coverage.yml

name: Coverage (baseline)

# Collects bun test coverage for loki-ts as a baseline. Does NOT enforce a
# threshold yet -- the artifact is uploaded for inspection. A future change
# can flip this on once we agree on a target.

on:
  push:
    branches:
      - main
      - feat/bun-migration
  pull_request:
    branches: [main]
  workflow_dispatch:

permissions:
  contents: read

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

jobs:
  bun-coverage:
    name: bun test --coverage
    runs-on: ubuntu-latest
    timeout-minutes: 10
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Setup Bun
        uses: oven-sh/setup-bun@v2
        with:
          bun-version: 1.3.13

      - name: Install loki-ts dependencies
        working-directory: loki-ts
        run: bun install

      - name: Run bun test with coverage
        working-directory: loki-ts
        run: |
          mkdir -p coverage
          set +e
          # Emit BOTH reporters: `text` prints the "All files | <pct> | ..." summary
          # to stdout (captured below into coverage.txt and parsed for the line-%
          # gate), and `lcov` writes lcov.info for the uploaded artifact. With ONLY
          # --coverage-reporter=lcov, bun writes the file but pipes no text table,
          # so the `^All files` parse found nothing and the gate failed every run
          # ("could not parse line coverage"). Both reporters keep the gate working
          # and the artifact intact.
          bun test --coverage --coverage-reporter=text --coverage-reporter=lcov --coverage-dir=./coverage 2>&1 | tee coverage/coverage.txt
          ec=${PIPESTATUS[0]}
          set -e
          if [ "$ec" -ne 0 ]; then
            echo "::error::bun test failed (exit $ec)"
            exit "$ec"
          fi

      # v7.4.10: enforce a minimum line coverage threshold. Pre-v7.4.10 this
      # workflow was baseline-only (no gate). 70% chosen from observed
      # baseline at v7.4.9; bumps later as suite matures.
      - name: Enforce minimum line coverage
        working-directory: loki-ts
        env:
          MIN_LINE_PCT: '70'
        run: |
          # Bun's real header is:
          #   File | % Funcs | % Lines | Uncovered Line #s
          # so the FIRST numeric column is % Funcs and the SECOND is % Lines.
          # This gate is named MIN_LINE_PCT and read $2, i.e. it had never once
          # measured line coverage -- verified against bun 1.3.13 on this repo:
          #   All files | 89.29 | 85.90 |      ($2=funcs, $3=lines)
          # The false-PASS direction is the dangerous one: many small functions
          # each called once scores high on % Funcs while their bodies stay
          # largely unexecuted, so the gate would wave through exactly the
          # coverage profile it exists to catch.
          #
          # The header is parsed rather than assumed, so a future column
          # reordering by bun fails loudly here instead of silently measuring
          # the wrong number again.
          COVTXT=$(sed -E 's/\x1b\[[0-9;]*m//g' coverage/coverage.txt 2>/dev/null)
          LINES_COL=$(printf '%s\n' "$COVTXT" \
            | grep -E "^File .*\|" \
            | head -1 \
            | awk -F'[|]' '{ for (i=2; i<=NF; i++) { gsub(/^[ \t]+|[ \t]+$/, "", $i); if ($i == "% Lines") { print i; exit } } }')
          if [ -z "$LINES_COL" ]; then
            echo "::error::could not locate the '% Lines' column in bun's coverage header; the table format has drifted. Failing the gate rather than measuring the wrong column."
            printf '%s\n' "$COVTXT" | head -3
            exit 1
          fi
          PCT=$(printf '%s\n' "$COVTXT" \
            | grep -E "^All files" \
            | head -1 \
            | awk -F'[|]' -v c="$LINES_COL" '{ gsub(/^[ \t]+|[ \t]+$/, "", $c); print $c }')
          if [ -z "$PCT" ]; then
            echo "::error::could not parse line coverage from bun test output; coverage format may have drifted. Failing the gate rather than silently disabling it."
            exit 1
          fi
          echo "line coverage (column $LINES_COL, '% Lines'): ${PCT}%"
          # Compare as integers (floor). awk handles float arithmetic.
          BELOW=$(awk -v p="$PCT" -v m="$MIN_LINE_PCT" 'BEGIN{ print (p+0 < m+0) ? "1" : "0" }')
          echo "Line coverage: ${PCT}% (minimum required: ${MIN_LINE_PCT}%)"
          if [ "$BELOW" = "1" ]; then
            echo "::error::line coverage ${PCT}% < threshold ${MIN_LINE_PCT}%"
            exit 1
          fi

      - name: Upload coverage artifact
        if: always()
        uses: actions/upload-artifact@v4
        with:
          name: coverage-loki-ts
          path: loki-ts/coverage/
          if-no-files-found: warn
          retention-days: 30