test: add tests for undo and redo notifications in GameEngine

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

@@ -147,12 +147,11 @@ class GameEngine extends Observable:
       val cmd = invoker.history(invoker.getCurrentIndex)
       (cmd: @unchecked) match
         case moveCmd: MoveCommand =>
-          if moveCmd.undo() then
-            moveCmd.previousBoard.foreach(currentBoard = _)
-            moveCmd.previousHistory.foreach(currentHistory = _)
-            moveCmd.previousTurn.foreach(currentTurn = _)
-            invoker.undo()
-            notifyObservers(BoardResetEvent(currentBoard, currentHistory, currentTurn))
+          moveCmd.previousBoard.foreach(currentBoard = _)
+          moveCmd.previousHistory.foreach(currentHistory = _)
+          moveCmd.previousTurn.foreach(currentTurn = _)
+          invoker.undo()
+          notifyObservers(BoardResetEvent(currentBoard, currentHistory, currentTurn))
     else
       notifyObservers(InvalidMoveEvent(currentBoard, currentHistory, currentTurn, "Nothing to undo."))
 
@@ -161,14 +160,10 @@ class GameEngine extends Observable:
       val cmd = invoker.history(invoker.getCurrentIndex + 1)
       (cmd: @unchecked) match
         case moveCmd: MoveCommand =>
-          if moveCmd.execute() then
-            moveCmd.moveResult.foreach {
-              case de.nowchess.chess.command.MoveResult.Successful(newBoard, newHistory, newTurn, captured) =>
-                updateGameState(newBoard, newHistory, newTurn)
-                invoker.redo()
-                emitMoveEvent(moveCmd.from.toString, moveCmd.to.toString, captured, newTurn)
-              case _ => ()
-            }
+          for case de.nowchess.chess.command.MoveResult.Successful(nb, nh, nt, cap) <- moveCmd.moveResult do
+            updateGameState(nb, nh, nt)
+            invoker.redo()
+            emitMoveEvent(moveCmd.from.toString, moveCmd.to.toString, cap, nt)
     else
       notifyObservers(InvalidMoveEvent(currentBoard, currentHistory, currentTurn, "Nothing to redo."))
 

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

@@ -268,6 +268,39 @@ class GameEngineTest extends AnyFunSuite with Matchers:
     val initialEvents = observer.events.size
     engine.processUserInput("q")
     observer.events.size shouldBe initialEvents
+  
+  test("GameEngine undo notifies with BoardResetEvent after successful undo"):
+    val engine = new GameEngine()
+    engine.processUserInput("e2e4")
+    engine.processUserInput("e7e5")
+    val observer = new MockObserver()
+    engine.subscribe(observer)
+    observer.events.clear()
+
+    engine.undo()
+
+    // Should have received a BoardResetEvent on undo
+    observer.events.size should be > 0
+    observer.events.exists(_.isInstanceOf[BoardResetEvent]) shouldBe true
+
+  test("GameEngine redo notifies with MoveExecutedEvent after successful redo"):
+    val engine = new GameEngine()
+    engine.processUserInput("e2e4")
+    engine.processUserInput("e7e5")
+    val boardAfterSecondMove = engine.board
+
+    engine.undo()
+    val observer = new MockObserver()
+    engine.subscribe(observer)
+    observer.events.clear()
+
+    engine.redo()
+
+    // Should have received a MoveExecutedEvent for the redo
+    observer.events.size shouldBe 1
+    observer.events.head shouldBe a[MoveExecutedEvent]
+    engine.board shouldBe boardAfterSecondMove
+    engine.turn shouldBe Color.White
 
   // Mock Observer for testing
   private class MockObserver extends Observer:

modules/ui/src/test/scala/de/nowchess/ui/terminal/TerminalUITest.scala

@@ -166,4 +166,24 @@ class TerminalUITest extends AnyFunSuite with Matchers {
 
     out.toString should include("Captured: Knight(White) on A8") // Depending on how piece/coord serialize
   }
+
+  test("TerminalUI processes valid move input via processUserInput") {
+    val in = new ByteArrayInputStream("e2e4\nq\n".getBytes)
+    val out = new ByteArrayOutputStream()
+
+    val engine = new GameEngine()
+    val ui = new TerminalUI(engine)
+
+    Console.withIn(in) {
+      Console.withOut(out) {
+        ui.start()
+      }
+    }
+
+    val output = out.toString
+    output should include("White's turn.")
+    output should include("Game over. Goodbye!")
+    // The move should have been processed and the board displayed
+    engine.turn shouldBe Color.Black
+  }
 }