coverage-trend.yml

name: Check coverage trend on Codecov
on:
  workflow_call:
    secrets:
      CODECOV_GET_TOKEN:
        description: 'The token to query the codecov API.'
        required: true
    outputs:
      should_notify:
        description: 'Returns true if the coverage has changed.'
        value: ${{ jobs.check-coverage.outputs.should_notify }}
      msg:
        description: 'The message describing the change. Suitable to post on Slack.'
        value: ${{ jobs.check-coverage.outputs.msg }}

jobs:
  check-coverage:
    runs-on: ubuntu-latest
    outputs:
      msg: ${{ steps.make_msg.outputs.msg }}
      should_notify: ${{ steps.get_coverage.outputs.should_notify }}
    steps:
      # Downloads the artifact from the most recent successful run
      - name: Download commit sha of the most recent successful run
        continue-on-error: true
        uses: dawidd6/action-download-artifact@v6
        with:
          name: head-sha.txt
          if_no_artifact_found: ignore
      - name: Get today's and last run's coverage trends from codecov
        id: get_coverage
        # API reference: https://docs.codecov.com/reference/repos_totals_retrieve
        run: |
          # Get the previous commit coverage, if the last sha is available
          if [ ! -f head-sha.txt ]
          then
            echo "No previous coverage found."

            # Update the head-sha.txt file with the current sha,
            # so next time we campare against the current coverage.
            echo ${{ github.sha }} > head-sha.txt

            echo "should_notify=false"  >> "$GITHUB_OUTPUT"
            exit 0
          fi

          PREV_SHA=$( cat head-sha.txt )
          echo "Previous sha: \"$PREV_SHA\""

          # Check if the sha has changed
          if [ "$PREV_SHA" == "${{ github.sha }}" ]
          then
            echo "No new commits since last run."
            echo "should_notify=false"  >> "$GITHUB_OUTPUT"
            exit 0
          fi

          # Query the previous coverage from codecov
          curl --request GET \
            --url "https://api.codecov.io/api/v2/github/${{ github.repository_owner }}/repos/${{ github.event.repository.name }}/totals/?sha=$PREV_SHA" \
            --header 'accept: application/json' \
            --header "authorization: Bearer ${{ secrets.CODECOV_GET_TOKEN }}" \
            > coverage-prev.json
          cat coverage-prev.json | jq ".totals.coverage" > coverage-prev.txt
          echo "Previous coverage query result:"
          cat coverage-prev.json | jq "del(.files)"
          echo

          # Query the current coverage from codecov
          curl --request GET \
            --url "https://api.codecov.io/api/v2/github/${{ github.repository_owner }}/repos/${{ github.event.repository.name }}/totals/?sha=${{ github.sha }}" \
            --header 'accept: application/json' \
            --header "authorization: Bearer ${{ secrets.CODECOV_GET_TOKEN }}" \
            > coverage.json
          cat coverage.json | jq ".totals.coverage" > coverage.txt
          echo "Current coverage query result:"
          cat coverage.json | jq "del(.files)"
          echo

          echo
          echo "Previous coverage: `cat coverage-prev.txt`%"
          echo "Current coverage: `cat coverage.txt`%"

          # A `null` in either coverage means that the coverage is not available,
          # so we don't want to notify about that.
          if [ "$( cat coverage-prev.txt )" == "null" ]
          then
            echo "Previous coverage not available."
            echo ${{ github.sha }} > head-sha.txt
            echo "should_notify=false"  >> "$GITHUB_OUTPUT"
            exit 0
          fi
          if [ "$( cat coverage.txt )" == "null" ]
          then
            echo "Current coverage not available."
            # Note that we don't update the head-sha.txt file here,
            # so next time we compare against the one that had coverage data.
            echo "should_notify=false"  >> "$GITHUB_OUTPUT"
            exit 0
          fi

          echo ${{ github.sha }} > head-sha.txt
          echo "should_notify=true"  >> "$GITHUB_OUTPUT"
      - name: Compare with previous summary and make message
        id: make_msg
        if: steps.get_coverage.outputs.should_notify == 'true'
        run: |
          prev=`cat coverage-prev.txt`
          current=`cat coverage.txt`
          change=`printf "%.2f%% --> %.2f%%" $prev $current`
          codecov="https://codecov.io/gh/${{ github.repository }}?search=&trend=7%20days"
          if (( $(echo "$prev < $current + 0.04" | bc -l) ))
          then
            MSG="msg=Coverage check for ${{ github.repository }} shows no regression (${change}). ✅ ${codecov}"
          else
            MSG="msg=Coverage check for ${{ github.repository }} shows regression (${change}). ❌ ${codecov}"
          fi
          echo $MSG
          echo $MSG  >> "$GITHUB_OUTPUT"
      - name: Upload current HEAD sha
        uses: actions/upload-artifact@v4
        with:
          name: head-sha.txt
          path: head-sha.txt