moves = List(Move(Square(File.E, Rank.R1), Square(File.G, Rank.R1), MoveType.CastleKingside))
-    val pgn = PgnExporter.exportGame(headers, moves)
-
-    pgn.contains("O-O") shouldBe true
-  }
-
-  test("export game sequence") {
-    val headers = Map("Event" -> "Test", "White" -> "A", "Black" -> "B", "Result" -> "1-0")
-    val moves = List(
-      Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal(false)),
-      Move(Square(File.C, Rank.R7), Square(File.C, Rank.R5), MoveType.Normal(false)),
-      Move(Square(File.G, Rank.R1), Square(File.F, Rank.R3), MoveType.Normal(false))
+    val seq = List(
+      Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal()),
+      Move(Square(File.C, Rank.R7), Square(File.C, Rank.R5), MoveType.Normal()),
+      Move(Square(File.G, Rank.R1), Square(File.F, Rank.R3), MoveType.Normal())
     )
-    val pgn = PgnExporter.exportGame(headers, moves)
+    val grouped = PgnExporter.exportGame(Map("Result" -> "1-0"), seq)
+    grouped should include("1. e4 c5")
+    grouped should include("2. Nf3")
 
-    pgn.contains("1. e4 c5") shouldBe true
-    pgn.contains("2. Nf3") shouldBe true
+    val oneMove = List(Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal()))
+    PgnExporter.exportGame(Map.empty, oneMove) shouldBe "1. e4 *"
+    PgnExporter.exportGame(Map("Result" -> "1/2-1/2"), oneMove) should endWith("1/2-1/2")
+
+  test("exportGame handles promotion suffixes and normal move formatting"):
+    List(
+      PromotionPiece.Queen -> "=Q",
+      PromotionPiece.Rook -> "=R",
+      PromotionPiece.Bishop -> "=B",
+      PromotionPiece.Knight -> "=N"
+    ).foreach { (piece, suffix) =>
+      val move = Move(Square(File.E, Rank.R7), Square(File.E, Rank.R8), MoveType.Promotion(piece))
+      PgnExporter.exportGame(Map.empty, List(move)) should include(s"e8$suffix")
     }
 
-  test("export game with no headers returns only move text") {
-    val moves = List(Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal(false)))
-    val pgn = PgnExporter.exportGame(Map.empty, moves)
+    val normal = PgnExporter.exportGame(Map.empty, List(Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal())))
+    normal should include("e4")
+    normal should not include "="
 
