VIA-227 JS Add initial benchmark

Author: james-salt4-nhs

e2e/e2e-helpers.ts

@@ -4,3 +4,17 @@ export const clickLinkAndExpectPageTitle = async (page: Page,  linkText: string,
   await page.getByRole("link", { name: linkText }).click();
   await expect(page).toHaveTitle(expectedPageTitle);
 }
+
+export const benchmark = async (page: Page, target: string) => {
+  const pageLoadTimes = [];
+  let start;
+  for (let i = 0; i < 3; i++) {
+    start = performance.now();
+    await page.goto(target);
+    await page.waitForLoadState('load');
+    pageLoadTimes.push(performance.now() - start);
+  }
+  const sumPageLoadTimes = pageLoadTimes.reduce((sum, cur) => sum + cur, 0);
+  console.log(sumPageLoadTimes);
+  return sumPageLoadTimes / pageLoadTimes.length;
+}

e2e/e2e.spec.ts

@@ -4,7 +4,7 @@ import {
   COVID_PAGE_TITLE, FLU_PAGE_TITLE, HUB_PAGE_TITLE, MENACWY_PAGE_TITLE, PNEUMO_PAGE_TITLE, RSV_PAGE_TITLE,
   SCHEDULE_PAGE_TITLE, SHINGLES_PAGE_TITLE, SIX_IN_ONE_PAGE_TITLE
 } from "./constants";
-import { clickLinkAndExpectPageTitle } from "./e2e-helpers";
+import { benchmark, clickLinkAndExpectPageTitle } from "./e2e-helpers";
 import { login } from "./User";
 
 test.describe.configure({ mode: 'serial' });
@@ -23,6 +23,11 @@ test.describe("E2E", () => {
     }
   });
 
+  test("Page Load Benchmark", async () => {
+    const bm = await(benchmark(page, "/vaccines/rsv"))
+    expect(bm).toBeLessThanOrEqual(2500);
+  });
+
   test("Back link navigation", async () => {
     await page.goto("/");