Doesn't fail if a dependency is not loaded

[bengourley]

Example below. I would expect an error to be passed as the first argument where I am doing a console.log(). Not only does it not get an error, but it looks like the callback is not called at all and this program just terminates.

var loader = require('component-loader')

loader([ component ], function (cb) { return cb }, function () {
  console.log(arguments)
})

function component() {
  return { component: [ 'nonExistentCompent', init ] }
  function init(cb) { cb() }
}

[bengourley]

This is actually really posing a problem. If you specify a dependency and it doesn't exist, your callback is never called and you don't know what one is missing. If you have lots of components it makes it really hard to track down.

[microadam]

Hmm, it just uses async.auto under the hood, so its quite possible that its a problem with that

[bengourley]

The async maintainer closed a feature request for it: caolan/async#263

This is a pretty fundamental issue with component-loader and definitely needs fixing. If we are going to go the dependency-resolution route it needs to work properly.

[microadam]

Thought I may have been stung by this problem, so I wrote the following to test:

  var _ = require('lodash')
    , componentNames = []
    , dependencies = []

  components.forEach(function (component) {
    var c = component()
      , name = Object.keys(c)[0]
      , deps = c[name]

    componentNames.push(name)
    if (Array.isArray(deps)) {
      deps.pop()
      dependencies = dependencies.concat(deps)
    }
  })

  dependencies = _.uniq(dependencies)
  var missingDependencies = _.difference(dependencies, componentNames)
  console.log(missingDependencies)

Just putting here so it doesn't get lost. Will integrate into the module and release a new version when I can

[domharrington]

Circular dependencies also cause a problem. This may be a bug with the code but it becomes very hard to track this down when async.auto never calls the callback.

var loader = require('component-loader')

loader([ a, b ], function (cb) { return cb }, function () {
  console.log(arguments)
})

function a() {
  return { a: [ 'b', init ] }
  function init(cb) { cb() }
}

function b() {
  return { b: [ 'a', init ] }
  function init(cb) { cb() }
}

[serby]

Olly just fell foul of this issue too. There must be something can can be done in component-loader to make this throw a decent error if there is a cyclic dependancy graph or a missing dependancy.

[microadam]

Both situations now throw an error in v0.1.0