Add language-agnostic emitter-diff tool + python adapter #6
Workflow file for this run
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| name: "python / emitter diff" | |
| # Generates code with the current checkout's emitter and with the PR's base | |
| # commit, then diffs the two. The rendered HTML diff is uploaded as a per-PR | |
| # artifact, and a sticky PR comment summarizes the changed files (+/-) with a | |
| # link to download it, so reviewers can see exactly how an emitter change | |
| # affects generated SDKs. Powered by the language-agnostic eng/emitter-diff tool. | |
| # | |
| # Python's generator uses a native two-phase pipeline (TypeSpec emits YAML, then | |
| # a batched Python subprocess writes the .py files) with a venv co-located with | |
| # each emitter version. So this workflow builds + sets up a venv for both the | |
| # head checkout and a worktree of the baseline commit before diffing. | |
| on: | |
| pull_request: | |
| branches: | |
| - main | |
| - release/* | |
| paths: | |
| - "packages/http-client-python/**" | |
| - "eng/emitter-diff/**" | |
| - ".github/workflows/ci-emitter-diff-python.yml" | |
| workflow_dispatch: | |
| inputs: | |
| baseline: | |
| description: "Baseline emitter ref (npm version, local path, or github ref). Defaults to the approved baseline SHA file." | |
| required: false | |
| default: "" | |
| permissions: | |
| contents: read | |
| pull-requests: write | |
| concurrency: | |
| group: ${{ github.workflow }}-${{ github.ref }} | |
| cancel-in-progress: true | |
| jobs: | |
| emitter-diff: | |
| name: "Generate & Diff" | |
| runs-on: ubuntu-latest | |
| steps: | |
| - uses: actions/checkout@v6 | |
| with: | |
| fetch-depth: 0 | |
| - uses: ./.github/actions/setup | |
| - uses: actions/setup-python@v5 | |
| with: | |
| python-version: "3.12" | |
| - name: Install repo dependencies (emitter-diff tool) | |
| run: pnpm install | |
| - name: Build + venv for head emitter | |
| working-directory: packages/http-client-python | |
| run: | | |
| npm ci | |
| npm run build | |
| npm run install | |
| - name: Determine baseline | |
| id: baseline | |
| run: | | |
| input="${{ github.event.inputs.baseline }}" | |
| if [ -z "$input" ]; then | |
| sha_file="eng/emitter-diff/baselines/python.sha" | |
| base_sha="$(grep -vE '^[[:space:]]*(#|$)' "$sha_file" | head -n1 | tr -d '[:space:]')" | |
| if [ -z "$base_sha" ]; then | |
| echo "::error::No approved baseline SHA found in $sha_file" | |
| exit 1 | |
| fi | |
| echo "Approved baseline SHA: $base_sha (from $sha_file)" | |
| git worktree add "${{ runner.temp }}/baseline" "$base_sha" | |
| (cd "${{ runner.temp }}/baseline/packages/http-client-python" && npm ci && npm run build && npm run install) | |
| input="local:${{ runner.temp }}/baseline/packages/http-client-python" | |
| echo "sha=$base_sha" >> "$GITHUB_OUTPUT" | |
| fi | |
| echo "ref=$input" >> "$GITHUB_OUTPUT" | |
| echo "Baseline: $input" | |
| - name: Run emitter diff | |
| id: diff | |
| run: | | |
| set +e | |
| pnpm --filter @typespec/emitter-diff exec tsx src/cli.ts \ | |
| --emitter python \ | |
| --baseline "${{ steps.baseline.outputs.ref }}" \ | |
| --work-dir "${{ runner.temp }}/emitter-diff" \ | |
| --html "${{ runner.temp }}/emitter-diff.html" \ | |
| --patch "${{ runner.temp }}/emitter-diff.patch" \ | |
| --fail-on-diff \ | |
| | tee "${{ runner.temp }}/emitter-diff.log" | |
| echo "status=${PIPESTATUS[0]}" >> "$GITHUB_OUTPUT" | |
| - name: Write job summary | |
| if: always() | |
| run: | | |
| { | |
| echo "## Emitter diff" | |
| echo "" | |
| echo "Baseline (approved): \`${{ steps.baseline.outputs.sha }}\` vs current checkout." | |
| echo "" | |
| if [ "${{ steps.diff.outputs.status }}" = "2" ]; then | |
| echo "❌ **Generated output changed vs the approved baseline.**" | |
| echo "" | |
| echo "If this change is intended, approve it by updating" | |
| echo "\`eng/emitter-diff/baselines/python.sha\` to a commit on your branch that" | |
| echo "contains your emitter changes, then push." | |
| elif [ "${{ steps.diff.outputs.status }}" = "0" ]; then | |
| echo "✅ Generated output matches the approved baseline." | |
