code-cover-gen.yaml

name: PR code coverage (generate)

on:
  # This workflow does not have access to secrets because it runs on top of
  # potentially unsafe changes.
  pull_request:
    types: [ opened, reopened, synchronize ]
    branches: [ master ]

jobs:
  # The results of this job are uploaded as artifacts. A separate job will
  # download the artifacts and upload them to a GCS bucket.
  code-cover-gen:
    runs-on: ubuntu-latest
    env:
      PR: ${{ github.event.pull_request.number }}
      HEAD_SHA: ${{ github.event.pull_request.head.sha }}
    steps:
      - uses: actions/checkout@v3
        with:
          # By default, checkout merges the PR into the current master.
          # Instead, we want to check out the PR as-is.
          ref: ${{ github.event.pull_request.head.sha }}
          # Fetch all branches and history (we'll need the origin/master ref and
          # the base commit).
          fetch-depth: 0

      - name: Set up Go
        uses: actions/setup-go@v2
        with:
          go-version: "1.20"

      - name: Generate "after" coverage
        shell: bash
        run: |
          set -e
          mkdir -p artifacts
          make testcoverage COVER_PROFILE=artifacts/cover-after.out
          go run github.com/cockroachdb/code-cov-utils/gocover2json@latest \
            --trim-prefix github.com/cockroachdb/pebble/ \
            artifacts/cover-after.out artifacts/cover-${PR}-${HEAD_SHA}.json

      # Running the "before" coverage for each PR (rather than in a job that
      # runs on push) is a little odd, but it allows restricting the packages on
      # a per-PR basis (if it becomes necessary in the future).
      - name: Generate "before" coverage
        shell: bash
        run: |
          set -e
          # Note that github.event.pull_request.base.sha is not what we want -
          # it is the current master tip, not the commit this PR is actually
          # based on.
          BASE_SHA=$(git merge-base origin/master ${HEAD_SHA})
          git checkout -f ${BASE_SHA}
          make testcoverage COVER_PROFILE=artifacts/cover-before.out
          SHA=$(git rev-parse HEAD)
          go run github.com/cockroachdb/code-cov-utils/gocover2json@latest \
            --trim-prefix github.com/cockroachdb/pebble/ \
            artifacts/cover-before.out artifacts/cover-${PR}-${BASE_SHA}.json

      - name: Upload artifacts
        uses: actions/upload-artifact@v2
        with:
          name: cover
          path: artifacts/cover-*.json