Add pre-publish smoke test (#369)

* Add scaffolding for smoke tests

* Impelement percentile based smoke test

* Add changes from PR testing

* fix spelling

* Add newline

* Update needs

Author: bryan-aguilar

.github/workflows/main.yml

@@ -1,12 +1,16 @@
 name: Gatsby Publish
 
+env:
+  DELTA_THRESHOLD: .90
+
 on:
   push:
     branches:
       - main
+    
 
 jobs:
-  build:
+  publish-smoke-test:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v1
@@ -15,5 +19,54 @@ jobs:
           GH_API_KEY: ${{ secrets.GITHUB_TOKEN }}
         with:
           access-token: ${{ secrets.demo }}
-          deploy-branch: gh-pages
-#          gatsby-args: --prefix-paths
+          deploy-branch: smoke-test
+  verify-smoke-test:
+    runs-on: ubuntu-latest
+    needs: publish-smoke-test
+    steps:
+      - name: Checkout Smoke Test Branch
+        uses: actions/checkout@v3
+        with:
+          path: smoke-test
+          ref: smoke-test
+      - name: Calculate total lines in smoke-test branch
+        run: |
+          export ST_LC=$(find ./smoke-test -type f -print0 | wc -l --files0=- | tail -n 1 | cut -d ' ' -f 1)
+          echo $ST_LC
+          echo "SMOKE_TEST_LINE_COUNT=$ST_LC" >> $GITHUB_ENV
+      - name: Checkout Published Branch
+        uses: actions/checkout@v3
+        with:
+          path: published
+          ref: gh-pages
+      - name: Calculate total lines in published branch
+        run: |
+          export PUB_LC=$(find ./published -type f -print0 | wc -l --files0=- | tail -n 1 | cut -d ' ' -f 1)
+          echo $PUB_LC
+          echo "PUBLISHED_LINE_COUNT=$PUB_LC" >> $GITHUB_ENV
+      - name: Generate percentile diff
+        run: |
+          export PERCENTILE_DIFF=$(bc<<<"scale=2;${{ env.SMOKE_TEST_LINE_COUNT}} / ${{ env.PUBLISHED_LINE_COUNT }}")
+          echo $PERCENTILE_DIFF
+          if [ 1 -eq $(bc<<<"$PERCENTILE_DIFF < ${{ env.DELTA_THRESHOLD }}") ]; then
+            exit 1
+          else
+            exit 0
+          fi
+
+  publish-live:
+    needs: verify-smoke-test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          ref: gh-pages
+      - name: merge commit push
+        env:
+          GITHUB_TOKEN: ${{ secrets.demo }}
+        run: |
+          git config --global user.name 'Gatsby Publish Workflow'
+          git config --global user.email '[email protected]'
+          git fetch --all
+          git reset --hard origin/smoke-test
+          git push -f origin gh-pages