Add infrastructure to validate GitHub Actions workflows

.github/workflows/check-workflows-task.yml

@@ -0,0 +1,48 @@
+# Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/check-workflows-task.md
+name: Check Workflows
+
+env:
+  # See: https://github.com/actions/setup-node/#readme
+  NODE_VERSION: 16.x
+
+# See: https://docs.github.com/actions/using-workflows/events-that-trigger-workflows
+on:
+  push:
+    paths:
+      - ".github/workflows/*.ya?ml"
+      - "package.json"
+      - "package-lock.json"
+      - "Taskfile.ya?ml"
+  pull_request:
+    paths:
+      - ".github/workflows/*.ya?ml"
+      - "package.json"
+      - "package-lock.json"
+      - "Taskfile.ya?ml"
+  schedule:
+    # Run every Tuesday at 8 AM UTC to catch breakage resulting from changes to the JSON schema.
+    - cron: "0 8 * * TUE"
+  workflow_dispatch:
+  repository_dispatch:
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
+      - name: Install Task
+        uses: arduino/setup-task@v1
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          version: 3.x
+
+      - name: Validate workflows
+        run: task --silent ci:validate

README.md

@@ -10,6 +10,7 @@
 [![Check Python status](https://github.com/arduino/compile-sketches/actions/workflows/check-python-task.yml/badge.svg)](https://github.com/arduino/compile-sketches/actions/workflows/check-python-task.yml)
 [![Check Taskfiles status](https://github.com/arduino/compile-sketches/actions/workflows/check-taskfiles.yml/badge.svg)](https://github.com/arduino/compile-sketches/actions/workflows/check-taskfiles.yml)
 [![Check ToC status](https://github.com/arduino/compile-sketches/actions/workflows/check-toc-task.yml/badge.svg)](https://github.com/arduino/compile-sketches/actions/workflows/check-toc-task.yml)
+[![Check Workflows status](https://github.com/arduino/compile-sketches/actions/workflows/check-workflows-task.yml/badge.svg)](https://github.com/arduino/compile-sketches/actions/workflows/check-workflows-task.yml)
 [![Spell Check status](https://github.com/arduino/compile-sketches/actions/workflows/spell-check-task.yml/badge.svg)](https://github.com/arduino/compile-sketches/actions/workflows/spell-check-task.yml)
 [![Sync Labels status](https://github.com/arduino/compile-sketches/actions/workflows/sync-labels-npm.yml/badge.svg)](https://github.com/arduino/compile-sketches/actions/workflows/sync-labels-npm.yml)
 [![Test Python status](https://github.com/arduino/compile-sketches/actions/workflows/test-python-poetry-task.yml/badge.svg)](https://github.com/arduino/compile-sketches/actions/workflows/test-python-poetry-task.yml)

Taskfile.yml

@@ -11,6 +11,7 @@ tasks:
     desc: Check for problems with the project
     deps:
       - task: action:validate
+      - task: ci:validate
       - task: general:check-formatting
       - task: general:check-spelling
       - task: markdown:check-links
@@ -53,6 +54,34 @@ tasks:
             -s "{{.ACTION_METADATA_SCHEMA_PATH}}" \
             -d "action.yml"
 
+  # Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/assets/check-workflows-task/Taskfile.yml
+  ci:validate:
+    desc: Validate GitHub Actions workflows against their JSON schema
+    vars:
+      # Source: https://github.com/SchemaStore/schemastore/blob/master/src/schemas/json/github-workflow.json
+      WORKFLOW_SCHEMA_URL: https://json.schemastore.org/github-workflow
+      WORKFLOW_SCHEMA_PATH:
+        sh: task utility:mktemp-file TEMPLATE="workflow-schema-XXXXXXXXXX.json"
+      WORKFLOWS_DATA_PATH: "./.github/workflows/*.{yml,yaml}"
+    deps:
+      - task: npm:install-deps
+    cmds:
+      - |
+        wget \
+          --quiet \
+          --output-document="{{.WORKFLOW_SCHEMA_PATH}}" \
+          {{.WORKFLOW_SCHEMA_URL}}
+      - |
+        npx \
+          --package=ajv-cli \
+          --package=ajv-formats \
+          ajv validate \
+            --all-errors \
+            --strict=false \
+            -c ajv-formats \
+            -s "{{.WORKFLOW_SCHEMA_PATH}}" \
+            -d "{{.WORKFLOWS_DATA_PATH}}"
+
   docs:generate:
     desc: Create all generated documentation content
     # This is an "umbrella" task used to call any documentation generation processes the project has.