Building a scheduled CI E2E test failure Slack notifier

March 24, 2021

How to build a Slack notifier when scheduled E2E tests fail.


At one of my jobs, we needed to build out an E2E test suite. We settled on Microsoft's Playwright along with playwright-test and folio as the test runner.

These E2E tests serve to ensure that our React and Next.JS front end worked as expected with the corresponding GraphQL and Rest endpoints across our various environments.

Our end goal is a Slack channel titled

that gets messages we send from a Slack API Webhook that look like the following (Testing against is the URL of the environment we are testing against, redacted for work).

A Slack message showing which E2E tests failed, what CI job they failed on, the total time, and the error count.

Building it

I wanted to build it using a minimal amount of dependencies. playwright-test gives us the option to export a junit report of what tests fail.

The entire

might look like the following

  "name": "e2e",
  "version": "1.0.0",
  "main": "index.js",
  "private": true,
  "scripts": {
    "test": "npx folio --timeout=120000 --param browserName=firefox --param screenshotOnFailure",
    "test:h": "yarn test --param video --param headful",
    "test:v": "yarn test --param video"
  "dependencies": {
    "@playwright/test": "^0.192.0",
    "dotenv": "^8.2.0",
    "playwright": "^1.9.2",
    "playwright-core": "^1.9.2",
    "typescript": "^4.1.3",
    "xml2js": "^0.4.23"

The nice thing here is we already utilize the junit report (supported out of the box with playwright-test) to pass to Gitlab CI to get reporting of specific test failures inside our merge requests.

In CI we tag on the junit reporter like so.

yarn run test --reporter=junit,line

We would then call the notification script

node notification.js

The contents of


const https = require("https"),
  fs = require("fs"),
  xml2js = require("xml2js"),
  parser = new xml2js.Parser();

async function msgBuilder() {
  const contents = fs.readFileSync(__dirname + "/junit.xml", "utf8");
  const {
    testsuites: {
      $: { name, tests, failures, errors, time },
  } = await parser.parseStringPromise(contents);
  const failedSuites = testsuite.filter(({ $: { failures } }) => failures > 0);
  if (failedSuites.length === 0) {
  let msg = `
Total Time: ${time}s
Tests / Failures / Errors: ${tests}, ${failures}, ${errors}
Testing against: ${process.env.FRONTEND_URL}
Gitlab Job: <${process.env.CI_JOB_URL}|${process.env.CI_JOB_ID}>
> Failures:`;
  failedSuites.forEach(({ $: { name }, testcase }) => {
    const failures = testcase.filter((tc) => tc.failure);
    if (failures) {
        ({ $: { name } }) =>
          (msg = `${msg}
>     ${name}`)
  return msg;

async function notifier() {
  const msg = await msgBuilder();
  if (msg) {
    const data = JSON.stringify({
      text: msg,
    const options = {
      host: "",
      path: "/services/THIS/IS/FAKE",
      port: 443,
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        "Content-Length": data.length,

    const req = https.request(options, (res) => {
      console.log(`statusCode: ${res.statusCode}`);

      res.on("data", (d) => {

    req.on("error", (error) => {