output-diffs.yaml

name: Generated output diff

on:
    push:
        branches:
            - master
    pull_request:

permissions:
    contents: read

concurrency:
    group: output-diff-${{ github.event.pull_request.number || github.sha }}
    cancel-in-progress: true

env:
    OUTPUT_SNAPSHOT_CACHE_PREFIX: quicktype-output-snapshot-v1

jobs:
    cache-master-snapshot:
        name: Cache master output snapshot
        if: github.event_name == 'push'
        runs-on: ubuntu-22.04
        steps:
            - uses: actions/checkout@v4
            - name: Restore exact snapshot
              id: snapshot-cache
              uses: actions/cache/restore@v4
              with:
                  path: .output-diffs/base
                  key: ${{ env.OUTPUT_SNAPSHOT_CACHE_PREFIX }}-${{ runner.os }}-${{ github.sha }}
            - uses: ./.github/workflows/setup
              if: steps.snapshot-cache.outputs.cache-hit != 'true'
            - name: Generate snapshot
              if: steps.snapshot-cache.outputs.cache-hit != 'true'
              env:
                  ALL_FIXTURES: "1"
                  CPUs: "4"
                  ONLY_OUTPUT: "1"
                  OUTPUT_SNAPSHOT_DIR: ${{ github.workspace }}/.output-diffs/base
              run: npm run test:output-snapshot
            - name: Save exact snapshot
              if: steps.snapshot-cache.outputs.cache-hit != 'true'
              uses: actions/cache/save@v4
              with:
                  path: .output-diffs/base
                  key: ${{ env.OUTPUT_SNAPSHOT_CACHE_PREFIX }}-${{ runner.os }}-${{ github.sha }}

    compare-pull-request:
        name: Compare generated output
        if: github.event_name == 'pull_request'
        runs-on: ubuntu-22.04
        steps:
            - name: Check out tested PR merge
              uses: actions/checkout@v4
              with:
                  ref: ${{ github.sha }}
                  path: head-source
                  fetch-depth: 2

            - name: Resolve tested base
              id: tested-base
              working-directory: head-source
              shell: bash
              run: |
                  read -ra commit <<< "$(git rev-list --parents -n 1 HEAD)"
                  if [[ "${#commit[@]}" -ne 3 ]]; then
                      echo "Expected the tested PR commit to have two parents" >&2
                      exit 1
                  fi
                  echo "sha=${commit[1]}" >> "$GITHUB_OUTPUT"

            - name: Restore exact base snapshot
              id: base-cache
              uses: actions/cache/restore@v4
              with:
                  path: .output-diffs/base
                  key: ${{ env.OUTPUT_SNAPSHOT_CACHE_PREFIX }}-${{ runner.os }}-${{ steps.tested-base.outputs.sha }}

            - name: Check out base after a cache miss
              if: steps.base-cache.outputs.cache-hit != 'true'
              uses: actions/checkout@v4
              with:
                  ref: ${{ steps.tested-base.outputs.sha }}
                  path: base-source

            - name: Check snapshot compatibility
              id: compatibility
              shell: bash
              run: |
                  if [[ "${{ steps.base-cache.outputs.cache-hit }}" == "true" ]]; then
                      echo "supported=true" >> "$GITHUB_OUTPUT"
                  elif node -e 'const p=require("./base-source/package.json"); process.exit(p.scripts?.["test:output-snapshot"] ? 0 : 1)'; then
                      echo "supported=true" >> "$GITHUB_OUTPUT"
                  else
                      echo "supported=false" >> "$GITHUB_OUTPUT"
                      echo "The base commit predates generated-output snapshot support; this bootstrap comparison is skipped." >> "$GITHUB_STEP_SUMMARY"
                  fi

            - name: Set up Node
              if: steps.compatibility.outputs.supported == 'true'
              uses: actions/setup-node@v4
              with:
                  node-version-file: head-source/.nvmrc
                  cache: npm
                  cache-dependency-path: head-source/package-lock.json

            - name: Build base after a cache miss
              id: base-build
              if: steps.compatibility.outputs.supported == 'true' && steps.base-cache.outputs.cache-hit != 'true'
              continue-on-error: true
              working-directory: base-source
              run: npm ci && npm run build

            - name: Generate base snapshot after a cache miss
              id: base-snapshot
              if: steps.compatibility.outputs.supported == 'true' && steps.base-cache.outputs.cache-hit != 'true' && steps.base-build.outcome == 'success'
              continue-on-error: true
              working-directory: base-source
              env:
                  ALL_FIXTURES: "1"
                  CPUs: "4"
                  ONLY_OUTPUT: "1"
                  OUTPUT_SNAPSHOT_DIR: ${{ github.workspace }}/.output-diffs/base
              run: npm run test:output-snapshot

