Add junit test to class TestList

src/test/java/tasklist/TaskListTest.java

@@ -0,0 +1,27 @@
+package tasklist;
+
+import org.junit.jupiter.api.Test;
+import task.Todo;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class TaskListTest {
+    @Test
+    public void markTest(){
+        TaskList currTask = new TaskList();
+        currTask.addTask(new Todo("Testing"));
+        String actual = currTask.mark(0);
+        assertEquals("\t    [T][X] Testing\n", actual);
+    }
+
+    @Test
+    public void unmarkTest(){
+        TaskList currTask = new TaskList();
+        currTask.addTask(new Todo("Testing"));
+        currTask.mark(0);
+        String actual = currTask.unmark(0);
+
+        assertEquals("\t    [T][ ] Testing\n", actual);
+    }
+}
+