percy visual tests via CI

.github/workflows/ci.yml

@@ -1,6 +1,10 @@
 name: CI
 
-on: [push, pull_request]
+on:
+  push:
+    branches:
+    - master
+  pull_request:
 
 jobs:
   deploy:
@@ -9,7 +13,7 @@ jobs:
     steps:
     - uses: actions/setup-node@v1
       with:
-        node-version: 12.x
+        node-version: '12.x'
     - name: Install netlify-cli
       run: npm install -g netlify-cli
     - name: Wait for Netlify
@@ -26,7 +30,7 @@ jobs:
     - uses: actions/checkout@v2
     - uses: actions/setup-node@v1
       with:
-        node-version: 12.x
+        node-version: '12.x'
     - name: Install LHCI
       run: npm install -g @lhci/cli
     - name: Audit deploy preview
@@ -56,4 +60,49 @@ jobs:
       uses: actions/upload-artifact@v1
       with:
         name: lhci-results
-        path: ./.lighthouseci
+        path: './.lighthouseci'
+
+  build:
+    runs-on: ubuntu-latest
+    if: "!contains(github.event.head_commit.message, '[skip ci]')"
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        fetch-depth: 1
+        lfs: false
+    - uses: actions/setup-node@v1
+      with:
+        node-version: '12.x'
+    # https://github.com/actions/cache/blob/master/examples.md#node---yarn
+    # https://github.com/actions/cache/issues/60
+    - name: Get yarn cache location
+      id: yarn-cache
+      run: echo "::set-output name=dir::$(yarn cache dir)"
+    - name: Cache dependencies
+      uses: actions/cache@v1
+      with:
+        path: ${{ steps.yarn-cache.outputs.dir }}
+        key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}
+        restore-keys: |
+          ${{ runner.os }}-yarn-
+    - run: yarn install --no-ignore-optional --frozen-lockfile
+    - run: yarn build:preview
+    - uses: actions/upload-artifact@v1
+      with:
+        name: public
+        path: './public'
+
+  percy:
+    runs-on: ubuntu-latest
+    if: "!contains(github.event.head_commit.message, '[skip ci]')"
+    needs: build
+    steps:
+    - uses: actions/download-artifact@v1
+      with:
+        name: public
+    - uses: percy/snapshot-action@v0.1.0
+      with:
+        build-directory: public
+        flags: --snapshot-files "**/index.html,notes/**/amp.html"
+      env:
+        PERCY_TOKEN: ${{ secrets.PERCY_TOKEN }}