| fi | |
| echo "" | |
| echo '```' | |
| grep -E "Diff summary:" "${{ runner.temp }}/emitter-diff.log" || echo "No summary captured." | |
| echo '```' | |
| echo "" | |
| echo "Download the **emitter-diff-html** artifact for the full rendered diff." | |
| } >> "$GITHUB_STEP_SUMMARY" | |
| - name: Upload HTML diff | |
| if: always() | |
| uses: actions/upload-artifact@v7 | |
| with: | |
| name: emitter-diff-html | |
| path: ${{ runner.temp }}/emitter-diff.html | |
| if-no-files-found: ignore | |
| retention-days: 7 | |
| - name: Comment on PR | |
| if: always() && github.event_name == 'pull_request' | |
| continue-on-error: true | |
| uses: actions/github-script@v7 | |
| env: | |
| BASELINE: ${{ steps.baseline.outputs.sha }} | |
| PATCH_FILE: ${{ runner.temp }}/emitter-diff.patch | |
| HTML_FILE: ${{ runner.temp }}/emitter-diff.html | |
| with: | |
| script: | | |
| const fs = require("fs"); | |
| const marker = "<!-- emitter-diff-python -->"; | |
| const runUrl = `${context.serverUrl}/${context.repo.owner}/${context.repo.repo}/actions/runs/${context.runId}`; | |
| // Parse the unified patch directly so the numbers match the tool exactly. | |
| let patch = ""; | |
| try { patch = fs.readFileSync(process.env.PATCH_FILE, "utf8"); } catch {} | |
| const lines = patch.split("\n"); | |
| const files = []; | |
| let insertions = 0, deletions = 0; | |
| for (const line of lines) { | |
| const m = line.match(/^diff --git a\/(.+?) b\/(.+)$/); | |
| if (m) files.push(m[2]); | |
| else if (line.startsWith("+") && !line.startsWith("+++")) insertions++; | |
| else if (line.startsWith("-") && !line.startsWith("---")) deletions++; | |
| } | |
| const hasChanges = patch.trim().length > 0; | |
| const htmlExists = fs.existsSync(process.env.HTML_FILE); | |
| let body = `${marker}\n## 🐍 Python emitter diff\n\n` + | |
| `Approved baseline \`${process.env.BASELINE}\` vs this PR's checkout.\n\n`; | |
| if (!hasChanges) { | |
| body += `✅ **No changes** — generated output matches the approved baseline.\n`; | |
| } else { | |
| body += `❌ **${files.length} file(s) changed** · +${insertions} / -${deletions}\n\n`; | |
| const shown = files.slice(0, 50); | |
| body += `<details><summary>Changed files</summary>\n\n` + | |
| shown.map((f) => `- \`${f}\``).join("\n") + | |
| (files.length > shown.length ? `\n- …and ${files.length - shown.length} more` : "") + | |
| `\n</details>\n\n`; | |
| if (htmlExists) { | |
| body += `📄 Download the **emitter-diff-html** artifact from the ` + | |
| `[workflow run](${runUrl}) for the full side-by-side rendered diff.\n\n`; | |
| } | |
| body += `**This check fails until the change is approved.** If the new output is ` + | |
| `intended, update \`eng/emitter-diff/baselines/python.sha\` to a commit on this ` + | |
| `branch that contains your emitter changes, then push.\n`; | |
| } | |
| body += `\n_Generated by \`eng/emitter-diff\`._`; | |
| const { owner, repo } = context.repo; | |
| const issue_number = context.issue.number; | |
| const { data: comments } = await github.rest.issues.listComments({ owner, repo, issue_number }); | |
| const existing = comments.find((c) => c.body && c.body.includes(marker)); | |
| if (existing) { | |
| await github.rest.issues.updateComment({ owner, repo, comment_id: existing.id, body }); | |
| } else { | |
| await github.rest.issues.createComment({ owner, repo, issue_number, body }); | |
| } | |
| - name: Enforce baseline approval | |
| if: always() | |
| run: | | |
| status="${{ steps.diff.outputs.status }}" | |
| if [ "$status" = "2" ]; then | |
| echo "::error::Generated output differs from the approved baseline (${{ steps.baseline.outputs.sha }})." | |
| echo "Review the emitter-diff-html artifact. If the change is intended, approve it by" | |
| echo "updating eng/emitter-diff/baselines/python.sha to a commit on your branch that" | |
| echo "contains your emitter changes, then push." | |
| exit 1 | |
| elif [ "$status" != "0" ]; then | |
| echo "::error::emitter-diff failed (exit $status). See the log and artifact." | |
| exit 1 | |
| fi | |
| echo "Generated output matches the approved baseline." |