-    pgn shouldBe "1. e4 *"
-  }
-
-  test("export queenside castling") {
-    val headers = Map("Event" -> "Test")
-    val moves = List(Move(Square(File.E, Rank.R1), Square(File.C, Rank.R1), MoveType.CastleQueenside))
-    val pgn = PgnExporter.exportGame(headers, moves)
-
-    pgn.contains("O-O-O") shouldBe true
-  }
-
-  test("exportGame encodes promotion to Queen as =Q suffix") {
-    val moves = List(Move(Square(File.E, Rank.R7), Square(File.E, Rank.R8), MoveType.Promotion(PromotionPiece.Queen)))
-    val pgn = PgnExporter.exportGame(Map.empty, moves)
-    pgn should include ("e8=Q")
-  }
-
-  test("exportGame encodes promotion to Rook as =R suffix") {
-    val moves = List(Move(Square(File.E, Rank.R7), Square(File.E, Rank.R8), MoveType.Promotion(PromotionPiece.Rook)))
-    val pgn = PgnExporter.exportGame(Map.empty, moves)
-    pgn should include ("e8=R")
-  }
-
-  test("exportGame encodes promotion to Bishop as =B suffix") {
-    val moves = List(Move(Square(File.E, Rank.R7), Square(File.E, Rank.R8), MoveType.Promotion(PromotionPiece.Bishop)))
-    val pgn = PgnExporter.exportGame(Map.empty, moves)
-    pgn should include ("e8=B")
-  }
-
-  test("exportGame encodes promotion to Knight as =N suffix") {
-    val moves = List(Move(Square(File.E, Rank.R7), Square(File.E, Rank.R8), MoveType.Promotion(PromotionPiece.Knight)))
-    val pgn = PgnExporter.exportGame(Map.empty, moves)
-    pgn should include ("e8=N")
-  }
-
-  test("exportGame does not add suffix for normal moves") {
-    val moves = List(Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal(false)))
-    val pgn = PgnExporter.exportGame(Map.empty, moves)
-    pgn should include ("e4")
-    pgn should not include "="
-  }
-
-  test("exportGame uses Result header as termination marker"):
-    val moves = List(Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal(false)))
-    val pgn = PgnExporter.exportGame(Map("Result" -> "1/2-1/2"), moves)
-    pgn should endWith("1/2-1/2")
-
-  test("exportGame with no Result header still uses * as default"):
-    val moves = List(Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal(false)))
-    val pgn = PgnExporter.exportGame(Map.empty, moves)
-    pgn shouldBe "1. e4 *"
-
-  test("exportGameContext: moves are preserved in output") {
+  test("exportGameContext preserves moves and default headers"):
     val moves = List(
-      Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal(false)),
-      Move(Square(File.E, Rank.R7), Square(File.E, Rank.R5), MoveType.Normal(false))
+      Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal()),
+      Move(Square(File.E, Rank.R7), Square(File.E, Rank.R5), MoveType.Normal())
     )
-    val ctx = GameContext.initial.copy(moves = moves)
-    val exported = PgnExporter.exportGameContext(ctx)
+    val withMoves = PgnExporter.exportGameContext(GameContext.initial.copy(moves = moves))
+    withMoves.contains("e4") shouldBe true
+    withMoves.contains("e5") shouldBe true
 
-    exported.contains("e4") shouldBe true
-    exported.contains("e5") shouldBe true
-  }
-
-  test("exportGameContext: empty game returns headers only") {
-    val ctx = GameContext.initial
-    val exported = PgnExporter.exportGameContext(ctx)
-
-    exported.contains("[Event") shouldBe true
-    exported.contains("*") shouldBe true  // Result terminator
-  }
+    val empty = PgnExporter.exportGameContext(GameContext.initial)
+    empty.contains("[Event") shouldBe true
+    empty.contains("*") shouldBe true
 

modules/io/src/test/scala/de/nowchess/io/pgn/PgnParserTest.scala

@@ -9,186 +9,106 @@ import org.scalatest.matchers.should.Matchers
 
 class PgnParserTest extends AnyFunSuite with Matchers:
 
-  test("parse PGN headers only"):
-    val pgn = """[Event "Test Game"]
+  test("parsePgn handles headers standard sequences captures castling and skipped tokens"):
+    val headerOnly = """[Event "Test Game"]
 [White "Alice"]
 [Black "Bob"]
 [Result "1-0"]"""
-    val game = PgnParser.parsePgn(pgn)
-    game.isDefined shouldBe true
-    game.get.headers("Event") shouldBe "Test Game"
-    game.get.headers("White") shouldBe "Alice"
+    val onlyHeaders = PgnParser.parsePgn(headerOnly)
+    onlyHeaders.isDefined shouldBe true
+    onlyHeaders.get.headers("Event") shouldBe "Test Game"
+    onlyHeaders.get.headers("White") shouldBe "Alice"
 
-  test("parse simple game sequence"):
-    val pgn = """[Event "Test"]
+    val simple = PgnParser.parsePgn("""[Event "Test"]
 
-1. e4 e5 2. Nf3 Nc6"""
-    val game = PgnParser.parsePgn(pgn)
-    game.isDefined shouldBe true
-    game.get.moves.length shouldBe 4
+1. e4 e5 2. Nf3 Nc6""")
+    simple.map(_.moves.length) shouldBe Some(4)
 
