diff --git a/lab2/main_test.js b/lab2/main_test.js
index 5034468e..e2373f1e 100644
--- a/lab2/main_test.js
+++ b/lab2/main_test.js
@@ -1,6 +1,76 @@
+
 const test = require('node:test');
 const assert = require('assert');
+const fs = require('fs');
+
+// 模擬 fs.readFile ，返回假數據
+test.mock.method(fs, 'readFile', (file, options, callback) => {
+    callback(null, 'Alice\njohn\nBob');
+});
+
+// 從 main.js 導入 Application 和 MailSystem 類
 const { Application, MailSystem } = require('./main');
 
-// TODO: write your tests here
-// Remember to use Stub, Mock, and Spy when necessary
\ No newline at end of file
+// testMailSystem_write() 
+test('MailSystem_write()', () => {
+    const ms = new MailSystem();
+    assert.equal(ms.write('Alice'), 'Congrats, Alice!');
+    assert.equal(ms.write(null), 'Congrats, null!');
+    assert.equal(ms.write(512558020), 'Congrats, 512558020!');  
+});
+
+// test MailSystem_send() 
+test('MailSystem_send()', () => {
+    const ms = new MailSystem();
+    const name = 'Alice';
+    test.mock.method(Math, 'random', () => 0.6);                      
+    assert.equal(ms.send(name, 'success'), true);             
+    test.mock.method(Math, 'random', () => 0.4);                     
+    assert.equal(ms.send(name, 'fail'), false);                 
+});
+
+// test Application_getNames() 
+test('Application_getNames()', async () => {
+    const app = new Application();
+    const name_list = ['Alice', 'john', 'Bob'];
+    const names = await app.getNames();
+    assert.deepStrictEqual(names, [name_list, []]);                   
+});
+
+// test Application_getRandomPerson() 
+test('Application_getRandomPerson()', async () => {
+    const app = new Application();
+    const names = await app.getNames();
+    const randomPerson = app.getRandomPerson();
+    assert.ok(names[0].includes(randomPerson));                       
+});
+
+// test Application_selectNextPerson() 
+test('Application_selectNextPerson()', async () => {
+    const app = new Application();
+    const names = await app.getNames();
+    app.selected = ['Alice'];
+    let cnt = 0;
+    test.mock.method(app, 'getRandomPerson', () => {
+        if (cnt <= names[0].length) { 
+            return names[0][cnt++]; 
+        }
+    });
+    assert.strictEqual(app.selectNextPerson(), 'john');               
+    assert.deepStrictEqual(app.selected, ['Alice', 'john']);          
+    assert.strictEqual(app.selectNextPerson(), 'Bob');                
+    assert.deepStrictEqual(app.selected, ['Alice', 'john', 'Bob']);   
+    assert.strictEqual(app.selectNextPerson(), null);                 
+});
+
+// test Application_notifySelected() 
+test('Application_notifySelected()', async () => {
+    const app = new Application();
+    app.people = ['Alice', 'john', 'Bob'];
+    app.selected = ['Alice', 'john', 'Bob'];
+    app.mailSystem.send = test.mock.fn(app.mailSystem.send);
+    app.mailSystem.write = test.mock.fn(app.mailSystem.write);
+    app.notifySelected();
+    assert.strictEqual(app.mailSystem.send.mock.calls.length, 3);     
+    assert.strictEqual(app.mailSystem.write.mock.calls.length, 3);    
+});