Minimal MacOS configuration

name: Minimal MacOS

on: push

jobs:
  build:
    runs-on: macos-latest
    steps:
    - name: Single step
      run: echo Hello World

    - name: Look around
      run: |
        uname -a
        pwd
        whoami
        uptime
        which perl
        which python
        which python3
        which ruby
        which node
        which java
        perl -v
        python -V
        python3 -V
        ruby -v
        node -v
        javac -version
        java -version

A sample configuration that runs on macOS (as per the runs-on field).