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next.js/test/unit/EventEmitter.test.js
Tim Neutkens 15bb1c5e79
Use Typescript to transpile Next.js core files instead of Babel (#5747)
- Replaces taskr-babel with taskr-typescript for the `next` package
- Makes sure Node 8+ is used, no unneeded transpilation
- Compile Next.js client side files through babel the same way pages are
- Compile Next.js client side files to esmodules, not commonjs, so that tree shaking works.
- Move error-debug.js out of next-server as it's only used/require in development
- Drop ansi-html as dependency from next-server
- Make next/link esmodule (for tree-shaking)
- Make next/router esmodule (for tree-shaking)
- add typescript compilation to next-server
- Remove last remains of Flow
- Move hoist-non-react-statics to next, out of next-server
- Move htmlescape to next, out of next-server
- Remove runtime-corejs2 from next-server
2018-11-28 15:03:02 +01:00

107 lines
2.5 KiB
JavaScript

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