GitHub action for running tests

[charpov]

This setup is working well for me, so I thought I'd post it here. (The documentation describes actions for publishing but does not mention caching Coursier, which can avoid a ton of downloads. Note that the Coursier cache also caches ~/.cache/mill by default.)

name: Test

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

jobs:
  tests:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v6
    - uses: coursier/cache-action@v8
    
    - name: Run tests
      run: ./mill S.test + T.test

[lihaoyi]

Simplest thing to do would be ./mill __.test, unless you only want to run specific suites in which case listing them out separated by + as you did would be necessary