            - name: Save PR-scoped base snapshot after a cache miss
              if: steps.compatibility.outputs.supported == 'true' && steps.base-cache.outputs.cache-hit != 'true' && steps.base-snapshot.outcome == 'success'
              uses: actions/cache/save@v4
              with:
                  path: .output-diffs/base
                  key: ${{ env.OUTPUT_SNAPSHOT_CACHE_PREFIX }}-${{ runner.os }}-${{ steps.tested-base.outputs.sha }}

            - name: Build tested PR merge
              if: steps.compatibility.outputs.supported == 'true' && (steps.base-cache.outputs.cache-hit == 'true' || steps.base-snapshot.outcome == 'success')
              working-directory: head-source
              run: npm ci && npm run build

            - name: Generate tested PR merge snapshot
              if: steps.compatibility.outputs.supported == 'true' && (steps.base-cache.outputs.cache-hit == 'true' || steps.base-snapshot.outcome == 'success')
              working-directory: head-source
              env:
                  ALL_FIXTURES: "1"
                  CPUs: "4"
                  ONLY_OUTPUT: "1"
                  OUTPUT_SNAPSHOT_DIR: ${{ github.workspace }}/.output-diffs/head
              run: npm run test:output-snapshot

            - name: Compare snapshots
              if: steps.compatibility.outputs.supported == 'true' && (steps.base-cache.outputs.cache-hit == 'true' || steps.base-snapshot.outcome == 'success')
              run: |
                  mkdir -p .output-diffs/result
                  head-source/node_modules/.bin/tsx head-source/script/output-diff.ts compare \
                      .output-diffs/base .output-diffs/head \
                      .output-diffs/result/result.json .output-diffs/result/output.diff

            - name: Write unavailable comparison result
              if: steps.compatibility.outputs.supported != 'true' || (steps.base-cache.outputs.cache-hit != 'true' && steps.base-snapshot.outcome != 'success')
              run: |
                  mkdir -p .output-diffs/result
                  printf '%s\n' '{"version":1,"hasDifferences":false,"files":[],"summary":{"added":0,"changedLines":0,"deleted":0,"deletions":0,"files":0,"insertions":0,"modified":0}}' > .output-diffs/result/result.json
                  : > .output-diffs/result/output.diff
                  echo "The base commit could not generate an output snapshot, so this comparison is unavailable." >> "$GITHUB_STEP_SUMMARY"

            - name: Write comparison metadata
              env:
                  BASE_SHA: ${{ steps.tested-base.outputs.sha }}
                  HEAD_SHA: ${{ github.event.pull_request.head.sha }}
                  PR_NUMBER: ${{ github.event.pull_request.number }}
                  PR_SHA: ${{ github.sha }}
                  PR_URL: ${{ github.event.pull_request.html_url }}
                  SUPPORTED: ${{ steps.compatibility.outputs.supported == 'true' && (steps.base-cache.outputs.cache-hit == 'true' || steps.base-snapshot.outcome == 'success') }}
              run: |
                  node - <<'NODE'
                  const fs = require("node:fs");
                  const metadata = {
                      baseSha: process.env.BASE_SHA,
                      headSha: process.env.HEAD_SHA,
                      prNumber: Number(process.env.PR_NUMBER),
                      prSha: process.env.PR_SHA,
                      prUrl: process.env.PR_URL,
                      supported: process.env.SUPPORTED === "true",
                  };
                  fs.writeFileSync(".output-diffs/result/metadata.json", `${JSON.stringify(metadata, null, 2)}\n`);
                  NODE

            - name: Summarize comparison
              run: |
                  node - <<'NODE'
                  const fs = require("node:fs");
                  const result = JSON.parse(fs.readFileSync(".output-diffs/result/result.json", "utf8"));
                  const s = result.summary;
                  fs.appendFileSync(process.env.GITHUB_STEP_SUMMARY,
                      result.hasDifferences
                          ? `Generated output differs in **${s.files} files** (${s.modified} modified, ${s.added} new, ${s.deleted} deleted), with **${s.changedLines} changed lines** (+${s.insertions}/-${s.deletions}).\n`
                          : "Generated output is unchanged.\n");
                  NODE

            - name: Upload comparison data
              uses: actions/upload-artifact@v4
              with:
                  name: generated-output-diff
                  path: .output-diffs/result
                  if-no-files-found: error
                  retention-days: 14