stubbing module exports with closures

[markbrown4]

I can't seem to find a way to gracefully stub the exported a() here:

// lib.js
const a = () => {}
const b = () => {
  a()
}

module.exports = { a, b }

// test.js
const assert = require('assert')
const sinon = require('sinon')

const lib = require('./lib')
const stub = sinon.stub(lib, 'a')
lib.b()
assert(stub.called)

I'm guessing this fails because b has it's own copy of a.
I can do something like this which makes the test pass but it makes me want to take a shower.

const a = () => {}
const b = () => {
  toExport.a()
}

const toExport = { a, b }

module.exports = toExport

Any other options?

Cheers,

[fatso83]

You need to have a way of injecting your stub to do this cleanly. Something like

...
module.exports = { 
    a, 
    b, 
    __injectA = function(fn){ a = fn; },
    __injectB = function(fn){ b = fn; } 
}

Of course, since you are changing the internals of the module it will affect everything else using this module. If you want to do this without altering some kind of global state, you will need to create those functions in a closure created by some exported init function.

[markbrown4]

Ah, that makes sense. Thank you!

…

On Thu, 26 Jan 2017 at 2:33 pm, Carl-Erik Kopseng ***@***.***> wrote: You need to have a way of injecting your stub to do this cleanly. Something like ... module.exports = { a, b, __injectA = function(fn){ a = fn; }, __injectB = function(fn){ b = fn; } } Of course, since you are changing the internals of the module it will affect everything else using this module. If you want to do this without altering some kind of global state, you will need to create those functions in a closure created by some exported init function. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#1248 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAImTsNjkfSDrIRFQsv9Fe9JJZaX538Gks5rWK51gaJpZM4LtsJg> .