chore(md): mdn tweaks

Author: tmm

src/md/rules/mdn.test.ts

@@ -50,6 +50,18 @@ test('lowercases slug in rewritten URL', () => {
   expect(result?.pathname).toBe('/mdn/content/main/files/en-us/web/api/htmlelement/index.md')
 })
 
+test('rewrites locale-less docs URL to mdn/content repo', () => {
+  const rule = mdn()
+  const url = new URL('https://developer.mozilla.org/docs/Web/API/Fetch_API/Using_Fetch')
+  const pattern = rule.patterns[1]
+  assert(pattern instanceof URLPattern)
+  const match = pattern.exec(url)!
+  const result = rule.rewrite!(url, match)
+  expect(result?.href).toBe(
+    'https://raw.githubusercontent.com/mdn/content/main/files/en-us/web/api/fetch_api/using_fetch/index.md',
+  )
+})
+
 // Integration test
 
 test('extract produces expected output for Array.prototype.map', async () => {
@@ -66,6 +78,24 @@ test('extract produces expected output for Array.prototype.map', async () => {
   expect(result.meta.title).toBe('Array.prototype.map()')
 })
 
+test('locale-less docs URL uses markdown source so code fence info stays on the fence', async () => {
+  const md = create({
+    rules: [mdn()],
+    fetch: async (input) => {
+      const url = input instanceof URL ? input.href : typeof input === 'string' ? input : input.url
+      expect(url).toBe(
+        'https://raw.githubusercontent.com/mdn/content/main/files/en-us/web/api/fetch_api/using_fetch/index.md',
+      )
+      return new Response('---\ntitle: Test\n---\n\n```js\nconst x = 1\n```', { status: 200 })
+    },
+  })
+  const result = await md.fetch('https://developer.mozilla.org/docs/Web/API/Fetch_API/Using_Fetch')
+  expect(result.ok).toBe(true)
+  if (!result.ok) return
+  expect(result.content).toContain('```js\nconst x = 1')
+  expect(result.content).not.toContain('\njs\n\n```')
+})
+
 // Extract behavior tests
 
 test('converts jsxref macros to linked inline code', async () => {

src/md/rules/mdn.ts

@@ -5,6 +5,7 @@ export const mdn = defineRule({
   key: 'mdn',
   patterns: [
     new URLPattern({ hostname: 'developer.mozilla.org', pathname: '/:locale/docs/:path+' }),
+    new URLPattern({ hostname: 'developer.mozilla.org', pathname: '/docs/:path+' }),
   ],
   checks: [
     {
@@ -16,7 +17,7 @@ export const mdn = defineRule({
     },
   ],
   rewrite(_url, match) {
-    const locale = match.pathname.groups.locale?.toLowerCase()
+    const locale = match.pathname.groups.locale?.toLowerCase() ?? 'en-us'
     const repo = locale === 'en-us' ? 'mdn/content' : 'mdn/translated-content'
     return new URL(
       `https://raw.githubusercontent.com/${repo}/main/files/${locale}/${match.pathname.groups.path!.toLowerCase()}/index.md`,