Support npm_config_build_from_source (#99)

rc.js

@@ -29,6 +29,8 @@ if (env.npm_config_argv) {
 // Get the configuration
 module.exports = function (pkg) {
   var pkgConf = pkg.config || {}
+  var sourceBuild = env.npm_config_build_from_source
+  var buildFromSource = sourceBuild === pkg.name || sourceBuild === 'true'
   var rc = require('rc')('prebuild-install', {
     target: pkgConf.target || env.npm_config_target || process.versions.node,
     runtime: pkgConf.runtime || env.npm_config_runtime || 'node',
@@ -39,7 +41,7 @@ module.exports = function (pkg) {
     force: false,
     verbose: false,
     prebuild: true,
-    compile: false,
+    compile: buildFromSource,
     path: '.',
     proxy: env.npm_config_proxy || env['HTTP_PROXY'],
     'https-proxy': env.npm_config_https_proxy || env['HTTPS_PROXY'],

test/rc-test.js

@@ -68,7 +68,8 @@ test('npm_config_* are passed on from environment into rc', function (t) {
     npm_config_local_address: 'LOCAL_ADDRESS',
     npm_config_target: '1.4.0',
     npm_config_runtime: 'electron',
-    npm_config_platform: 'PLATFORM'
+    npm_config_platform: 'PLATFORM',
+    npm_config_build_from_source: 'true'
   }
   runRc(t, '', env, function (rc) {
     t.equal(rc.proxy, 'PROXY', 'proxy is set')
@@ -77,6 +78,7 @@ test('npm_config_* are passed on from environment into rc', function (t) {
     t.equal(rc.target, '1.4.0', 'target is set')
     t.equal(rc.runtime, 'electron', 'runtime is set')
     t.equal(rc.platform, 'PLATFORM', 'platform is set')
+    t.equal(rc.compile, true, 'build-from-source is set')
     t.end()
   })
 })