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).
+
 **Misc:**
 
 - The URL in the Cypress App no longer displays a white background when the URL is loading. Fixes [#31556](https://github.com/cypress-io/cypress/issues/31556).

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/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 EventEmitter from 'events'
+
+// matching that spec bridge)
+let sendEventsToOrigin: string | null = null
+
+type GetCypressFunction = () => any
+
+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()
 }