test: create some hooks and utils test script, modified clipboard test script (#27928)

web/hooks/use-document-title.spec.ts

@@ -1,3 +1,15 @@
+/**
+ * Test suite for useDocumentTitle hook
+ *
+ * This hook manages the browser document title with support for:
+ * - Custom branding (when enabled in system features)
+ * - Default "Dify" branding
+ * - Pending state handling (prevents title flicker during loading)
+ * - Page-specific titles with automatic suffix
+ *
+ * Title format: "[Page Title] - [Brand Name]"
+ * If no page title: "[Brand Name]"
+ */
 import { defaultSystemFeatures } from '@/types/feature'
 import { act, renderHook } from '@testing-library/react'
 import useDocumentTitle from './use-document-title'
@@ -7,6 +19,10 @@ jest.mock('@/service/common', () => ({
   getSystemFeatures: jest.fn(() => ({ ...defaultSystemFeatures })),
 }))
 
+/**
+ * Test behavior when system features are still loading
+ * Title should remain empty to prevent flicker
+ */
 describe('title should be empty if systemFeatures is pending', () => {
   act(() => {
     useGlobalPublicStore.setState({
@@ -14,16 +30,26 @@ describe('title should be empty if systemFeatures is pending', () => {
       isGlobalPending: true,
     })
   })
+  /**
+   * Test that title stays empty during loading even when a title is provided
+   */
   it('document title should be empty if set title', () => {
     renderHook(() => useDocumentTitle('test'))
     expect(document.title).toBe('')
   })
+  /**
+   * Test that title stays empty during loading when no title is provided
+   */
   it('document title should be empty if not set title', () => {
     renderHook(() => useDocumentTitle(''))
     expect(document.title).toBe('')
   })
 })
 
+/**
+ * Test default Dify branding behavior
+ * When custom branding is disabled, should use "Dify" as the brand name
+ */
 describe('use default branding', () => {
   beforeEach(() => {
     act(() => {
@@ -33,17 +59,29 @@ describe('use default branding', () => {
       })
     })
   })
+  /**
+   * Test title format with page title and default branding
+   * Format: "[page] - Dify"
+   */
   it('document title should be test-Dify if set title', () => {
     renderHook(() => useDocumentTitle('test'))
     expect(document.title).toBe('test - Dify')
   })
 
+  /**
+   * Test title with only default branding (no page title)
+   * Format: "Dify"
+   */
   it('document title should be Dify if not set title', () => {
     renderHook(() => useDocumentTitle(''))
     expect(document.title).toBe('Dify')
   })
 })
 
+/**
+ * Test custom branding behavior
+ * When custom branding is enabled, should use the configured application_title
+ */
 describe('use specific branding', () => {
   beforeEach(() => {
     act(() => {
@@ -53,11 +91,19 @@ describe('use specific branding', () => {
       })
     })
   })
+  /**
+   * Test title format with page title and custom branding
+   * Format: "[page] - [Custom Brand]"
+   */
   it('document title should be test-Test if set title', () => {
     renderHook(() => useDocumentTitle('test'))
     expect(document.title).toBe('test - Test')
   })
 
+  /**
+   * Test title with only custom branding (no page title)
+   * Format: "[Custom Brand]"
+   */
   it('document title should be Test if not set title', () => {
     renderHook(() => useDocumentTitle(''))
     expect(document.title).toBe('Test')