fix: suppress EventEmitter warnings + other Node warnings in prod (#15723)

packages/server/index.js

@@ -34,7 +34,7 @@ process.noDeprecation = process.env.CYPRESS_INTERNAL_ENV === 'production'
 // always show stack traces for Electron deprecation warnings
 process.traceDeprecation = true
 
-require('./lib/util/suppress_unauthorized_warning').suppress()
+require('./lib/util/suppress_warnings').suppress()
 
 function launchOrFork () {
   const nodeOptions = require('./lib/util/node_options')

packages/server/lib/browsers/electron.js

@@ -235,7 +235,7 @@ module.exports = {
       return this._enableDebugger(win.webContents)
     })
     .then(() => {
-      return this._handleDownloads(win.webContents, options.downloadsFolder, automation)
+      return this._handleDownloads(win, options.downloadsFolder, automation)
     })
     .return(win)
   },
@@ -291,8 +291,8 @@ module.exports = {
     return webContents.debugger.sendCommand('Console.enable')
   },
 
-  _handleDownloads (webContents, dir, automation) {
-    webContents.session.on('will-download', (event, downloadItem) => {
+  _handleDownloads (win, dir, automation) {
+    const onWillDownload = (event, downloadItem) => {
       const savePath = path.join(dir, downloadItem.getFilename())
 
       automation.push('create:download', {
@@ -307,9 +307,16 @@ module.exports = {
           id: downloadItem.getETag(),
         })
       })
-    })
+    }
 
-    return webContents.debugger.sendCommand('Page.setDownloadBehavior', {
+    const { session } = win.webContents
+
+    session.on('will-download', onWillDownload)
+
+    // avoid adding redundant `will-download` handlers if session is reused for next spec
+    win.on('closed', () => session.removeListener('will-download', onWillDownload))
+
+    return win.webContents.debugger.sendCommand('Page.setDownloadBehavior', {
       behavior: 'allow',
       downloadPath: dir,
     })

packages/server/lib/plugins/child/index.js

@@ -1,6 +1,6 @@
 require('graceful-fs').gracefulify(require('fs'))
 
-require('../../util/suppress_unauthorized_warning').suppress()
+require('../../util/suppress_warnings').suppress()
 
 const ipc = require('../util').wrapIpc(process)
 const { file: pluginsFile, projectRoot } = require('minimist')(process.argv.slice(2))

packages/server/lib/plugins/util.js

@@ -19,6 +19,10 @@ module.exports = {
       return emitter.emit(message.event, ...message.args)
     })
 
+    // prevent max listeners warning on ipc
+    // @see https://github.com/cypress-io/cypress/issues/1305#issuecomment-780895569
+    emitter.setMaxListeners(Infinity)
+
     return {
       send (event, ...args) {
         if (aProcess.killed) {

packages/server/lib/util/suppress_warnings.js

@@ -1,6 +1,7 @@
 const _ = require('lodash')
+const Debug = require('debug')
 
-const originalEmitWarning = process.emitWarning
+const debug = Debug('cypress:server:lib:util:suppress_warnings')
 
 let suppressed = false
 
@@ -10,7 +11,8 @@ let suppressed = false
  * https://github.com/cypress-io/cypress/issues/5248
  */
 const suppress = () => {
-  if (suppressed) {
+  if (suppressed || process.env.CYPRESS_INTERNAL_ENV === 'production') {
+    // in development, still log warnings since they are helpful
     return
   }
 
@@ -18,7 +20,7 @@ const suppress = () => {
 
   process.emitWarning = (warning, type, code, ...args) => {
     if (_.isString(warning) && _.includes(warning, 'NODE_TLS_REJECT_UNAUTHORIZED')) {
-      // https://github.com/nodejs/node/blob/82f89ec8c1554964f5029fab1cf0f4fad1fa55a8/lib/_tls_wrap.js#L1378-L1384
+      // https://github.com/nodejs/node/blob/85e6089c4db4da23dd88358fe0a12edefcd411f2/lib/internal/options.js#L17
 
       return
     }
@@ -31,7 +33,7 @@ const suppress = () => {
       return
     }
 
-    return originalEmitWarning.call(process, warning, type, code, ...args)
+    debug('suppressed emitWarning from node: %o', { process, warning, type, code, args })
   }
 }
 

packages/server/test/e2e/0_max_listeners_spec.ts

@@ -0,0 +1,33 @@
+import _ from 'lodash'
+import path from 'path'
+import fs from 'fs-extra'
+
+import e2e from '../support/helpers/e2e'
+import Fixtures from '../support/helpers/fixtures'
+
+const projectPath = Fixtures.projectPath('max-listeners')
+
+describe('max listeners warning spec', () => {
+  e2e.setup()
+
+  // @see https://github.com/cypress-io/cypress/issues/1305
+  e2e.it('does not log MaxEventListeners error', {
+    browser: 'electron',
+    project: projectPath,
+    spec: '*',
+    onRun: async (exec) => {
+      const integrationPath = path.join(projectPath, 'cypress/integration')
+
+      // create a bunch of dummy test files to reproduce #1305
+      await fs.mkdirp(integrationPath)
+      await Promise.all(
+        _.times(15, (i) => fs.writeFile(path.join(integrationPath, `${i}.spec.js`), `it('test', () => {})`)),
+      )
+
+      const { stderr } = await exec()
+
+      expect(stderr).to.not.include('setMaxListeners')
+      expect(stderr).to.not.include('preprocessor:close')
+    },
+  })
+})

packages/server/test/integration/cypress_spec.js

@@ -1143,6 +1143,7 @@ describe('lib/cypress', () => {
             setProxy: sinon.stub().resolves(),
             setUserAgent: sinon.stub(),
             on: sinon.stub(),
+            removeListener: sinon.stub(),
           },
         }
 

packages/server/test/support/fixtures/projects/max-listeners/cypress.json

@@ -0,0 +1 @@
+{}

packages/server/test/support/helpers/e2e.ts

@@ -416,7 +416,6 @@ const e2e = {
 
       if (process.env.NO_EXIT) {
         Fixtures.scaffoldWatch()
-        process.env.CYPRESS_INTERNAL_E2E_TESTS
       }
 
       sinon.stub(process, 'exit')

packages/server/test/unit/suppress_warnings_spec.ts

@@ -6,9 +6,9 @@ import proxyquire from 'proxyquire'
 const ERROR_MESSAGE = 'Setting the NODE_TLS_REJECT_UNAUTHORIZED'
 
 const TLS_CONNECT = `require('tls').connect().on('error', ()=>{});`
-const SUPPRESS_WARNING = `require('${__dirname}/../../lib/util/suppress_unauthorized_warning').suppress();`
+const SUPPRESS_WARNING = `require('${__dirname}/../../lib/util/suppress_warnings').suppress();`
 
-describe('lib/util/suppress_unauthorized_warning', function () {
+describe('lib/util/suppress_warnings', function () {
   it('tls.connect emits warning if NODE_TLS_REJECT_UNAUTHORIZED=0 and not suppressed', function () {
     return execa.shell(`node -e "${TLS_CONNECT}"`, {
       env: {
@@ -36,7 +36,7 @@ describe('lib/util/suppress_unauthorized_warning', function () {
     const emitWarning = sinon.spy(process, 'emitWarning')
 
     // force typescript to always be non-requireable
-    const { suppress } = proxyquire('../../lib/util/suppress_unauthorized_warning', {})
+    const { suppress } = proxyquire('../../lib/util/suppress_warnings', {})
 
     suppress()