Add "smoke test" examples compilation CI workflow

On every push or pull request that affects library source or example files, and periodically, compile all example
sketches for the specified boards.

Author: per1234

.github/workflows/compile-examples.yml

@@ -0,0 +1,82 @@
+name: Compile Examples
+
+# See: https://docs.github.com/en/free-pro-team@latest/actions/reference/events-that-trigger-workflows
+on:
+  push:
+    paths:
+      - ".github/workflows/compile-examples.yml"
+      - "examples/**"
+      - "src/**"
+  pull_request:
+    paths:
+      - ".github/workflows/compile-examples.yml"
+      - "examples/**"
+      - "src/**"
+  schedule:
+    # Run every Tuesday at 8 AM UTC to catch breakage caused by changes to external resources (libraries, platforms).
+    - cron: "0 8 * * TUE"
+  workflow_dispatch:
+  repository_dispatch:
+
+jobs:
+  build:
+    name: ${{ matrix.board.fqbn }}
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+
+      matrix:
+        board:
+          - fqbn: arduino:avr:leonardo
+            platforms: |
+              - name: arduino:avr
+            tone: true
+          - fqbn: arduino:sam:arduino_due_x_dbg
+            platforms: |
+              - name: arduino:sam
+            # Bug report: https://github.com/arduino/ArduinoCore-sam/issues/24
+            # Change the value to true once it is fixed.
+            tone: false
+          - fqbn: arduino:samd:mkrzero
+            platforms: |
+              - name: arduino:samd
+            tone: true
+          - fqbn: arduino:samd:nano_33_iot
+            platforms: |
+              - name: arduino:samd
+            tone: true
+
+        # Make board type-specific customizations to the matrix jobs
+        include:
+          - board:
+              tone: true
+            sketch-paths: |
+              - examples/MIDIUSB_buzzer
+          - board:
+              tone: false
+            sketch-paths: ""
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Compile examples
+        uses: arduino/compile-sketches@v1
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          fqbn: ${{ matrix.board.fqbn }}
+          platforms: ${{ matrix.board.platforms }}
+          libraries: |
+            # Install the library from the local path.
+            - source-path: ./
+            # Additional library dependencies can be listed here.
+            # See: https://github.com/arduino/compile-sketches#libraries
+          sketch-paths: |
+            # Examples to compile for all boards
+            - examples/MIDIUSB_clock
+            - examples/MIDIUSB_loop
+            - examples/MIDIUSB_read
+            - examples/MIDIUSB_read
+            # Board-specific examples
+            ${{ matrix.sketch-paths }}

README.adoc

@@ -4,6 +4,7 @@
 = {repository-name} Library for Arduino =
 
 image:https://github.com/{repository-owner}/{repository-name}/actions/workflows/check-arduino.yml/badge.svg["Check Arduino status", link="https://github.com/{repository-owner}/{repository-name}/actions/workflows/check-arduino.yml"]
+image:https://github.com/{repository-owner}/{repository-name}/actions/workflows/compile-examples.yml/badge.svg["Compile Examples status", link="https://github.com/{repository-owner}/{repository-name}/actions/workflows/compile-examples.yml"]
 image:https://github.com/{repository-owner}/{repository-name}/actions/workflows/spell-check.yml/badge.svg["Spell Check status", link="https://github.com/{repository-owner}/{repository-name}/actions/workflows/spell-check.yml"]
 
 This library allows an Arduino board with USB capabilities to act as a MIDI instrument over USB. The library is based on PluggableUSB, so is only compatible with Arduino IDE 1.6.6 and newer.