feat(lighthouse): surface scores on every PR

Adding new deno script that surface lighthouse results
on every PR. On pushes to main, update issue #4584:
#4584

- Add TS types for the Github API & Lighthouse
- Run workflow on pull_request "opened" & "synchronize"
- `includePassedAssertions` to get passed checks

Co-authored-by: Joshua <[email protected]>
Co-authored-by: Pete Faulconbridge <[email protected]>

.github/workflows/lighthouse.yml

@@ -1,25 +1,41 @@
 name: DCR Run Lighthouse CI
 on:
-    push:
-        paths-ignore:
-            - "apps-rendering/**"
+  push:
+    branches:
+      - main
+    paths-ignore:
+      - "apps-rendering/**"
+  pull_request:
+    #  If/when we compare results to `main`, we should also run on 'reopened'
+    types: [opened, synchronize]
+
 jobs:
-    lhci:
-        name: DCR Lighthouse
-        runs-on: ubuntu-latest
-        steps:
-            - name: Checkout code
-              uses: actions/checkout@v3
-            - name: Install Node
-              uses: guardian/actions-setup-node@main
-            # Make sure we install dependencies in the root directory
-            - uses: bahmutov/npm-install@v1
-            - run: make build
-              working-directory: dotcom-rendering
-            - name: Install and run Lighthouse CI
-              working-directory: dotcom-rendering
-              env:
-                  LHCI_GITHUB_TOKEN: ${{ secrets.LHCI_GITHUB_TOKEN }}
-              run: |
-                  npm install -g [email protected] @lhci/[email protected]
-                  lhci autorun
+  lhci:
+    name: DCR Lighthouse
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+      - name: Install Node
+        uses: guardian/actions-setup-node@main
+      # Make sure we install dependencies in the root directory
+      - uses: bahmutov/npm-install@v1
+      - run: make build
+        working-directory: dotcom-rendering
+      - name: Install and run Lighthouse CI
+        working-directory: dotcom-rendering
+        env:
+          LHCI_GITHUB_TOKEN: ${{ secrets.LHCI_GITHUB_TOKEN }}
+        run: |
+          npm install -g [email protected] @lhci/[email protected]
+          lhci autorun
+
+      - name: Setup deno
+        uses: denolib/setup-deno@v2
+        with:
+          deno-version: v1.21.0
+
+      - name: Surface Lighthouse Results
+        run: deno run --no-check --allow-net=api.github.com --allow-env="GITHUB_TOKEN","GITHUB_EVENT_PATH" --allow-read scripts/deno/surface-lighthouse-results.ts
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.gitignore

@@ -44,3 +44,6 @@ coverage
 
 # Architecture Diagram
 webArchitecture.svg
+
+# lighthouse results from local build
+.lighthouseci/

dotcom-rendering/lighthouserc.js

@@ -10,13 +10,14 @@ module.exports = {
       puppeteerScript: './scripts/lighthouse/puppeteer-script.js',
       settings: {
         onlyCategories: "accessibility,best-practices,performance,seo",
-        disableStorageReset: true
+        disableStorageReset: true,
       }
     },
     upload: {
       target: 'temporary-public-storage',
     },
     assert: {
+      includePassedAssertions: true,
       assertions: {
         "first-contentful-paint": ["warn", {"maxNumericValue": 1500}],
         "largest-contentful-paint": ["warn", {"maxNumericValue": 3000}],

