Fix for Issue #39 regarding NODE_PATH

[job13er]

• Added tests to test/node_path.js to ensure $NODE_PATH environment
  variable is respected when searching for a module.
• Updated the node-modules-paths module to include the directories
  specified by process.env.NODE_PATH.

[job13er]

Fixes #39

[job13er]

Let me know if you'd rather not include this in the PR. I'm not sure how you handle your releases.

[job13er]

Anyone know how to simulate the environment in the travis build system? I can't reproduce the build failure. I installed nvm and used the same commands as the travis build and got clean results

[job13er]

Nevermind, I figured it out, they have / in the NODE_PATH and so some other code is breaking once NODE_PATH is checked. I'll fix it.

[ghost]

This is what opts.path is for. An implicit $NODE_PATH argument here seems very surprising.

[pikajude]

So if people are using NODE_PATH, and a project they want to install uses resolve.sync() instead of require(), they'll get an error? Is that intended behavior? Isn't this what NODE_PATH is for?

[job13er]

@joelteon

So if people are using NODE_PATH, and a project they want to install uses resolve.sync() instead of require(), they'll get an error?

Yes. We ran into that, which is why I tried to submit this fix. We weren't using node-resolve ourselves, but something we were consuming was, and since node-resolve didn't look in NODE_PATH we got an error.

Is that intended behavior?

Apparently, since my PR was dismissed. I guess it's intended or anyone who wants to use NODE_PATH to either

1. Not use any projects which use node-resolve
2. Use patched versions of every project that uses node-resolve to update their opts.path setting to account for NODE_PATH (as suggested above)
3. Stop using NODE_PATH

We ended up going with option 3, since it appeared support for NODE_PATH wasn't very complete across libraries such as this one. And unlikely to change in the near future based on the response I got when I tried to add support for it here.

Isn't this what NODE_PATH is for?

We thought so. However, the latest docs do suggest not using NODE_PATH "You are highly encouraged to place your dependencies locally in node_modules folders. They will be loaded faster, and more reliably."