Add unit tests for utils and module pure functions

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/unit/utils/cookieUtil.test.js

@@ -0,0 +1,72 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import {
+  getCookie,
+  setCookie,
+  setCookieWithoutExpiration,
+  deleteCookie,
+} from '@/utils/cookieUtil.js';
+
+describe('cookieUtil', () => {
+  beforeEach(() => {
+    // Clear all cookies before each test
+    document.cookie.split(';').forEach((c) => {
+      const name = c.split('=')[0].trim();
+      if (name) {
+        document.cookie =
+          name + '=; Max-Age=-99999999; path=/';
+      }
+    });
+  });
+
+  describe('getCookie', () => {
+    it('returns null when cookie does not exist', () => {
+      expect(getCookie('nonexistent')).toBeNull();
+    });
+
+    it('returns value of an existing cookie', () => {
+      document.cookie = 'testKey=testValue';
+      expect(getCookie('testKey')).toBe('testValue');
+    });
+
+    it('returns correct value when multiple cookies exist',
+      () => {
+        document.cookie = 'first=aaa';
+        document.cookie = 'second=bbb';
+        document.cookie = 'third=ccc';
+        expect(getCookie('second')).toBe('bbb');
+      });
+
+    it('does not match partial cookie names', () => {
+      document.cookie = 'testKey=value';
+      expect(getCookie('test')).toBeNull();
+    });
+  });
+
+  describe('setCookie', () => {
+    it('sets a cookie with default 1-day expiration', () => {
+      setCookie('myKey', 'myValue');
+      expect(getCookie('myKey')).toBe('myValue');
+    });
+
+    it('sets a cookie with empty value', () => {
+      setCookie('emptyKey', '');
+      expect(getCookie('emptyKey')).toBe('');
+    });
+  });
+
+  describe('setCookieWithoutExpiration', () => {
+    it('sets a session cookie', () => {
+      setCookieWithoutExpiration('sessionKey', 'sessionVal');
+      expect(getCookie('sessionKey')).toBe('sessionVal');
+    });
+  });
+
+  describe('deleteCookie', () => {
+    it('removes an existing cookie', () => {
+      setCookie('toDelete', 'value');
+      expect(getCookie('toDelete')).toBe('value');
+      deleteCookie('toDelete');
+      expect(getCookie('toDelete')).toBeNull();
+    });
+  });
+});