Ensure index files have children (#59194)

Author: sarahs

package-lock.json

@@ -0,0 +1,6 @@
+---
+title: This is an index page
+intro: 'I am missing a children frontmatter property'
+versions:
+  fpt: '*'
+---

src/fixtures/fixtures/index.md

@@ -2,6 +2,6 @@
 title: A sample TOC
 versions:
   free-pro-team: '*'
+children:
+  - /article-one
 ---
-
-{% link_in_list /sample-article %}

src/fixtures/fixtures/sample-toc-index.md

@@ -6,7 +6,6 @@ import getApplicableVersions from '@/versions/lib/get-applicable-versions'
 import generateRedirectsForPermalinks from '@/redirects/lib/permalinks'
 import getEnglishHeadings from '@/languages/lib/get-english-headings'
 import { getAlertTitles } from '@/languages/lib/get-alert-titles'
-import getTocItems from './get-toc-items'
 import Permalink from './permalink'
 import { renderContent } from '@/content-render/index'
 import processLearningTracks from '@/learning-track/lib/process-learning-tracks'
@@ -100,6 +99,8 @@ class Page {
   public rawRecommended?: string[]
   public autogenerated?: string
   public featuredLinks?: FeaturedLinksExpanded
+  public children?: string[]
+  public layout?: string
 
   // Derived properties
   public languageCode!: string
@@ -111,7 +112,6 @@ class Page {
   public documentType: string
   public applicableVersions: string[]
   public permalinks: Permalink[]
-  public tocItems?: any[]
   public communityRedirect?: CommunityRedirect
   public detectedPlatforms: string[] = []
   public includesPlatformSpecificContent: boolean = false
@@ -259,9 +259,13 @@ class Page {
       this.applicableVersions,
     )
 
+    // Ensure 'children' frontmatter exists if this is a standard index page
     if (this.relativePath.endsWith('index.md')) {
-      // get an array of linked items in product and category TOCs
-      this.tocItems = getTocItems(this)
+      if (!this.children && !/(search|early-access)\/.*index.md/.test(this.relativePath)) {
+        if (this.layout !== 'journey-landing') {
+          throw new Error(`${this.fullPath} must contain 'children' frontmatter.`)
+        }
+      }
     }
 
     // if this is an article and it doesn't have showMiniToc = false, set mini TOC to true

src/frame/lib/get-toc-items.ts

@@ -439,6 +439,18 @@ describe('catches errors thrown in Page class', () => {
     await expect(getPage).rejects.toThrowError('versions')
   })
 
+  test('missing children frontmatter in index file', async () => {
+    async function getPage() {
+      return await Page.init({
+        relativePath: 'index.md',
+        basePath: path.join(__dirname, '../../../src/fixtures/fixtures'),
+        languageCode: 'en',
+      })
+    }
+
+    await expect(getPage).rejects.toThrowError(/must contain 'children' frontmatter/)
+  })
+
   test('English page with a version in frontmatter that its parent product is not available in', async () => {
     async function getPage() {
       return await Page.init({