events-to-array

events-to-array

Put a bunch of emitted events in an array, for testing.

If any of the emitted arguments are event emitters, then they'll also be tracked, and replaced in the array with their tracking array. (This is less confusing in practice than it sounds in text, see below.) The only caveat is that the events in the child event emitter and in the parent are not preserved in order, so this lib doesn't tell you whether the child events happened before or after any subsequent parent events.

USAGE

var assert = require('assert')
var EE = require('events')
var etoa = require('events-to-array')
var emitter = new EE()
var array = etoa(emitter)

emitter.emit('foo', 1, 2, 3)
emitter.emit('bar', { x: 1 })

// nested events get tracked as well
var subemit = new EE()
emitter.emit('sub', subemit)
subemit.emit('childEvent', { some: 'data' })
subemit.emit('anotherone', { some: 'data' }, 'many', 'args')

// CAVEAT!  See above in the wordy part of this readme.
// Note that the blaz/blorrg event comes after the child, and there's
// no way to know that the child 'order not preserved' event happened
// after.
emitter.emit('blaz', 'blorrg')
subemit.emit('order', 'not', 'preserved between child and parent')

// check out the array whenever
assert.deepEqual(array,
[ [ 'foo', 1, 2, 3 ],
  [ 'bar', { x: 1 } ],
  [ 'sub',
    [ [ 'childEvent', { some: 'data' } ],
      [ 'anotherone', { some: 'data' }, 'many', 'args' ],
      [ 'order', 'not', 'preserved between child and parent' ] ] ],
  [ 'blaz', 'blorrg' ] ])

eventsToArray(emitter, [ignoreList], [mapFunction])

Returns an array with all the events emitted by the emitter.

It's your responsibility to know when to check it for the events that you expected to have received.

The ignoreList is an array of event names to ignore.

The mapFunction is a function that takes a list of arguments and returns a potentially-mutated array of arguments. Note that child event emitters will already have been swapped out for an events-to-array list so that nested events are caught.

This is handy, for example, for swapping out large Buffer objects with something like {type: 'buffer', length: 123456} rather than blow up the JSON fixtures.

The map function is called on the args list as map(arg, index, list)