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/wiki.test.ts

@@ -2,9 +2,7 @@ import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import { fetchWikiPage, fetchWikiPageByTitle, fetchWikiPages } from '@/lib/wiki'
 
-const api = vi.hoisted (() => ({
-  apiGet: vi.fn (),
-}))
+const api = vi.hoisted (() => ({ apiGet: vi.fn () }))
 
 vi.mock ('@/lib/api', () => api)
 
@@ -21,28 +19,37 @@ describe ('wiki API functions', () => {
     await fetchWikiPage ('1', { version: '3' })
 
     expect (api.apiGet).toHaveBeenNthCalledWith (
-        1,
-        '/wiki',
-        { params: { title: '虹' } },
-    )
+	1,
+	'/wiki',
+	{ params: { title: '虹' } })
     expect (api.apiGet).toHaveBeenNthCalledWith (
-        2,
-        '/wiki/1',
-        { params: { version: '3' } },
-    )
+	2,
+	'/wiki/1',
+	{ params: { version: '3' } })
   })
 
   it ('encodes title path segments and returns null on misses', async () => {
     api.apiGet.mockResolvedValueOnce ({ id: 2 })
-    api.apiGet.mockRejectedValueOnce (new Error ('missing'))
+    api.apiGet.mockRejectedValueOnce ({ isAxiosError: true, response: { status: 404 } })
 
     await fetchWikiPageByTitle ('a/b c', { version: undefined })
-    await expect (fetchWikiPageByTitle ('missing', {})).resolves.toBeNull ()
+    await expect (fetchWikiPageByTitle ('missing', { })).resolves.toBeNull ()
 
     expect (api.apiGet).toHaveBeenNthCalledWith (
-        1,
-        '/wiki/title/a%2Fb%20c',
-        { params: { version: undefined } },
-    )
+	1,
+	'/wiki/title/a%2Fb%20c',
+	{ params: { version: undefined } })
+  })
+
+  it.each ([403, 500]) ('preserves HTTP %s errors', async status => {
+    const error = { isAxiosError: true, response: { status } }
+    api.apiGet.mockRejectedValueOnce (error)
+    await expect (fetchWikiPageByTitle ('ホーム', { })).rejects.toBe (error)
+  })
+
+  it ('preserves network failures for callers', async () => {
+    const error = new Error ('network failure')
+    api.apiGet.mockRejectedValueOnce (error)
+    await expect (fetchWikiPageByTitle ('ホーム', { })).rejects.toBe (error)
   })
 })