feat(local-install): Add npmEnv option to LocalInstaller

[wojtkowiak]

Hello,

I have a plan to use your package in meteor-desktop but I've faced a problem when installing local packages that have native node modules. The compilation goes against current node and what I need is to compile them against the electron version. For that I need to pass additional env vars to npm. I have made this small change to be able to do that.
I am a total newbie in typescript so I hope its typescriptish enough 🙂
Let me know if that can go into your next release.

[nicojs]

Thanks for your PR! Looks good so far. I have a few remarks.

I'm also missing a small update in the readme and some tests. Do you need some help with that?

Are you planning to use it from the programmatic API and not the CLI?

[nicojs]

Could we use Object.assign here? options = Object.assign({}, options);

[wojtkowiak]

sure, good point

[nicojs]

Object.assign can handle an undefined value. So you can even remove this entire if:

 constructor(sourcesByTarget: ListByPackage, options?: Options) {
         super();
         this.sourcesByTarget = resolve(sourcesByTarget);
         this.options = Object.assign({}, options);
     }

[nicojs]

the ExecOptions are actually re-exported from mz/child_process (using export * from "child_process";), so you should be able to use import { exec, ExecOptions } from 'mz/child_process'; instead.

[wojtkowiak]

Oww, good to know, much more cleaner that way.

[nicojs]

You've got to love mutation testing. Build failed because new code paths do not have unit tests:

Final mutation score 71.43 under breaking threshold 72, setting exit code to 1 (failure).

[wojtkowiak]

Thanks for looking into this 🙂
Sorry for the delay, I needed to handle some other issues.
I have adjusted the commit according to your comments and added the test. I have also added a section in the Readme. Feel free to modify it.

Are you planning to use it from the programmatic API and not the CLI?

I guess it would be difficult to use it from the CLI. I mean passing an object from CLI would be hard. Maybe there should be an option to pass it when using the CLI interface programmatically but not sure if it's worth it.

[wojtkowiak]

Would you have a moment to take a look?

[nicojs]

Sorry it took so long. I somehow missed the update from git. Thanks for the reminder

[nicojs]

Object.assign can handle an undefined value. So you can even remove this entire if:

 constructor(sourcesByTarget: ListByPackage, options?: Options) {
         super();
         this.sourcesByTarget = resolve(sourcesByTarget);
         this.options = Object.assign({}, options);
     }

[nicojs]

It's released in v0.5.0: https://github.com/nicojs/node-install-local/blob/master/CHANGELOG.md

[wojtkowiak]

Thanks for your time and for merging it in! 👍