Add pa11y-ci for automated accessibility tests

.github/workflows/pa11y.yml

@@ -0,0 +1,54 @@
+name: Tests
+
+on:
+  push:
+    branches-ignore:
+      - "dependabot/**"
+  pull_request:
+
+env:
+  FORCE_COLOR: 2
+  NODE: 16
+
+jobs:
+  docs:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v2
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v2
+        with:
+          node-version: "${{ env.NODE }}"
+          cache: npm
+
+      - run: java -version
+
+      - name: Install npm dependencies
+        run: npm ci
+
+      - name: Compile dist
+        run: npm run dist
+
+      - name: Update sri
+        run: npm run release-sri
+
+      - name: Test docs
+        run: npm run docs-build
+
+      - name: Run accessibility tests
+        run: npm run docs-accessibility-json
+
+      - name: Generate HTML accessibility results
+        run: npm run docs-pa11y-html
+        if: failure()
+
+      - name: Upload accessibility results
+        uses: actions/upload-artifact@v2
+        if: failure()
+        with:
+          name: pa11y-ci-results
+          path: pa11y-ci-report/
+          if-no-files-found: error

.gitignore

@@ -39,3 +39,7 @@ Thumbs.db
 # Folders to ignore
 /js/coverage/
 /node_modules/
+
+# Pa11y
+/pa11y-ci-report/
+pa11y-ci-results.json 

build/.pa11yci.json

@@ -0,0 +1,11 @@
+{
+  "standard": "WCAG2AA",
+  "level": "error",
+  "concurrency": 4,
+  "defaults": {
+    "runners": [
+      "htmlcs"
+    ],
+    "hideElements": ""
+  }
+}