scalafmt GitHub Action

GitHub Action for checking Scala source files are correctly formatted using scalafmt.

Usage

Add a job that calls the action:

jobs:
  lint:
    steps:
      - uses: stringbean/scalafmt-action@v3
        with:
          compare-branch: main

Any scalafmt errors will then get annotated in the action results.

Minimising git fetch

You can reduce the amount of git history that is fetched by manually fetching the head and base refs:

jobs:
  lint:
    name: Scalafmt
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3

      - name: Checkout branches
        run: |
          git remote set-branches origin "${{github.base_ref}}" "${{github.head_ref}}"
          git fetch --depth 1
          git checkout "${{github.head_ref}}"

      - uses: stringbean/scalafmt-action@v3
        with:
          use-gitignore: true
          compare-branch: 'origin/${{github.base_ref}}'

Note You must include origin/ in the compare-branch if you are performing a partial fetch otherwise scalafmt will not find the branch.

Options

Name	Description	Default
version	Version of scalafmt to run with - if auto then the version in .scalafmt.conf will be used.	auto
format-files	If true then the code will be reformatted instead of checked.	false
compare-branch	Name of a branch to compare differences to. If set then only changed files will be scanned.	none
use-gitignore	Whether scalafmt should read the .gitignore file (only supported for scalafmt 2.x).	true
path	Path to Scala sources to scan.	. (repo root dir)
github-token	GitHub access token to fetch changed files using.	(autodetected)

Warning This action uses the native version of scalafmt which cannot switch versions at runtime. The version specified in the action must match the one in .scalafmt.conf or the action will fail.