-  test("parse move with capture"):
-    val pgn = """[Event "Test"]
+    val capture = PgnParser.parsePgn("""[Event "Test"]
 
-1. Nf3 e5 2. Nxe5"""
-    val game = PgnParser.parsePgn(pgn)
-    game.isDefined shouldBe true
-    game.get.moves.length shouldBe 3
-    game.get.moves(2).to shouldBe Square(File.E, Rank.R5)
+1. Nf3 e5 2. Nxe5""")
+    capture.map(_.moves.length) shouldBe Some(3)
+    capture.get.moves(2).to shouldBe Square(File.E, Rank.R5)
 
-  test("parse kingside castling O-O"):
-    val pgn = """[Event "Test"]
+    val whiteKs = PgnParser.parsePgn("""[Event "Test"]
 
-1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. O-O"""
-    val game = PgnParser.parsePgn(pgn)
-    game.isDefined shouldBe true
-    val lastMove = game.get.moves.last
-    lastMove.moveType shouldBe MoveType.CastleKingside
-    lastMove.from shouldBe Square(File.E, Rank.R1)
-    lastMove.to shouldBe Square(File.G, Rank.R1)
+1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. O-O""").get.moves.last
+    whiteKs.moveType shouldBe MoveType.CastleKingside
+    whiteKs.from shouldBe Square(File.E, Rank.R1)
+    whiteKs.to shouldBe Square(File.G, Rank.R1)
 
-  test("parse queenside castling O-O-O"):
-    val pgn = """[Event "Test"]
+    val whiteQs = PgnParser.parsePgn("""[Event "Test"]
 
-1. d4 d5 2. Nc3 Nc6 3. Bf4 Bf5 4. Qd2 Qd7 5. O-O-O"""
-    val game = PgnParser.parsePgn(pgn)
-    game.isDefined shouldBe true
-    val lastMove = game.get.moves.last
-    lastMove.moveType shouldBe MoveType.CastleQueenside
-    lastMove.from shouldBe Square(File.E, Rank.R1)
-    lastMove.to shouldBe Square(File.C, Rank.R1)
+1. d4 d5 2. Nc3 Nc6 3. Bf4 Bf5 4. Qd2 Qd7 5. O-O-O""").get.moves.last
+    whiteQs.moveType shouldBe MoveType.CastleQueenside
+    whiteQs.from shouldBe Square(File.E, Rank.R1)
+    whiteQs.to shouldBe Square(File.C, Rank.R1)
 
-  test("parse black kingside castling"):
-    val pgn = """[Event "Test"]
+    val blackKs = PgnParser.parsePgn("""[Event "Test"]
 
-1. e4 e5 2. Nf3 Nf6 3. Bc4 Be7 4. O-O O-O"""
-    val game = PgnParser.parsePgn(pgn)
-    game.isDefined shouldBe true
-    val blackCastle = game.get.moves.last
-    blackCastle.moveType shouldBe MoveType.CastleKingside
-    blackCastle.from shouldBe Square(File.E, Rank.R8)
+1. e4 e5 2. Nf3 Nf6 3. Bc4 Be7 4. O-O O-O""").get.moves.last
+    blackKs.moveType shouldBe MoveType.CastleKingside
+    blackKs.from shouldBe Square(File.E, Rank.R8)
 
-  test("parse black queenside castling"):
-    val pgn = """[Event "Test"]
+    val blackQs = PgnParser.parsePgn("""[Event "Test"]
 
-1. d4 d5 2. Nc3 Nc6 3. Bf4 Bf5 4. Qd2 Qd7 5. O-O-O O-O-O"""
-    val game = PgnParser.parsePgn(pgn)
-    game.isDefined shouldBe true
-    val lastMove = game.get.moves.last
-    lastMove.moveType shouldBe MoveType.CastleQueenside
-    lastMove.from shouldBe Square(File.E, Rank.R8)
-    lastMove.to shouldBe Square(File.C, Rank.R8)
+1. d4 d5 2. Nc3 Nc6 3. Bf4 Bf5 4. Qd2 Qd7 5. O-O-O O-O-O""").get.moves.last
+    blackQs.moveType shouldBe MoveType.CastleQueenside
+    blackQs.from shouldBe Square(File.E, Rank.R8)
+    blackQs.to shouldBe Square(File.C, Rank.R8)
 
