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Diffstat (limited to 'remote/test/puppeteer/packages/puppeteer-core/src/common/EventEmitter.test.ts')
-rw-r--r-- | remote/test/puppeteer/packages/puppeteer-core/src/common/EventEmitter.test.ts | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/remote/test/puppeteer/packages/puppeteer-core/src/common/EventEmitter.test.ts b/remote/test/puppeteer/packages/puppeteer-core/src/common/EventEmitter.test.ts new file mode 100644 index 0000000000..cf05ef6700 --- /dev/null +++ b/remote/test/puppeteer/packages/puppeteer-core/src/common/EventEmitter.test.ts @@ -0,0 +1,185 @@ +/** + * @license + * Copyright 2023 Google Inc. + * SPDX-License-Identifier: Apache-2.0 + */ + +import {describe, it, beforeEach} from 'node:test'; + +import expect from 'expect'; +import sinon from 'sinon'; + +import {EventEmitter} from './EventEmitter.js'; + +describe('EventEmitter', () => { + let emitter: EventEmitter<Record<string, unknown>>; + + beforeEach(() => { + emitter = new EventEmitter(); + }); + + describe('on', () => { + const onTests = (methodName: 'on' | 'addListener'): void => { + it(`${methodName}: adds an event listener that is fired when the event is emitted`, () => { + const listener = sinon.spy(); + emitter[methodName]('foo', listener); + emitter.emit('foo', undefined); + expect(listener.callCount).toEqual(1); + }); + + it(`${methodName} sends the event data to the handler`, () => { + const listener = sinon.spy(); + const data = {}; + emitter[methodName]('foo', listener); + emitter.emit('foo', data); + expect(listener.callCount).toEqual(1); + expect(listener.firstCall.args[0]).toBe(data); + }); + + it(`${methodName}: supports chaining`, () => { + const listener = sinon.spy(); + const returnValue = emitter[methodName]('foo', listener); + expect(returnValue).toBe(emitter); + }); + }; + onTests('on'); + // we support addListener for legacy reasons + onTests('addListener'); + }); + + describe('off', () => { + const offTests = (methodName: 'off' | 'removeListener'): void => { + it(`${methodName}: removes the listener so it is no longer called`, () => { + const listener = sinon.spy(); + emitter.on('foo', listener); + emitter.emit('foo', undefined); + expect(listener.callCount).toEqual(1); + emitter.off('foo', listener); + emitter.emit('foo', undefined); + expect(listener.callCount).toEqual(1); + }); + + it(`${methodName}: supports chaining`, () => { + const listener = sinon.spy(); + emitter.on('foo', listener); + const returnValue = emitter.off('foo', listener); + expect(returnValue).toBe(emitter); + }); + }; + offTests('off'); + // we support removeListener for legacy reasons + offTests('removeListener'); + }); + + describe('once', () => { + it('only calls the listener once and then removes it', () => { + const listener = sinon.spy(); + emitter.once('foo', listener); + emitter.emit('foo', undefined); + expect(listener.callCount).toEqual(1); + emitter.emit('foo', undefined); + expect(listener.callCount).toEqual(1); + }); + + it('supports chaining', () => { + const listener = sinon.spy(); + const returnValue = emitter.once('foo', listener); + expect(returnValue).toBe(emitter); + }); + }); + + describe('emit', () => { + it('calls all the listeners for an event', () => { + const listener1 = sinon.spy(); + const listener2 = sinon.spy(); + const listener3 = sinon.spy(); + emitter.on('foo', listener1).on('foo', listener2).on('bar', listener3); + + emitter.emit('foo', undefined); + + expect(listener1.callCount).toEqual(1); + expect(listener2.callCount).toEqual(1); + expect(listener3.callCount).toEqual(0); + }); + + it('passes data through to the listener', () => { + const listener = sinon.spy(); + emitter.on('foo', listener); + const data = {}; + + emitter.emit('foo', data); + expect(listener.callCount).toEqual(1); + expect(listener.firstCall.args[0]).toBe(data); + }); + + it('returns true if the event has listeners', () => { + const listener = sinon.spy(); + emitter.on('foo', listener); + expect(emitter.emit('foo', undefined)).toBe(true); + }); + + it('returns false if the event has listeners', () => { + const listener = sinon.spy(); + emitter.on('foo', listener); + expect(emitter.emit('notFoo', undefined)).toBe(false); + }); + }); + + describe('listenerCount', () => { + it('returns the number of listeners for the given event', () => { + emitter.on('foo', () => {}); + emitter.on('foo', () => {}); + emitter.on('bar', () => {}); + expect(emitter.listenerCount('foo')).toEqual(2); + expect(emitter.listenerCount('bar')).toEqual(1); + expect(emitter.listenerCount('noListeners')).toEqual(0); + }); + }); + + describe('removeAllListeners', () => { + it('removes every listener from all events by default', () => { + emitter.on('foo', () => {}).on('bar', () => {}); + + emitter.removeAllListeners(); + expect(emitter.emit('foo', undefined)).toBe(false); + expect(emitter.emit('bar', undefined)).toBe(false); + }); + + it('returns the emitter for chaining', () => { + expect(emitter.removeAllListeners()).toBe(emitter); + }); + + it('can filter to remove only listeners for a given event name', () => { + emitter + .on('foo', () => {}) + .on('bar', () => {}) + .on('bar', () => {}); + + emitter.removeAllListeners('bar'); + expect(emitter.emit('foo', undefined)).toBe(true); + expect(emitter.emit('bar', undefined)).toBe(false); + }); + }); + + describe('dispose', () => { + it('should dispose higher order emitters properly', () => { + let values = ''; + emitter.on('foo', () => { + values += '1'; + }); + const higherOrderEmitter = new EventEmitter(emitter); + + higherOrderEmitter.on('foo', () => { + values += '2'; + }); + higherOrderEmitter.emit('foo', undefined); + + expect(values).toMatch('12'); + + higherOrderEmitter.off('foo'); + higherOrderEmitter.emit('foo', undefined); + + expect(values).toMatch('121'); + }); + }); +}); |