Github Action that tests if an yarn workspace is affected by diff with another branch. Affected means we find one file under the workspace root inside the return of git diff. A workspace A depending on another workspace B will also be affected if B is affected by changes.

name: Build affected

on:
  pull_request:
    branches: [master]

jobs:
  build:
    runs-on: ubuntu-latest
    
    steps:
      - uses: actions/checkout@v2
      
      - uses: neoxia/is-workspace-affected@v2.1.0
        id: affected
        with:
          workspace: front
          base: master
      
      - name: Build
        if: steps.affected.outputs.affected
        run: yarn workspace front run build

This will build the front workspace if it (or it's dependencies) has any difference with the version on master branch. Here we you a branch, be you can also use a tag, this will allow test on the same branch.

The pattern allow to filter the diff. If you set the following pattern '*.js' the action will search for files matching /project/workspace/*.js in the diff (here /project/workspace is the root of the workspace).
Supports any pattern supported by minimatch.