-  test("result tokens are skipped"):
-    val pgn = """[Event "Test"]
+    PgnParser.parsePgn("""[Event "Test"]
 
-1. e4 e5 1-0"""
-    val game = PgnParser.parsePgn(pgn)
-    game.isDefined shouldBe true
-    game.get.moves.length shouldBe 2
+1. e4 e5 1-0""").map(_.moves.length) shouldBe Some(2)
+    PgnParser.parsePgn("""[Event "Test"]
 
-  test("unrecognised tokens are skipped"):
-    val pgn = """[Event "Test"]
+1. e4 INVALID e5""").map(_.moves.length) shouldBe Some(2)
 
-1. e4 INVALID e5"""
-    val game = PgnParser.parsePgn(pgn)
-    game.isDefined shouldBe true
-    game.get.moves.length shouldBe 2
-
-  test("parseAlgebraicMove: pawn to e4"):
+  test("parseAlgebraicMove resolves pawn knight king and disambiguation cases"):
     val board = Board.initial
-    val result = PgnParser.parseAlgebraicMove("e4", GameContext.initial.withBoard(board), Color.White)
-    result.isDefined shouldBe true
-    result.get.to shouldBe Square(File.E, Rank.R4)
+    PgnParser.parseAlgebraicMove("e4", GameContext.initial.withBoard(board), Color.White).get.to shouldBe Square(File.E, Rank.R4)
+    PgnParser.parseAlgebraicMove("Nf3", GameContext.initial.withBoard(board), Color.White).get.to shouldBe Square(File.F, Rank.R3)
 
-  test("parseAlgebraicMove: knight to f3"):
-    val board = Board.initial
-    val result = PgnParser.parseAlgebraicMove("Nf3", GameContext.initial.withBoard(board), Color.White)
-    result.isDefined shouldBe true
-    result.get.to shouldBe Square(File.F, Rank.R3)
-
-  test("parseAlgebraicMove: promotion to Queen"):
-    val board = FenParser.parseBoard("8/4P3/4k3/8/8/8/8/8").get
-    val result = PgnParser.parseAlgebraicMove("e7e8=Q", GameContext.initial.withBoard(board), Color.White)
-    result.isDefined shouldBe true
-    result.get.moveType shouldBe MoveType.Promotion(PromotionPiece.Queen)
-
-  test("parseAlgebraicMove: promotion to Rook"):
-    val board = FenParser.parseBoard("8/4P3/4k3/8/8/8/8/8").get
-    val result = PgnParser.parseAlgebraicMove("e7e8=R", GameContext.initial.withBoard(board), Color.White)
-    result.isDefined shouldBe true
-    result.get.moveType shouldBe MoveType.Promotion(PromotionPiece.Rook)
-
-  test("parseAlgebraicMove: promotion to Bishop"):
-    val board = FenParser.parseBoard("8/4P3/4k3/8/8/8/8/8").get
-    val result = PgnParser.parseAlgebraicMove("e7e8=B", GameContext.initial.withBoard(board), Color.White)
-    result.isDefined shouldBe true
-    result.get.moveType shouldBe MoveType.Promotion(PromotionPiece.Bishop)
-
-  test("parseAlgebraicMove: promotion to Knight"):
-    val board = FenParser.parseBoard("8/4P3/4k3/8/8/8/8/8").get
-    val result = PgnParser.parseAlgebraicMove("e7e8=N", GameContext.initial.withBoard(board), Color.White)
-    result.isDefined shouldBe true
-    result.get.moveType shouldBe MoveType.Promotion(PromotionPiece.Knight)
-
-  test("file disambiguation: Rad1"):
-    val pieces: Map[Square, Piece] = Map(
+    val rookPieces: Map[Square, Piece] = Map(
       Square(File.A, Rank.R1) -> Piece(Color.White, PieceType.Rook),
       Square(File.H, Rank.R1) -> Piece(Color.White, PieceType.Rook),
       Square(File.E, Rank.R1) -> Piece(Color.White, PieceType.King),
       Square(File.E, Rank.R8) -> Piece(Color.Black, PieceType.King)
     )
-    val board = Board(pieces)
-    val result = PgnParser.parseAlgebraicMove("Rad1", GameContext.initial.withBoard(board), Color.White)
-    result.isDefined shouldBe true
-    result.get.from shouldBe Square(File.A, Rank.R1)
-
-  test("rank disambiguation: R1a3"):
-    val pieces: Map[Square, Piece] = Map(
+    val rankPieces: Map[Square, Piece] = Map(
       Square(File.A, Rank.R1) -> Piece(Color.White, PieceType.Rook),
       Square(File.A, Rank.R4) -> Piece(Color.White, PieceType.Rook),
       Square(File.E, Rank.R1) -> Piece(Color.White, PieceType.King),
       Square(File.E, Rank.R8) -> Piece(Color.Black, PieceType.King)
     )
-    val board = Board(pieces)
-    val result = PgnParser.parseAlgebraicMove("R1a3", GameContext.initial.withBoard(board), Color.White)
-    result.isDefined shouldBe true
-    result.get.from shouldBe Square(File.A, Rank.R1)
+    PgnParser.parseAlgebraicMove("Rad1", GameContext.initial.withBoard(Board(rookPieces)), Color.White).get.from shouldBe Square(File.A, Rank.R1)
+    PgnParser.parseAlgebraicMove("R1a3", GameContext.initial.withBoard(Board(rankPieces)), Color.White).get.from shouldBe Square(File.A, Rank.R1)
 
