diff --git a/lab2/main_test.js b/lab2/main_test.js
index 5034468e..301f053c 100644
--- a/lab2/main_test.js
+++ b/lab2/main_test.js
@@ -1,6 +1,121 @@
 const test = require('node:test');
 const assert = require('assert');
 const { Application, MailSystem } = require('./main');
+//write tests use Stub, Mock, and Spy when necessary
+const fs = require('fs');
+const path = require('path');
+test('should name_list.txt ', ()=>{
+    const Listna = 'john\njohn1\njohn2';
+    const tmppa = path.join('name_list.txt');
+    fs.writeFileSync(tmppa,Listna);
+    process.on('exit', () => {
+        if (tmppa) {
+         fs.unlinkSync(tmppa);
+        }
+    });
+});
+//test mailSystem : write()
+test('should be able to write mail', () => {
+    const mailSystem = new MailSystem();
+    assert.strictEqual(mailSystem.write('test'), 'Congrats, test!');
+    assert.strictEqual(mailSystem.write(null), 'Congrats, null!');
+    assert.strictEqual(mailSystem.write(1111), 'Congrats, 1111!');
+});
+// Test MailSystem : send()
+test('should be able to send mail', () => {
+    const mailSystem = new MailSystem();
+    const success = mailSystem.send('test', 'test');
+    test.mock.method(Math, 'random', () => 1);
+    assert.strictEqual(mailSystem.send('ok', 'success'),true);
+    test.mock.method(Math, 'random', () => 0.4);
+    assert.strictEqual(mailSystem.send('fa', 'fail'),false);
+});   
+// Test Application : getNames()
+test('should be able to get names', async () => {
+    const app = new Application();
+    const [names,sel] = await app.getNames('john', 'john1', 'john2');
+    assert.deepStrictEqual(names, ['john', 'john1', 'john2']);
+    assert.deepStrictEqual(sel, []);
+});
+// Test Application : selected
+test('should selected', () => {
+    const app = new Application();
+    app.pe= ['john', 'john1', 'john2'];
+    app.sel = ['john', 'john1', 'john2'];
+    const result = app.selectNextPerson();
+    assert.strictEqual(result, null);
+});
 
-// TODO: write your tests here
-// Remember to use Stub, Mock, and Spy when necessary
\ No newline at end of file
+// Test Application : getRandomPerson()
+test('should be able to get random person',  async (test) => {
+    const app = new Application();
+    const names = await app.getNames();
+    test.mock.method(Math, 'random', () => 0);
+    assert.strictEqual(app.getRandomPerson(), 'john');
+    test.mock.method(Math, 'random', () => 0.4);
+    assert.strictEqual(app.getRandomPerson(), 'john1');
+    test.mock.method(Math, 'random', () => 0.7);
+    assert.strictEqual(app.getRandomPerson(), 'john2');
+    
+});
+// Test Application : selectNextPerson()
+test('should be able to select next person', async (test) => {
+    const app = new Application();
+    const person = await app.getNames();
+    app.selected = ['john'];
+    let cn = 0;
+    test.mock.method(app, 'getRandomPerson', () => {
+        if (cn <= person.length) { 
+            return person[0][cn++]; 
+        }
+     });
+    assert.strictEqual(app.selectNextPerson(), 'john1');
+    assert.deepStrictEqual(app.selected, ['john', 'john1']);
+    assert.strictEqual(app.selectNextPerson(), 'john2');
+    assert.deepStrictEqual(app.selected, ['john', 'john1', 'john2']);
+    assert.strictEqual(app.selectNextPerson(), null);
+ 
+});
+// Test Application : notifySelected()
+test('should be able to notify selected', () => {
+    const app = new Application();
+    app.people = ['john', 'john1', 'john2'];
+    app.selected = ['john', 'john1', 'john2'];
+    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);
+
+});
+
+test('should not been selected ', () => {
+    const app = new Application();
+    let getRandomPersonCallCount = 0;
+    app.getRandomPerson = () => {
+        switch (getRandomPersonCallCount++) {
+            case 0:
+                return 'john';
+            case 1:
+                return 'john1';
+            case 2:
+                return 'john2';
+        }
+    };
+    app.selected = ['john', 'john1'];
+    const result = app.selectNextPerson();
+    assert.strictEqual(result, 'john2'); 
+    assert.strictEqual(getRandomPersonCallCount, 3); 
+});     
+
+test('should write and send person', () => {
+     const app = new Application();
+     this.writeCallCount = 0;
+     this.sendCallCount = 0;
+     this.writeCallCount++;
+     this.sendCallCount++;
+     app.selected = ['john', 'john1', 'john2'];
+    app.notifySelected();
+    assert.strictEqual(this.writeCallCount, 1);
+    assert.strictEqual(this.sendCallCount, 1);
+});