Add support for the build_from_source npm config

[adipascu]

Implements #98

[vweevers]

Can you add tests to rc-test.js?

[adipascu]

I have updated the tests.

Seems like this line is no longer required for my build, removing this line also passes the existing tests.
Npm sets flags into process.env using this piece of code. Any flag like --some-str gets set into process.env as npm_config_some_str. This might also apply to the target, runtime and arch flags.

Might be a breaking change for some peaople, leaving it as is for now.

Edit: I am ending my day, feel free to edit or add new commits. 👋

[vweevers]

Seems like this line is no longer required for my build, removing this line also passes the existing tests.

Yeah, I'm also a little fuzzy on the precedence here, I wanna take a closer look myself.

[vweevers]

How should it work when you have build_from_source=true in npmrc, but install with npm i --build-from-source=non-matching-package-name? That should result in false, right?

[adipascu]

The settings from .npmrc have priority over flags passed in the CLI.
If you pass both, npm will set the env value to whatever is inside .npmrc, if this is a package name, it will only rebuild that package. If its true it will rebuild all packages.

[vweevers]

The settings from .npmrc have priority over flags passed in the CLI.

Generally they don't. And for build-from-source that isn't true either; in node-pre-gyp the dashed command line option takes precedence over the underscored rc/env option:

var source_build = gyp.opts['build-from-source'] || gyp.opts.build_from_source

So to stay in line with node-pre-gyp, we should also modify this to support --build-from-source=x:

prebuild-install/rc.js

Lines 12 to 26 in ba21172

	var npmargs = ['prebuild', 'compile', 'build-from-source', 'debug']
	try {
	var npmArgv = JSON.parse(env.npm_config_argv).cooked
	for (var i = 0; i < npmargs.length; ++i) {
	if (npmArgv.indexOf('--' + npmargs[i]) !== -1) {
	process.argv.push('--' + npmargs[i])
	}
	if (npmArgv.indexOf('--no-' + npmargs[i]) !== -1) {
	process.argv.push('--no-' + npmargs[i])
	}
	}
	if ((i = npmArgv.indexOf('--download')) !== -1) {
	process.argv.push(npmArgv[i], npmArgv[i + 1])
	}
	} catch (e) { }

And move this logic accordingly:

prebuild-install/rc.js

Lines 32 to 33 in ba21172

	var sourceBuild = env.npm_config_build_from_source
	var buildFromSource = sourceBuild === pkg.name || (sourceBuild === true || sourceBuild === 'true')

But we can move those tasks to a follow-up PR, because it's about a separate feature. Before that, perhaps we can change (some of) the rc tests to functional tests - i.e. running npm install on a mock package.

[adipascu]

@vweevers how can I help you merge this?

[vweevers]

I need some more eyes on this.

[vweevers]

5.3.0

[adipascu]

Thanks guys, nice working with you.