name: Tests

on:
  pull_request:
  push:
    branches: [main]

permissions:
  contents: read

jobs:
  test:
    name: vet + fmt + tests
    runs-on: ubuntu-24.04
    steps:
      - uses: actions/checkout@v6
        with:
          persist-credentials: false
          fetch-depth: 0
      - name: Relevant changes
        id: changes
        run: |
          if [ "$GITHUB_EVENT_NAME" = "pull_request" ]; then
            git fetch --no-tags origin "$GITHUB_BASE_REF"
            base="origin/$GITHUB_BASE_REF"
          else
            base='${{ github.event.before }}'
          fi
          if git diff --quiet "$base"...HEAD -- '*.go' go.mod go.sum Dockerfile .dockerignore .github data README.md; then
            echo "code=false" >> "$GITHUB_OUTPUT"
          else
            echo "code=true" >> "$GITHUB_OUTPUT"
          fi
      # `docker build` streams the context to the daemon. A compose bind-mount of
      # `.` mounts an empty host dir instead, because the job is itself a container.
      - name: Latest supported Go
        if: ${{ steps.changes.outputs.code == 'true' }}
        run: docker build .
      # Runs even when the step above failed, so a red build says whether the
      # failure is version-specific.
      - name: Lowest supported Go
        if: ${{ !cancelled() && steps.changes.outputs.code == 'true' }}
        run: docker build --build-arg GO_VERSION=1.22.12 .