Set the correct content type for gzipped files with the .gz ext

Using the gzip plugin it's possible to specify a `keep` option
which will maintain both the original uncompressed file and save
the gzipped version with a `.gz` suffix. Amazon S3 does not detect
content type or encoding so this is all managed in this plugin via
the mime package. The default mime type is `application/octet-stream`
which is exactly what is detected for a `.gz` files. Uploading
`.js.gz` and `.css.gz` files without their correct content types
blows up some browsers with syntax errors (e.g. Safari)

This PR makes the uploader a little smarter. If we detect a file is
gzipped and has a `.gz` extension we strip the extension and look for
the non-gzipped file in the file path list. If it's found, we'll do
a mime lookup for the non-gzipped file and use _that_ content type
and encoding instead. If a non-gzipped counterpart isn't found we
will still upload the gzipped file as an `application/octet-stream`
so this shouldn't break any valid gzip assets that aren't compressed
as part of the gzip plugin in the pipeline.

Author: dannyfallon

lib/s3.js

@@ -91,6 +91,14 @@ module.exports = CoreObject.extend({
       var key         = prefix === '' ? filePath : [prefix, filePath].join('/');
       var isGzipped   = gzippedFilePaths.indexOf(filePath) !== -1;
 
+      if (isGzipped && path.extname(basePath) === '.gz') {
+        var basePathUncompressed = path.basename(basePath, '.gz');
+        if (filePaths.indexOf(basePathUncompressed) !== -1) {
+          contentType = mime.lookup(basePathUncompressed);
+          encoding    = mime.charsets.lookup(contentType);
+        }
+      }
+
       if (encoding) {
         contentType += '; charset=';
         contentType += encoding.toLowerCase();

tests/fixtures/dist/app.css.gz

@@ -110,6 +110,35 @@ describe('s3', function() {
             assert.equal(s3Params.ContentType, 'text/css; charset=utf-8');
             assert.equal(s3Params.Key, 'js-app/app.css');
             assert.equal(s3Params.CacheControl, 'max-age=63072000, public');
+            assert.isUndefined(s3Params.ContentEncoding);
+            assert.deepEqual(s3Params.Expires, new Date('2030'));
+          });
+      });
+
+      it('sends the correct content type params for gzipped files with .gz extension', function() {
+        var s3Params;
+        s3Client.putObject = function(params, cb) {
+          s3Params = params;
+          cb();
+        };
+
+        var options = {
+          filePaths: ['app.css', 'app.css.gz'],
+          gzippedFilePaths: ['app.css.gz'],
+          cwd: process.cwd() + '/tests/fixtures/dist',
+          prefix: 'js-app',
+          acl: 'public-read',
+          bucket: 'some-bucket'
+        };
+
+        var promises = subject.upload(options);
+
+        return assert.isFulfilled(promises)
+          .then(function() {
+            assert.equal(s3Params.ContentType, 'text/css; charset=utf-8');
+            assert.equal(s3Params.Key, 'js-app/app.css.gz');
+            assert.equal(s3Params.CacheControl, 'max-age=63072000, public');
+            assert.equal(s3Params.ContentEncoding, 'gzip');
             assert.deepEqual(s3Params.Expires, new Date('2030'));
           });
       });