Add TaskListTest JUnit test

src/main/java/duke/Duke.java

@@ -47,4 +47,8 @@ public void run() {
             userInput = ui.readCommand();
         }
     }
+
+    public TaskList getTaskList() {
+        return taskList;
+    }
 }

src/main/java/duke/tasks/Task.java

@@ -21,6 +21,10 @@ public void unmark() {
         this.isDone = false;
     }
 
+    public boolean isDone() {
+        return this.isDone;
+    }
+
     public String getStatusIcon() {
         return (isDone ? "X" : " ");
     }

src/test/java/duke/tasks/TaskListTest.java

@@ -0,0 +1,57 @@
+package duke.tasks;
+
+import duke.Duke;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import java.util.ArrayList;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class TaskListTest {
+    private Duke duke;
+
+    @BeforeEach
+    public void setUp() {
+        duke = new Duke("./data/test.txt"); // Use a test file path
+    }
+
+    @Test
+    public void testAddTask() {
+        Task task = new ToDoTask("Task");
+        duke.getTaskList().addTask(task);
+        ArrayList<Task> tasks = duke.getTaskList().getTasks();
+        assertEquals(1, tasks.size());
+        assertEquals(task, tasks.get(0));
+    }
+
+    @Test
+    public void testDeleteTask() {
+        Task task1 = new ToDoTask("Task1");
+        Task task2 = new ToDoTask("Task2");
+        duke.getTaskList().addTask(task1);
+        duke.getTaskList().addTask(task2);
+
+        duke.getTaskList().deleteTask(0);
+        ArrayList<Task> tasks = duke.getTaskList().getTasks();
+        assertEquals(1, tasks.size());
+        assertEquals(task2, tasks.get(0));
+    }
+
+    @Test
+    public void testMarkTaskAsDone() {
+        Task task = new ToDoTask("Task");
+        duke.getTaskList().addTask(task);
+        duke.getTaskList().markTaskAsDone(0);
+        ArrayList<Task> tasks = duke.getTaskList().getTasks();
+        assertEquals(true, tasks.get(0).isDone());
+    }
+
+    @Test
+    public void testUnmarkTask() {
+        Task task = new ToDoTask("Task");
+        duke.getTaskList().addTask(task);
+        duke.getTaskList().markTaskAsDone(0);
+        duke.getTaskList().unmarkTask(0);
+        ArrayList<Task> tasks = duke.getTaskList().getTasks();
+        assertEquals(false, tasks.get(0).isDone());
+    }
+}