ヘルプを Wiki から分離 (#424) (#430)

画面上でのテストは完了．
移行にす早さが求められるので，準備ができたらマージする．

Reviewed-on: #430
Co-authored-by: miteruzo <miteruzo@naver.com>

frontend/src/lib/helpPrefetch.test.tsx

@@ -0,0 +1,126 @@
+import { QueryClient } from '@tanstack/react-query'
+import { fireEvent, screen, waitFor } from '@testing-library/react'
+import { Route, Routes, useLocation } from 'react-router-dom'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+import PrefetchLink from '@/components/PrefetchLink'
+import * as prefetchers from '@/lib/prefetchers'
+import HelpDetailPage from '@/pages/help/HelpDetailPage'
+import HelpDiffPage from '@/pages/help/HelpDiffPage'
+import { helpFixture } from '@/test/helpFixtures'
+import { renderWithProviders } from '@/test/render'
+
+const settings = vi.hoisted (() => ({ linkPreload: 'intent' }))
+vi.mock ('@/lib/useClientBehaviourSettings', () => ({
+    useClientBehaviourSettings: () => settings }))
+vi.mock ('@/lib/help', async () => (await import ('@/test/helpFixtures')).helpFixture.api)
+
+
+const Location = () => {
+  const location = useLocation ()
+  return <output data-testid="location">{location.pathname}</output>
+}
+
+
+describe ('Help prefetch integration', () => {
+  beforeEach (() => {
+    helpFixture.reset ()
+    settings.linkPreload = 'intent'
+    vi.clearAllMocks ()
+  })
+
+  it.each (['/help', '/help?title=ホーム&text=検索&page=2', '/help/guide', '/help/changes',
+      '/help/guide/diff?from=2026-10-01&to=2026-10-02.10',
+      '/help/%E8%A8%AD%E5%AE%9A%20%E6%89%8B%E9%A0%86?edition=2026-10-03']) (
+      'registers a unique prefetcher for %s', path => {
+	const url = new URL (path, window.location.origin)
+	expect (prefetchers.routePrefetchers.filter (entry => entry.test (url))).toHaveLength (1)
+      })
+
+  it ('loads and reuses the same MDX module for repeated prefetch and display', async () => {
+    const { queryClient } = renderWithProviders (
+	<>
+	  <PrefetchLink to="/help/guide">Help</PrefetchLink>
+	  <Routes>
+	    <Route path="/" element={null}/>
+	    <Route path="/help/:identifier" element={<HelpDetailPage/>}/>
+	  </Routes>
+	</>)
+    const loader = helpFixture.moduleLoads['../../help/guide/editions/ja/2026-10-02.10.mdx']
+    await Promise.all ([
+	prefetchers.prefetchForURL (queryClient, '/help/guide'),
+	prefetchers.prefetchForURL (queryClient, '/help/guide')])
+    expect (loader).toHaveBeenCalledTimes (1)
+    fireEvent.click (screen.getByRole ('link', { name: 'Help' }))
+    await screen.findByRole ('heading', { name: 'ホーム第十版' })
+    expect (loader).toHaveBeenCalledTimes (1)
+  })
+
+  it ('prefetches the requested identifier and edition independently', async () => {
+    const client = new QueryClient ()
+    await prefetchers.prefetchForURL (client, '/help/guide?edition=2026-10-02.3')
+    await prefetchers.prefetchForURL (client, `/help/${encodeURIComponent ('設定 手順')}`)
+    expect (helpFixture.modules['../../help/guide/editions/ja/2026-10-02.3.mdx'])
+	.toHaveBeenCalledTimes (1)
+    expect (helpFixture.modules['../../help/設定 手順/editions/ja/2026-10-03.mdx'])
+	.toHaveBeenCalledTimes (1)
+    expect (helpFixture.modules['../../help/guide/editions/en/2026-10-02.mdx'])
+	.not.toHaveBeenCalled ()
+  })
+
+  it ('loads history editions without treating changes as an article', async () => {
+    const article = vi.spyOn (helpFixture.api, 'getHelpArticle')
+    await prefetchers.prefetchForURL (new QueryClient (), '/help/changes')
+    expect (article).not.toHaveBeenCalledWith ('changes')
+    expect (helpFixture.loads.changes).toHaveBeenCalledTimes (1)
+    Object.values (helpFixture.raw).forEach (load => expect (load).not.toHaveBeenCalled ())
+    Object.values (helpFixture.modules).forEach (load => expect (load).not.toHaveBeenCalled ())
+  })
+
+  it ('reuses two prefetched raw editions when displaying their diff', async () => {
+    const path = '/help/guide/diff?from=2026-10-01&to=2026-10-02.10'
+    const { queryClient } = renderWithProviders (
+	<>
+	  <PrefetchLink to={path}>diff</PrefetchLink>
+	  <Routes>
+	    <Route path="/" element={null}/>
+	    <Route path="/help/:identifier/diff" element={<HelpDiffPage/>}/>
+	  </Routes>
+	</>)
+    await Promise.all ([prefetchers.prefetchForURL (queryClient, path),
+	prefetchers.prefetchForURL (queryClient, path)])
+    fireEvent.click (screen.getByRole ('link', { name: 'diff' }))
+    expect (await screen.findByRole ('link', { name: '旧ホーム (2026-10-01)' }))
+	.toHaveAttribute ('href', '/help/guide?edition=2026-10-01')
+    expect (screen.getByText ('+ # ホーム第十版')).toBeInTheDocument ()
+    Object.entries (helpFixture.raw).forEach (([name, load]) => {
+      const expected = /\/ja\/(2026-10-01|2026-10-02\.10)\.mdx$/.test (name) ? 1 : 0
+      expect (load).toHaveBeenCalledTimes (expected)
+    })
+    Object.values (helpFixture.modules).forEach (load => expect (load).not.toHaveBeenCalled ())
+  })
+
+  it.each (['intent', 'off']) ('respects %s intent settings and still prefetches clicks',
+      async mode => {
+	settings.linkPreload = mode
+	const run = vi.spyOn (prefetchers, 'prefetchForURL').mockResolvedValue ()
+	renderWithProviders (<><Location/><PrefetchLink to="/help/guide">Help</PrefetchLink></>)
+	const link = screen.getByRole ('link', { name: 'Help' })
+	fireEvent.mouseEnter (link)
+	fireEvent.touchStart (link)
+	expect (run).toHaveBeenCalledTimes (mode === 'intent' ? 2 : 0)
+	fireEvent.click (link)
+	await waitFor (() => expect (screen.getByTestId ('location'))
+	    .toHaveTextContent ('/help/guide'))
+	expect (run).toHaveBeenCalledTimes (mode === 'intent' ? 3 : 1)
+      })
+
+  it ('continues navigation after prefetch failure', async () => {
+    vi.spyOn (console, 'error').mockImplementation (() => {})
+    vi.spyOn (prefetchers, 'prefetchForURL').mockRejectedValue (new Error ('offline'))
+    renderWithProviders (<><Location/><PrefetchLink to="/help/guide">Help</PrefetchLink></>)
+    fireEvent.click (screen.getByRole ('link', { name: 'Help' }))
+    await waitFor (() => expect (screen.getByTestId ('location'))
+	.toHaveTextContent ('/help/guide'))
+  })
+})