scripts/deno/surface-lighthouse-results.ts

@@ -0,0 +1,208 @@
+import { Octokit } from "https://cdn.skypack.dev/octokit";
+import type { RestEndpointMethodTypes } from "https://cdn.skypack.dev/@octokit/plugin-rest-endpoint-methods?dts";
+import type { EventPayloadMap } from "https://cdn.skypack.dev/@octokit/webhooks-types?dts";
+import "https://raw.githubusercontent.com/GoogleChrome/lighthouse-ci/v0.8.2/types/assert.d.ts";
+
+/* -- Setup -- */
+
+type OctokitWithRest = {
+	rest: {
+		issues: {
+			[Method in keyof RestEndpointMethodTypes["issues"]]: (
+				arg: RestEndpointMethodTypes["issues"][Method]["parameters"]
+			) => Promise<RestEndpointMethodTypes["issues"][Method]["response"]>;
+		};
+	};
+};
+
+/** Github token for Authentication */
+const token = Deno.env.get("GITHUB_TOKEN");
+if (!token) throw new Error("Missing GITHUB_TOKEN");
+
+/** Path for workflow event */
+const path = Deno.env.get("GITHUB_EVENT_PATH");
+if (!path) throw new Error("Missing GITHUB_EVENT_PATH");
+
+/**
+ * https://docs.github.com/en/developers/webhooks-and-events/webhooks/webhook-events-and-payloads
+ */
+const payload: EventPayloadMap["push" | "pull_request"] = JSON.parse(
+	Deno.readTextFileSync(path)
+);
+
+const isPullRequestEvent = (
+	payload: EventPayloadMap[keyof EventPayloadMap]
+): payload is EventPayloadMap["pull_request"] =>
+	//@ts-expect-error -- We’re actually checking the type
+	typeof payload?.pull_request?.number === "number";
+
+/**
+ * One of two values depending on the workflow trigger event
+ *
+ * - on a "pull_request" event: the current Issue / PR number
+ * on which to add or update the Lighthouse report
+ *
+ * - on a "push" event: the original issue to track the latest report:
+ * https://github.com/guardian/dotcom-rendering/issues/4584, which allows
+ * to track the state Lighthouse CI Reports on `main` over time.
+ */
+const issue_number = isPullRequestEvent(payload)
+	? // If PullRequestEvent
+	  payload.pull_request.number
+	: // If PushEvent
+	  4584;
+
+console.log(`Using issue #${issue_number}`);
+
+/** The Lighthouse results directory  */
+const dir = "dotcom-rendering/.lighthouseci";
+
+const links: Record<string, string> = JSON.parse(
+	Deno.readTextFileSync(`${dir}/links.json`)
+);
+
+/** https://github.com/GoogleChrome/lighthouse-ci/blob/5963dcce0e88b8d3aedaba56a93ec4b93cf073a1/packages/utils/src/assertions.js#L15-L30 */
+interface AssertionResult {
+	url: string;
+	name:
+		| keyof Omit<LHCI.AssertCommand.AssertionOptions, "aggregationMethod">
+		| "auditRan";
+	operator: string;
+	expected: number;
+	actual: number;
+	values: number[];
+	passed: boolean;
+	level?: LHCI.AssertCommand.AssertionFailureLevel;
+	auditId?: string;
+	auditProperty?: string;
+	auditTitle?: string;
+	auditDocumentationLink?: string;
+	message?: string;
+}
+const results: AssertionResult[] = JSON.parse(
+	Deno.readTextFileSync(`${dir}/assertion-results.json`)
+);
+
+/* -- Definitions -- */
+
+/** The string to search for when looking for a comment */
+const REPORT_TITLE = "⚡️ Lighthouse report";
+const GIHUB_PARAMS = {
+	owner: "guardian",
+	repo: "dotcom-rendering",
+	issue_number,
+} as const;
+
+// @ts-expect-error -- Octokit’s own types are not as good as ours
+const octokit = new Octokit({ auth: token }) as OctokitWithRest;
+
+/* -- Methods -- */
+
+/** If large number, round to 0 decimal, if small, round to 6 decimal points */
+const formatNumber = (expected: number, actual: number): string =>
+	expected > 100 ? Math.ceil(actual).toString() : actual.toFixed(6);
+
+const getStatus = (
+	passed: boolean,
+	level: AssertionResult["level"]
+): "✅" | "⚠️" | "❌" => {
+	if (passed) return "✅";
+
+	switch (level) {
+		case "off":
+		case "warn":
+			return "⚠️";
+		case "error":
+		default:
+			return "❌";
+	}
+};
+
+const generateAuditTable = (
+	auditUrl: string,
+	results: AssertionResult[]
+): string => {
+	const reportUrl = links[auditUrl];
+
+	const resultsTemplateString = results.map(
+		({ auditTitle, auditProperty, passed, expected, actual, level }) =>
+			`| ${auditTitle ?? auditProperty ?? "Unknown Test"} | ${getStatus(
+				passed,
+				level
+			)} | ${expected} | ${formatNumber(expected, actual)} |`
+	);
+
+	const [endpoint, testUrlClean] = auditUrl.split("?url=");
+
+	const table = [
+		`### [Report for ${endpoint.split("/").slice(-1)}](${reportUrl})`,
+		`> tested url \`${testUrlClean}\``,
+		"",
+		"| Category | Status | Expected | Actual |",
+		"| --- | --- | --- | --- |",
+		...resultsTemplateString,
+		"",
+	].join("\n");
+
+	return table;
+};
+
+const createLighthouseResultsMd = (): string => {
+	const auditCount = results.length;
+	const failedAuditCount = results.filter((result) => !result.passed).length;
+	const auditUrls = [...new Set<string>(results.map((result) => result.url))];
+
+	return [
+		`## ${REPORT_TITLE} for the changes in this PR`,
+		`Lighthouse tested ${auditUrls.length} URLs  `,
+		failedAuditCount > 0
+			? `⚠️ Budget exceeded for ${failedAuditCount} of ${auditCount} audits.`
+			: "All audits passed",
+		...auditUrls.map((url) =>
+			generateAuditTable(
+				url,
+				results.filter((result) => result.url === url)
+			)
+		),
+	].join("\n\n");
+};
+
+const getCommentID = async (): Promise<number | null> => {
+	const { data: comments } = await octokit.rest.issues.listComments({
+		...GIHUB_PARAMS,
+	});
+
+	const comment = comments.find((comment) =>
+		comment.body?.includes(REPORT_TITLE)
+	);
+
+	return comment?.id ?? null;
+};
+
+try {
+	const body = createLighthouseResultsMd();
+	const comment_id = await getCommentID();
+
+	const { data } = comment_id
+		? await octokit.rest.issues.updateComment({
+				...GIHUB_PARAMS,
+				comment_id,
+				body,
+		  })
+		: await octokit.rest.issues.createComment({
+				...GIHUB_PARAMS,
+				body,
+		  });
+
+	console.log(
+		`Successfully ${
+			comment_id ? "updated" : "created"
+		} Lighthouse report comment`
+	);
+	console.log("See:", data.html_url);
+} catch (error) {
+	if (error instanceof Error) throw error;
+
+	console.error("there was an error:", error.message);
+	Deno.exit(1);
+}