Fix reading msvs version on Windows (#2644)

* fix: fix reading msvs version on windows

Author: jgcook935

lib/configure.js

@@ -85,7 +85,7 @@ function configure (gyp, argv, callback) {
         'build dir', '"build" dir needed to be created?', isNew ? 'Yes' : 'No'
       )
       if (win) {
-        findVisualStudio(release.semver, gyp.opts.msvs_version,
+        findVisualStudio(release.semver, gyp.opts['msvs-version'],
           createConfigFile)
       } else {
         createPythonSymlink()

lib/node-gyp.js

@@ -60,7 +60,7 @@ proto.configDefs = {
   debug: Boolean, // 'build'
   directory: String, // bin
   make: String, // 'build'
-  msvs_version: String, // 'configure'
+  'msvs-version': String, // 'configure'
   ensure: Boolean, // 'install'
   solution: String, // 'build' (windows only)
   proxy: String, // 'install'

test/test-options.js

@@ -38,4 +38,13 @@ describe('options', function () {
 
     assert.strictEqual(g.opts['force-process-config'], 'true')
   })
+
+  it('options with msvs_version', () => {
+    process.env.npm_config_msvs_version = '2017'
+
+    const g = gyp()
+    g.parseArgv(['rebuild']) // Also sets opts.argv.
+
+    assert.strictEqual(g.opts['msvs-version'], '2017')
+  })
 })