Fix gulp script to change version in the correct file

Command `gulp set --version <VERSION>` was meant to change version in
`version.js` which is later used in driver's user agent. However it tried to
modify `package.json` file instead of `version.js`.

This commit makes it operate on the correct file.

Author: lutovich

gulpfile.babel.js

@@ -47,6 +47,7 @@ var merge = require('merge-stream');
 var install = require("gulp-install");
 var os = require('os');
 var file = require('gulp-file');
+var semver = require('semver');
 
 gulp.task('default', ["test"]);
 
@@ -225,8 +226,13 @@ gulp.task('set', function() {
   // Get the --version arg from command line
   var version = minimist(process.argv.slice(2), { string: 'version' }).version;
 
+  if (!semver.valid(version)) {
+      throw 'Invalid version "' + version + '"';
+  }
+
   // Change the version in relevant files
-  return gulp.src(['package.json'], {base: "./"})
+  var versionFile = path.join('src', 'version.js');
+  return gulp.src([versionFile], {base: "./"})
       .pipe(replace('0.0.0-dev', version))
       .pipe(gulp.dest('./'));
 

package.json

@@ -52,6 +52,7 @@
     "minimist": "^1.2.0",
     "phantomjs-prebuilt": "^2.1.7 ",
     "run-sequence": "^1.1.4",
+    "semver": "^5.3.0",
     "through2": "~2.0.0",
     "vinyl-buffer": "^1.0.0",
     "vinyl-source-stream": "^1.1.0"