mirror of
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107 lines
2.5 KiB
JavaScript
107 lines
2.5 KiB
JavaScript
/* eslint-env jest */
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import EventEmitter from 'next-server/dist/lib/EventEmitter'
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describe('EventEmitter', () => {
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describe('With listeners', () => {
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it('should listen to a event', (done) => {
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const ev = new EventEmitter()
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ev.on('sample', done)
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ev.emit('sample')
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})
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it('should listen to multiple listeners', () => {
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const ev = new EventEmitter()
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let cnt = 0
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ev.on('sample', () => { cnt += 1 })
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ev.on('sample', () => { cnt += 1 })
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ev.emit('sample')
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expect(cnt).toBe(2)
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})
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it('should listen to multiple events', () => {
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const ev = new EventEmitter()
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const data = []
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const cb = (name) => { data.push(name) }
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ev.on('sample1', cb)
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ev.on('sample2', cb)
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ev.emit('sample1', 'one')
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ev.emit('sample2', 'two')
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expect(data).toEqual(['one', 'two'])
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})
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it('should support multiple arguments', () => {
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const ev = new EventEmitter()
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let data
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ev.on('sample', (...args) => { data = args })
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ev.emit('sample', 'one', 'two')
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expect(data).toEqual(['one', 'two'])
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})
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it('should possible to stop listening an event', () => {
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const ev = new EventEmitter()
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let cnt = 0
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const cb = () => { cnt += 1 }
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ev.on('sample', cb)
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ev.emit('sample')
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expect(cnt).toBe(1)
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ev.off('sample', cb)
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ev.emit('sample')
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expect(cnt).toBe(1)
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})
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it('should throw when try to add the same listener multiple times', () => {
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const ev = new EventEmitter()
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const cb = () => {}
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ev.on('sample', cb)
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const run = () => ev.on('sample', cb)
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expect(run).toThrow(/Listener already exists for router event: `sample`/)
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})
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it('should support chaining like the nodejs EventEmitter', () => {
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const emitter = new EventEmitter()
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let calledA = false
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let calledB = false
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emitter
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.on('a', () => { calledA = true })
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.on('b', () => { calledB = true })
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emitter.emit('a')
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emitter.emit('b')
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expect(calledA).toEqual(true)
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expect(calledB).toEqual(true)
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})
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it('should return an indication on emit if there were listeners', () => {
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const emitter = new EventEmitter()
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emitter.on('a', () => { })
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expect(emitter.emit('a')).toEqual(true)
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expect(emitter.emit('b')).toEqual(false)
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})
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})
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describe('Without a listener', () => {
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it('should not fail to emit', () => {
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const ev = new EventEmitter()
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ev.emit('aaaa', 10, 20)
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})
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})
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})
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