perf: ensure the pausing event listeners are removed

cli/CHANGELOG.md

@@ -3,6 +3,10 @@
 
 _Released 5/6/2025 (PENDING)_
 
+**Performance:**
+
+- Ensure the previous pausing event handlers are removed before new ones are added. Addressed in [#31596](https://github.com/cypress-io/cypress/pull/31596).
+
 **Bugfixes:**
 
 - Fixed an issue where the configuration setting `trashAssetsBeforeRuns=false` was ignored for assets in the `videosFolder`. These assets were incorrectly deleted before running tests with `cypress run`. Addresses [#8280](https://github.com/cypress-io/cypress/issues/8280).

packages/app/cypress/e2e/runner/event-manager.cy.ts

@@ -1,11 +1,11 @@
-import { loadSpec } from './support/spec-loader'
+import { loadSpec, shouldHaveTestResults } from './support/spec-loader'
 
 describe('event-manager', () => {
   it('emits the cypress:created event when spec is rerun', () => {
     // load the spec initially
     loadSpec({
       filePath: 'hooks/basic.cy.js',
-      passCount: 1,
+      passCount: 2,
     })
 
     cy.window().then((win) => {
@@ -26,4 +26,28 @@ describe('event-manager', () => {
       cy.wrap(() => eventReceived).invoke('call').should('be.true')
     })
   })
+
+  it('clears the pause listeners when the spec is rerun', () => {
+    loadSpec({
+      filePath: 'hooks/basic.cy.js',
+      passCount: 2,
+    })
+
+    cy.window().then((win) => {
+      const eventManager = win.getEventManager()
+
+      cy.wrap(() => eventManager.reporterBus.listeners('runner:next').length).invoke('call').should('equal', 1)
+
+      // trigger a rerun
+      cy.get('.restart').click()
+
+      shouldHaveTestResults({
+        passCount: 2,
+        failCount: 0,
+        pendingCount: 0,
+      })
+
+      cy.wrap(() => eventManager.reporterBus.listeners('runner:next').length).invoke('call').should('equal', 1)
+    })
+  })
 })

packages/app/src/runner/events/capture-protocol.ts

@@ -75,7 +75,6 @@ export const addCaptureProtocolListeners = (Cypress: Cypress.Cypress) => {
   }
 
   Cypress.on('viewport:changed', viewportChangedHandler)
-  // @ts-expect-error
   Cypress.primaryOriginCommunicator.on('viewport:changed', viewportChangedHandler)
 
   Cypress.on('test:before:run:async', async (attributes) => {

packages/app/src/runner/events/pausing.ts

@@ -1,12 +1,18 @@
-export const handlePausing = (getCypress, reporterBus) => {
-  const Cypress = getCypress()
-  // tracks whether the cy.pause() was called from the primary driver
-  // (value === null) or from a cross-origin spec bridge (value is the origin
-  // matching that spec bridge)
-  let sendEventsToOrigin = null
+// tracks whether the cy.pause() was called from the primary driver
+// (value === null) or from a cross-origin spec bridge (value is the origin
 
-  reporterBus.on('runner:next', () => {
-    const Cypress = getCypress()
+import type EventEmitter from 'events'
+
+// matching that spec bridge)
+let sendEventsToOrigin: string | null = null
+
+type GetCypressFunction = () => Cypress.Cypress
+
+class PauseHandlers {
+  constructor (private getCypress: GetCypressFunction, private reporterBus: EventEmitter) {}
+
+  nextHandler = () => {
+    const Cypress = this.getCypress()
 
     if (!Cypress) return
 
@@ -17,10 +23,10 @@ export const handlePausing = (getCypress, reporterBus) => {
     } else {
       Cypress.emit('resume:next')
     }
-  })
+  }
 
-  reporterBus.on('runner:resume', () => {
-    const Cypress = getCypress()
+  resumeHandler = () => {
+    const Cypress = this.getCypress()
 
     if (!Cypress) return
 
@@ -34,17 +40,45 @@ export const handlePausing = (getCypress, reporterBus) => {
 
     // pause sequence is over - reset this for subsequent pauses
     sendEventsToOrigin = null
-  })
+  }
 
