test: add unit tests for isPasswordValid utility (#30)

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: sunnylqm <615282+sunnylqm@users.noreply.github.com>

Author: sunnylqm

src/utils/helper.test.ts

@@ -1,5 +1,35 @@
 import { describe, expect, test } from 'bun:test';
-import { isExpVersion } from './helper';
+import { isExpVersion, isPasswordValid } from './helper';
+
+describe('isPasswordValid', () => {
+  test('should return true for valid passwords', () => {
+    expect(isPasswordValid('Passw0rd')).toBe(true);
+    expect(isPasswordValid('UPPER123')).toBe(true);
+    expect(isPasswordValid('Valid123')).toBe(true);
+  });
+
+  test('should return false for passwords that are too short', () => {
+    expect(isPasswordValid('Short')).toBe(false); // 5 chars
+    expect(isPasswordValid('A1b')).toBe(false); // 3 chars
+  });
+
+  test('should return false for passwords that are too long', () => {
+    expect(isPasswordValid('ThisPasswordIsWayTooLong123')).toBe(false); // > 16 chars
+  });
+
+  test('should return false for passwords with only digits', () => {
+    expect(isPasswordValid('12345678')).toBe(false);
+  });
+
+  test('should return false for passwords with only lowercase letters', () => {
+    expect(isPasswordValid('lowercase')).toBe(false);
+  });
+
+  test('should return false for passwords with no uppercase letters', () => {
+    expect(isPasswordValid('lower123')).toBe(false);
+    expect(isPasswordValid('noupper!')).toBe(false);
+  });
+});
 
 describe('isExpVersion', () => {
   test('should return false when config is null', () => {