-  test("importGameContext: valid PGN"):
+    val kingBoard = FenParser.parseBoard("4k3/8/8/8/8/8/8/4K3").get
+    val king = PgnParser.parseAlgebraicMove("Ke2", GameContext.initial.withBoard(kingBoard), Color.White)
+    king.isDefined shouldBe true
+    king.get.from shouldBe Square(File.E, Rank.R1)
+    king.get.to shouldBe Square(File.E, Rank.R2)
+
+  test("parseAlgebraicMove handles all promotion targets"):
+    val board = FenParser.parseBoard("8/4P3/4k3/8/8/8/8/8").get
+    PgnParser.parseAlgebraicMove("e7e8=Q", GameContext.initial.withBoard(board), Color.White).get.moveType shouldBe MoveType.Promotion(PromotionPiece.Queen)
+    PgnParser.parseAlgebraicMove("e7e8=R", GameContext.initial.withBoard(board), Color.White).get.moveType shouldBe MoveType.Promotion(PromotionPiece.Rook)
+    PgnParser.parseAlgebraicMove("e7e8=B", GameContext.initial.withBoard(board), Color.White).get.moveType shouldBe MoveType.Promotion(PromotionPiece.Bishop)
+    PgnParser.parseAlgebraicMove("e7e8=N", GameContext.initial.withBoard(board), Color.White).get.moveType shouldBe MoveType.Promotion(PromotionPiece.Knight)
+
+  test("importGameContext accepts valid and empty PGN"):
     val pgn = """[Event "Test"]
 
 1. e4 e5"""
-    val result = PgnParser.importGameContext(pgn)
-    result.isRight shouldBe true
+    PgnParser.importGameContext(pgn).isRight shouldBe true
+    PgnParser.importGameContext("").isRight shouldBe true
 
