spec: add tests for the autoUpdater on macOS that actually test if it works (#17442)

* spec: add tests for the autoUpdater on macOS that actually test if it works

* spec: add express as dep

* spec: add logic to auto-trust self-signed certificate and not run autoupdate specs on MAS

* build: fix the step name for importing the codesign cert

* chore: update updater spec PR as per feedback

* fix: s/atomBinding/electronBinding

* build: use spawn instead of exec

spec/fixtures/auto-update/update/index.js

@@ -0,0 +1,42 @@
+const fs = require('fs')
+const path = require('path')
+
+process.on('uncaughtException', (err) => {
+  console.error(err)
+  process.exit(1)
+})
+
+const { app, autoUpdater } = require('electron')
+
+autoUpdater.on('error', (err) => {
+  console.error(err)
+  process.exit(1)
+})
+
+const urlPath = path.resolve(__dirname, '../../../../url.txt')
+let feedUrl = process.argv[1]
+if (!feedUrl || !feedUrl.startsWith('http')) {
+  feedUrl = `${fs.readFileSync(urlPath, 'utf8')}/${app.getVersion()}`
+} else {
+  fs.writeFileSync(urlPath, `${feedUrl}/updated`)
+}
+
+autoUpdater.setFeedURL({
+  url: feedUrl
+})
+
+autoUpdater.checkForUpdates()
+
+autoUpdater.on('update-available', () => {
+  console.log('Update Available')
+})
+
+autoUpdater.on('update-downloaded', () => {
+  console.log('Update Downloaded')
+  autoUpdater.quitAndInstall()
+})
+
+autoUpdater.on('update-not-available', () => {
+  console.error('No update available')
+  process.exit(1)
+})