-  // from the primary driver
-  Cypress.on('paused', (nextCommandName) => {
-    reporterBus.emit('paused', nextCommandName)
-  })
+  pausedHandler = (nextCommandName: string) => {
+    this.reporterBus.emit('paused', nextCommandName)
+  }
 
-  // from a cross-origin spec bridge
-  Cypress.primaryOriginCommunicator.on('paused', ({ nextCommandName, origin }) => {
+  crossOriginPausedHandler = ({ nextCommandName, origin }: { nextCommandName: string, origin: string }) => {
     sendEventsToOrigin = origin
+    this.reporterBus.emit('paused', nextCommandName)
+  }
+
+  removeListeners = () => {
+    const Cypress = this.getCypress()
+
+    this.reporterBus.removeListener('runner:next', this.nextHandler)
+    this.reporterBus.removeListener('runner:resume', this.resumeHandler)
+    Cypress.removeListener('paused', this.pausedHandler)
+    Cypress.primaryOriginCommunicator.removeListener('paused', this.crossOriginPausedHandler)
+  }
+
+  addListeners = () => {
+    const Cypress = this.getCypress()
+
+    this.reporterBus.on('runner:next', this.nextHandler)
+    this.reporterBus.on('runner:resume', this.resumeHandler)
+    Cypress.on('paused', this.pausedHandler)
+    Cypress.primaryOriginCommunicator.on('paused', this.crossOriginPausedHandler)
+  }
+}
+
+let currentHandlers: PauseHandlers | null = null
+
+export const handlePausing = (getCypress: GetCypressFunction, reporterBus: EventEmitter) => {
+  // Remove existing handlers if they exist
+  if (currentHandlers) {
+    currentHandlers.removeListeners()
+  }
 
-    reporterBus.emit('paused', nextCommandName)
-  })
+  // Create new handlers
+  currentHandlers = new PauseHandlers(getCypress, reporterBus)
+  currentHandlers.addListeners()
 }

packages/driver/types/internal-types-lite.d.ts

@@ -7,6 +7,12 @@ declare namespace Cypress {
   interface Cypress {
     runner: any
     state: State
+    emit: import('eventemitter2').EventEmitter2['emit']
+    removeListener: import('eventemitter2').EventEmitter2['removeListener']
+    primaryOriginCommunicator: import('eventemitter2').EventEmitter2 & {
+      toSpecBridge: (origin: string, event: string, data?: any, responseEvent?: string) => void
+      userInvocationStack?: string
+    }
   }
 
   interface Actions {
@@ -23,6 +29,7 @@ declare namespace Cypress {
     (action: 'test:after:run:async', fn: (attributes: ObjectLike, test: Mocha.Test) => void)
     (action: 'cy:protocol-snapshot', fn: () => void)
     (action: 'test:before:after:run:async', fn: (attributes: ObjectLike, test: Mocha.Test, options: ObjectLike) => void | Promise<any>): Cypress
+    (action: 'paused', fn: (nextCommandName: string) => void)
   }
 
   interface Backend {

packages/driver/types/internal-types.d.ts

@@ -51,10 +51,7 @@ declare namespace Cypress {
     }
     sinon: sinon.SinonApi
     utils: CypressUtils
-    state: State
     events: Events
-    emit: (event: string, payload?: any) => void
-    primaryOriginCommunicator: import('../src/cross-origin/communicator').PrimaryOriginCommunicator
     specBridgeCommunicator: import('../src/cross-origin/communicator').SpecBridgeCommunicator
     mocha: $Mocha
     configure: (config: Cypress.ObjectLike) => void
@@ -96,7 +93,7 @@ declare namespace Cypress {
     (action: 'before:stability:release', fn: () => void)
     (action: '_log:added', fn: (attributes: ObjectLike, log: Cypress.Log) => void): Cypress
     (action: '_log:changed', fn: (attributes: ObjectLike, log: Cypress.Log) => void): Cypress
-    (action: 'paused', fn: (nextCommandName: string) => void)
+    (action: 'resume:all', fn: () => void)
   }
 
   interface Backend {