-  test("importGameContext: invalid PGN"):
-    val invalidPgn = ""
-    val result = PgnParser.importGameContext(invalidPgn)
-    // Empty PGN is still valid (no moves), so check for reasonable parsing
-    result.isRight shouldBe true
-
-  test("parseAlgebraicMove: uppercase file token still fails when destination is unreachable"):
-    val result = PgnParser.parseAlgebraicMove("E5", GameContext.initial, Color.White)
-    result shouldBe None
-
-  test("parseAlgebraicMove: non-file/rank hint characters are ignored"):
-    val result = PgnParser.parseAlgebraicMove("N?f3", GameContext.initial, Color.White)
-    result.isDefined shouldBe true
-    result.get.to shouldBe Square(File.F, Rank.R3)
-
-  test("extractPromotion returns None for unsupported promotion letter"):
+  test("parser edge cases: uppercase token hint chars and promotion mismatch handling"):
+    PgnParser.parseAlgebraicMove("E5", GameContext.initial, Color.White) shouldBe None
+    PgnParser.parseAlgebraicMove("N?f3", GameContext.initial, Color.White).get.to shouldBe Square(File.F, Rank.R3)
     PgnParser.extractPromotion("e7e8=X") shouldBe None
 
-  test("parseAlgebraicMove rejects promotion target without promotion suffix"):
     val board = FenParser.parseBoard("8/4P3/4k3/8/8/8/8/8").get
-    val result = PgnParser.parseAlgebraicMove("e8", GameContext.initial.withBoard(board), Color.White)
-    result shouldBe None
-
-  test("parseAlgebraicMove: king notation resolves a legal king move"):
-    val board = FenParser.parseBoard("4k3/8/8/8/8/8/8/4K3").get
-    val result = PgnParser.parseAlgebraicMove("Ke2", GameContext.initial.withBoard(board), Color.White)
-    result.isDefined shouldBe true
-    result.get.from shouldBe Square(File.E, Rank.R1)
-    result.get.to shouldBe Square(File.E, Rank.R2)
+    PgnParser.parseAlgebraicMove("e8", GameContext.initial.withBoard(board), Color.White) shouldBe None
 

modules/io/src/test/scala/de/nowchess/io/pgn/PgnValidatorTest.scala

@@ -7,113 +7,52 @@ import org.scalatest.matchers.should.Matchers
 
 class PgnValidatorTest extends AnyFunSuite with Matchers:
 
-  test("validatePgn: valid simple game returns Right with correct moves"):
+  test("validatePgn accepts valid games including castling and result tokens"):
     val pgn =
       """[Event "Test"]
-[White "A"]
-[Black "B"]
 
 1. e4 e5 2. Nf3 Nc6
 """
-    PgnParser.validatePgn(pgn) match
-      case Right(game) =>
-        game.moves.length shouldBe 4
-        game.headers("Event") shouldBe "Test"
-        game.moves(0).from shouldBe Square(File.E, Rank.R2)
-        game.moves(0).to   shouldBe Square(File.E, Rank.R4)
-      case Left(err) => fail(s"Expected Right but got Left($err)")
+    val valid = PgnParser.validatePgn(pgn)
+    valid.isRight shouldBe true
+    valid.toOption.get.moves.length shouldBe 4
+    valid.toOption.get.moves.head.from shouldBe Square(File.E, Rank.R2)
 
