Test rendering all deleted and changed content files (#42420)

.github/workflows/test-changed-content.yml

@@ -0,0 +1,55 @@
+name: Test changed content
+
+# **What it does**: Runs the jest tests for changed and deleted content files.
+# **Why we have it**: Use GitHub Actions to run tests on changed content files.
+# **Who does it impact**: Docs engineering, open-source engineering contributors.
+
+on:
+  pull_request:
+    branches:
+      # This is important! If you make a PR against a megabranch, you
+      # might actually want to delete a file without setting up a
+      # redirect in its place. But if it's going into `main` we'll
+      # want to make sure that doesn't happen.
+      - main
+    paths:
+      - 'content/**'
+
+permissions:
+  contents: read
+
+jobs:
+  test-changed-content:
+    runs-on: ${{ fromJSON('["ubuntu-latest", "ubuntu-20.04-xl"]')[github.repository == 'github/docs-internal'] }}
+    steps:
+      # Each of these ifs needs to be repeated at each step to make sure the required check still runs
+      # Even if if doesn't do anything
+      - name: Check out repo
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
+        with:
+          # See https://github.com/tj-actions/changed-files#on-pull_request-
+          fetch-depth: 2
+
+      - uses: ./.github/actions/node-npm-setup
+
+      - uses: ./.github/actions/get-docs-early-access
+        if: ${{ github.repository == 'github/docs-internal' }}
+        with:
+          token: ${{ secrets.DOCS_BOT_PAT_READPUBLICKEY }}
+
+      - uses: ./.github/actions/cache-nextjs
+
+      - name: Run build script
+        run: npm run build
+
+      - name: Get changed files
+        id: changed-files
+        uses: tj-actions/changed-files@246636f5fa148b5ad8e65ca4c57b18af3123e5f6 # v39.0.1
+        with:
+          files: 'content/**'
+
+      - name: Run tests
+        env:
+          CHANGED_FILES: ${{ steps.changed-files.outputs.modified_files }}
+          DELETED_FILES: ${{ steps.changed-files.outputs.deleted_files }}
+        run: npm test -- src/content-render/tests/render-changed-and-deleted-files.js