Dark-hole NPM | npm.io

dark-hole

dark-hole swallows(accepts) everything, and everything just disappears(gone). Like a blackhole.

dark-hole is useful if you pretend to implement some interfaces but not actually implement them.

And you could trace everything that swallowed by dark-hole, which is very useful for testing purpose.

Install

$ npm i dark-hole

Usage

const {
  create,
  trace
} = require('dark-hole')

// Create a blackhole which swallows everything
const blackhole = create()

const returnValue = blackhole
.whateverProperty          // 1
.asAccessingArrayItem[0]   // 2, 3
.runFunction('blah blah')  // 3, 4
.destroyTheWorld           // 5
.boooooooom                // 6
.neverDie()                // 7, 8
// Nothing happens. Nothing. Without errors.

Trace accessing and invoking

// Create a tracer which could trace back upon time
// to the very beginning of the `blackhole`
// just like a time machine
const tracer = trace(returnValue)

// `willBeCalledWith()` returns a new tracker afterwards
// if there is a match
const after4 = tracer.willBeCalledWith({
  // accessing the property from any time spot is ok
  accessor: 'asAccessingArrayItem.0.runFunction',
  args: ['blah blah']
})

try {
  tracer.willBeCalledWith({
    accessor: 'asAccessingArrayItem.0.runFunction',
    args: ['blah blah'],
    // The accessing must happens immediately
    immediately: true
  })
} catch (err) {
  console.log(err.code)
  // 'NO_MATCH'
  // It was not accessed immediately.
}

Only trace accessing

const after7 = after4.willBeAccessedBy({
  // `accessor` could be an array
  accessor: ['destroyTheWorld', 'boooooooom', 'neverDie'],
  immediately: true
})

// No errors

Only trace function call

const end = after7.willBeCalledWith({
  args: [],
  immediately: true
})

console.log(end.ended)
// true
// , if nothing happens afterwards

APIs

create() : Proxy

Returns a dark hole

trace(DarkHole) : Tracer

tracer.willBeCalledWith(options): Tracer

accessor? string | Array<string>
thisArg? any If options does not contain the 'thisArg' property, then it will match any this argument. Or it will do a exact match.
args? Array<any>=[]
immediately? boolean

Returns Tracer if there is a match.

Or an NO_MATCH error will be thrown.