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Diffstat (limited to 'remote/test/puppeteer/test/src/EventEmitter.spec.ts')
-rw-r--r-- | remote/test/puppeteer/test/src/EventEmitter.spec.ts | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/remote/test/puppeteer/test/src/EventEmitter.spec.ts b/remote/test/puppeteer/test/src/EventEmitter.spec.ts new file mode 100644 index 0000000000..ef5a6cc065 --- /dev/null +++ b/remote/test/puppeteer/test/src/EventEmitter.spec.ts @@ -0,0 +1,170 @@ +/** + * Copyright 2020 Google Inc. All rights reserved. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +import expect from 'expect'; +import {EventEmitter} from 'puppeteer-core/internal/common/EventEmitter.js'; +import sinon from 'sinon'; + +describe('EventEmitter', () => { + let emitter: EventEmitter; + + beforeEach(() => { + emitter = new EventEmitter(); + }); + + describe('on', () => { + const onTests = (methodName: 'on' | 'addListener'): void => { + it(`${methodName}: adds an event listener that is fired when the event is emitted`, () => { + const listener = sinon.spy(); + emitter[methodName]('foo', listener); + emitter.emit('foo'); + expect(listener.callCount).toEqual(1); + }); + + it(`${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'); + expect(listener.callCount).toEqual(1); + emitter.off('foo', listener); + emitter.emit('foo'); + 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'); + expect(listener.callCount).toEqual(1); + emitter.emit('foo'); + 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'); + + 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')).toBe(true); + }); + + it('returns false if the event has listeners', () => { + const listener = sinon.spy(); + emitter.on('foo', listener); + expect(emitter.emit('notFoo')).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')).toBe(false); + expect(emitter.emit('bar')).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')).toBe(true); + expect(emitter.emit('bar')).toBe(false); + }); + }); +}); |