refactor: test_history() change

src/test/java/MainFrameTest.java

@@ -20,7 +20,7 @@ public class MainFrameTest {
         GameField gameField = mainFrame.getGameField();
         gameField.setValue(5, 5, 5);
         mainFrame.saveCurrentGameFieldStateToHistory();
-        int field = mainFrame.getHistory().getFirst().getField(5, 5);
+        int field = mainFrame.getHistory().getLast().getField(5, 5);
 
         assertEquals(5, field);
     }