test: add tests for undo and redo notifications in GameEngine

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
+  }
 }