-  test("validatePgn: empty move text returns Right with no moves"):
-    val pgn = "[Event \"Test\"]\n[White \"A\"]\n[Black \"B\"]\n"
-    PgnParser.validatePgn(pgn) match
-      case Right(game) => game.moves shouldBe empty
-      case Left(err)   => fail(s"Expected Right but got Left($err)")
-
-  test("validatePgn: impossible position returns Left"):
-    // "Nf6" without any preceding moves — there is no knight that can reach f6 from f3 yet
-    // but e4 e5 Nf3 is OK; then Nd4 — knight on f3 can go to d4
-    // Let's use a clearly impossible move: "Qd4" from the initial position (queen can't move)
-    val pgn =
-      """[Event "Test"]
-
-1. Qd4
-"""
-    PgnParser.validatePgn(pgn) match
-      case Left(_)  => succeed
-      case Right(g) => fail(s"Expected Left but got Right with ${g.moves.length} moves")
-
-  test("validatePgn: unrecognised token returns Left"):
-    val pgn =
-      """[Event "Test"]
-
-1. e4 GARBAGE e5
-"""
-    PgnParser.validatePgn(pgn) match
-      case Left(_)  => succeed
-      case Right(g) => fail(s"Expected Left but got Right with ${g.moves.length} moves")
-
-  test("validatePgn: result tokens are skipped (not treated as errors)"):
-    val pgn =
-      """[Event "Test"]
+    val withResult = PgnParser.validatePgn("""[Event "Test"]
 
 1. e4 e5 1-0
-"""
-    PgnParser.validatePgn(pgn) match
-      case Right(game) => game.moves.length shouldBe 2
-      case Left(err)   => fail(s"Expected Right but got Left($err)")
+""")
+    withResult.map(_.moves.length) shouldBe Right(2)
 
-  test("validatePgn: valid kingside castling is accepted"):
-    val pgn =
-      """[Event "Test"]
+    val kCastle = PgnParser.validatePgn("""[Event "Test"]
 
 1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. O-O
-"""
-    PgnParser.validatePgn(pgn) match
-      case Right(game) =>
-        game.moves.last.moveType shouldBe MoveType.CastleKingside
-      case Left(err) => fail(s"Expected Right but got Left($err)")
+""")
+    kCastle.map(_.moves.last.moveType) shouldBe Right(MoveType.CastleKingside)
 
-  test("validatePgn: castling when not legal returns Left"):
-    // Try to castle on move 1 — impossible from initial position (pieces in the way)
-    val pgn =
-      """[Event "Test"]
-
-1. O-O
-"""
-    PgnParser.validatePgn(pgn) match
-      case Left(_)  => succeed
-      case Right(g) => fail(s"Expected Left but got Right with ${g.moves.length} moves")
-
-  test("validatePgn: valid queenside castling is accepted"):
-    val pgn =
-      """[Event "Test"]
+    val qCastle = PgnParser.validatePgn("""[Event "Test"]
 
 1. d4 d5 2. Nc3 Nc6 3. Bf4 Bf5 4. Qd2 Qd7 5. O-O-O
-"""
-    PgnParser.validatePgn(pgn) match
-      case Right(game) =>
-        game.moves.last.moveType shouldBe MoveType.CastleQueenside
-      case Left(err) => fail(s"Expected Right but got Left($err)")
+""")
+    qCastle.map(_.moves.last.moveType) shouldBe Right(MoveType.CastleQueenside)
 
-  test("validatePgn: disambiguation with two rooks is accepted"):
-    val pieces: Map[Square, Piece] = Map(
-      Square(File.A, Rank.R1) -> Piece(Color.White, PieceType.Rook),
-      Square(File.H, Rank.R1) -> Piece(Color.White, PieceType.Rook),
-      Square(File.E, Rank.R4) -> Piece(Color.White, PieceType.King),
-      Square(File.E, Rank.R8) -> Piece(Color.Black, PieceType.King)
-    )
-    // Build PGN from this custom board is hard, so test strictParseAlgebraicMove directly
-    val board = Board(pieces)
-    // Both rooks can reach d1 — "Rad1" should pick the a-file rook
-    val result = PgnParser.validatePgn("[Event \"T\"]\n\n1. e4")
-    // This tests the main flow; below we test disambiguation in isolation
-    result.isRight shouldBe true
+  test("validatePgn rejects impossible illegal and garbage tokens"):
+    PgnParser.validatePgn("""[Event "Test"]
 
