Add support for npm3 or dedupe

[Frizi]

Right now phantomjs bin path is hardcoded here
https://github.com/localnerve/html-snapshots/blob/master/lib/html-snapshots.js#L23

When html-snapshots is installed with npm3 (or dedupe was used), phantom is installed in different location. In my case this path would work '../../.bin/phantomjs', but you cannot assume that really.

You may try your luck with this code from karma-phantomjs-launcher:

var phantomJSExePath = function () {
  // If the path we're given by phantomjs is to a .cmd, it is pointing to a global copy. 
  // Using the cmd as the process to execute causes problems cleaning up the processes 
  // so we walk from the cmd to the phantomjs.exe and use that instead.

  var phantomSource = require('phantomjs').path;

  if (path.extname(phantomSource).toLowerCase() === '.cmd') {
    return path.join(path.dirname( phantomSource ), '//node_modules//phantomjs//lib//phantom//phantomjs.exe');
  }

  return phantomSource;
};

[localnerve]

This has always been an issue - well before npm3.
The hard-coded path you reference is just a default.

The default bin path can be overriden with the phantomjs option, found at the bottom of this section in the readme.
So, the phantomjs supplied with this lib is entirely optional.

I'm assuming you are suggesting that there should be a different default phantomjs location. I've a couple of questions on that implied suggestion:

1. What phantomjs location & version are you actively referencing that prompted this issue (presume via this lib pkg json)?
   I ask this because last year we found a package driven MacOSX difference that invalidated referencing phantomjs/lib/phantom/phantomjs.exe directly (perms on file not executable after install). Maybe this has changed again and would be good to know which version to get to test a next change.
   Also, could be that you are getting a different phantomjs in your particular project dep situation.
2. Is npm3 changing files/folders?
3. Is the package referenced in karma-phantomjs-launcher using the same phantomjs package referenced by this lib?

Thanks in advance for any additional feedback you can supply.

[Frizi]

1. paths to all 3 modules:
   • node_modules/html-snapshots, v0.8.1, dependency on phantomjs ^1.9.16
   • node_modules/karma-phantomjs-launcher, v0.1.4, dependency on phantomjs ~1.9
   • node_modules/phantomjs, v1.9.17
2. packages are now installed as flat as possible, per-package node_modules folder is only created when there is a version conflict.
   https://github.com/npm/npm/releases/tag/v3.0.0 check section "Flat, flat, flat!"
3. Yes, at least this lib should use it, but doesn't properly.

Simple require('phantomjs') will always refer to the correct path, so it should be a preferred solution to find a module.

[localnerve]

Let's be more specific on what you are saying the change should be (So I'm certain I understand). Here's my attempt:

Update the default phantomjs path value used by this package to be dependent on the path property exported from the phantomjs npm package. The default value will now come from this code in the phantomjs package.

Using this property should always be the correct path for all npm versions, and will serve well in the npm3, dedupe case.

Easy enough, please confirm I got it right.
Thanks!

[Frizi]

Yes, you got it right. The code I posted at the top is actually working well in all these cases. Just remember to allow the user to alter this path anyway.

[localnerve]

OK, I have a release candidate that runs correctly on Linux. It also makes successful substitutions via the phantomjs option (this is how I run on Travis-CI).

I noticed that this technique (you posted from above, the essence of the change) is only used by karma-phantomjs-launcher for win32.
I'm using it for every/any platform. Works for Linux.

Can you please review (c2f5e28) the change and test your use case? Also, let me know your OS. I'll be spinning up a Mac test shortly.

One way to test: Drop the RC in your package.json via git://github.com/localnerve/html-snapshots#rc-0.10.0
(do npm update, not install after that tweak)

[localnerve]

I've confirmed working on mac, any feedback in your use case?