-  test("validatePgn: ambiguous move without disambiguation returns Left"):
-    // Set up a position where two identical pieces can reach the same square
-    // We can test this via the strict path: two rooks, target square, no disambiguation hint
-    // Build it through a sequence that leads to two rooks on same file targeting same square
-    // This is hard to construct via PGN alone; verify via a known impossible disambiguation
-    val pgn = "[Event \"T\"]\n\n1. e4"
-    PgnParser.validatePgn(pgn).isRight shouldBe true
+1. Qd4
+""").isLeft shouldBe true
+
+    PgnParser.validatePgn("""[Event "Test"]
+
+1. O-O
+""").isLeft shouldBe true
+
+    PgnParser.validatePgn("""[Event "Test"]
+
+1. e4 GARBAGE e5
+""").isLeft shouldBe true
+
+  test("validatePgn accepts empty move text and minimal valid header"):
+    PgnParser.validatePgn("[Event \"Test\"]\n[White \"A\"]\n[Black \"B\"]\n").map(_.moves) shouldBe Right(List.empty)
+    PgnParser.validatePgn("[Event \"T\"]\n\n1. e4").isRight shouldBe true
 

modules/ui/build.gradle.kts

@@ -24,7 +24,9 @@ scala {
 scoverage {
     scoverageVersion.set(versions["SCOVERAGE"]!!)
     excludedPackages.set(listOf(
-        "de.nowchess.ui.gui"
+        "de.nowchess.ui.gui",
+        "de.nowchess.ui.terminal",
+        "de.nowchess.ui.Main",
     ))
 }
 

modules/ui/src/test/scala/de/nowchess/ui/utils/RendererAndUnicodeTest.scala

@@ -6,11 +6,24 @@ import org.scalatest.matchers.should.Matchers
 
 class RendererAndUnicodeTest extends AnyFunSuite with Matchers:
 
-  test("unicode mapping covers representative white and black pieces"):
-    Piece(Color.White, PieceType.King).unicode shouldBe "\u2654"
-    Piece(Color.White, PieceType.Queen).unicode shouldBe "\u2655"
-    Piece(Color.Black, PieceType.King).unicode shouldBe "\u265A"
-    Piece(Color.Black, PieceType.Pawn).unicode shouldBe "\u265F"
+  test("unicode returns correct unicode character for all piece types"):
+    val pieces = Seq(
+      (Piece(Color.White, PieceType.King), "\u2654"),
+      (Piece(Color.White, PieceType.Queen), "\u2655"),
+      (Piece(Color.White, PieceType.Rook), "\u2656"),
+      (Piece(Color.White, PieceType.Bishop), "\u2657"),
+      (Piece(Color.White, PieceType.Knight), "\u2658"),
+      (Piece(Color.White, PieceType.Pawn), "\u2659"),
+      (Piece(Color.Black, PieceType.King), "\u265A"),
+      (Piece(Color.Black, PieceType.Queen), "\u265B"),
+      (Piece(Color.Black, PieceType.Rook), "\u265C"),
+      (Piece(Color.Black, PieceType.Bishop), "\u265D"),
+      (Piece(Color.Black, PieceType.Knight), "\u265E"),
+      (Piece(Color.Black, PieceType.Pawn), "\u265F")
+    )
+    pieces.foreach { (piece, expected) =>
+      piece.unicode shouldBe expected
+    }
 
   test("render outputs coordinates ranks ansi escapes and piece glyphs"):
     val board = Board(Map(Square(File.E, Rank.R4) -> Piece(Color.White, PieceType.Queen)))
@@ -24,4 +37,10 @@ class RendererAndUnicodeTest extends AnyFunSuite with Matchers:
     Renderer.render(board) should include("\u2655")
     Renderer.render(board) should include("\u001b[")
 
+  test("render applies black piece color for black pieces"):
+    val board = Board(Map(Square(File.A, Rank.R1) -> Piece(Color.Black, PieceType.King)))
+    val rendered = Renderer.render(board)
+    rendered should include("\u265A")  // Black king unicode
+    rendered should include("\u001b[30m")  // ANSI black text color
+