From 5d540faec4a99cc168a5a42d549fb08aa726051a Mon Sep 17 00:00:00 2001
From: Mark Oswald <markoswald123@gmail.com>
Date: Wed, 6 Jul 2016 22:46:55 +0200
Subject: [PATCH] refactor as middleware function and add test

---
 .../src/Server/__tests__/Server-test.js       | 13 ++++++
 packager/react-packager/src/Server/index.js   | 45 +++++++++----------
 2 files changed, 34 insertions(+), 24 deletions(-)

diff --git a/packager/react-packager/src/Server/__tests__/Server-test.js b/packager/react-packager/src/Server/__tests__/Server-test.js
index c54e503d171e21..060eb8d2d08f14 100644
--- a/packager/react-packager/src/Server/__tests__/Server-test.js
+++ b/packager/react-packager/src/Server/__tests__/Server-test.js
@@ -349,6 +349,19 @@ describe('processRequest', () => {
       expect(AssetServer.prototype.get).toBeCalledWith('imgs/a.png', 'ios');
       expect(res.end).toBeCalledWith('i am image');
     });
+
+    it('should serve range request', () => {
+      const req = {url: '/assets/imgs/a.png?platform=ios', headers: {range: 'bytes=0-3'}};
+      const res = {end: jest.fn(), writeHead: jest.fn()};
+      const mockData = new Buffer('i am image');
+
+      AssetServer.prototype.get.mockImpl(() => Promise.resolve(mockData));
+
+      server.processRequest(req, res);
+      jest.runAllTimers();
+      expect(AssetServer.prototype.get).toBeCalledWith('imgs/a.png', 'ios');
+      expect(res.end).toBeCalledWith(mockData.slice(0, 3));
+    });
   });
 
   describe('buildbundle(options)', () => {
diff --git a/packager/react-packager/src/Server/index.js b/packager/react-packager/src/Server/index.js
index 3cab1e5c948802..1e2d4b1013c29b 100644
--- a/packager/react-packager/src/Server/index.js
+++ b/packager/react-packager/src/Server/index.js
@@ -169,8 +169,6 @@ const dependencyOpts = declareOpts({
   },
 });
 
-const isRangeRequest = (req) => req.headers && req.headers.range;
-
 class Server {
   constructor(options) {
     const opts = validateOpts(options);
@@ -399,34 +397,33 @@ class Server {
     });
   }
 
+  _rangeRequestMiddleware(req, res, data, assetPath) {
+    if (req.headers && req.headers.range) {
+      let [rangeStart, rangeEnd] = req.headers.range.replace(/bytes=/, '').split('-');
+      let dataStart = parseInt(rangeStart, 10);
+      let dataEnd = rangeEnd ? parseInt(rangeEnd, 10) : data.length - 1;
+      let chunksize = (dataEnd - dataStart) + 1;
+
+      res.writeHead(206, {
+        'Accept-Ranges': 'bytes',
+        'Content-Length': chunksize,
+        'Content-Range': `bytes ${dataStart}-${dataEnd}/${data.length}`,
+        'Content-Type': mime.lookup(path.basename(assetPath[1]))
+      });
+
+      return data.slice(dataStart, dataEnd);
+    }
+
+    return data;
+  }
+
   _processAssetsRequest(req, res) {
     const urlObj = url.parse(req.url, true);
     const assetPath = urlObj.pathname.match(/^\/assets\/(.+)$/);
     const assetEvent = Activity.startEvent(`processing asset request ${assetPath[1]}`);
     this._assetServer.get(assetPath[1], urlObj.query.platform)
       .then(
-        data => {
-          if (isRangeRequest(req)) {
-            let [rangeStart, rangeEnd] = req.headers.range.replace(/bytes=/, '').split('-');
-            let dataStart = parseInt(rangeStart, 10);
-            let dataEnd = rangeEnd ? parseInt(rangeEnd, 10) : data.length - 1;
-            let chunksize = (dataEnd - dataStart) + 1;
-
-            res.writeHead(206, {
-              'Accept-Ranges': 'bytes',
-              'Content-Length': chunksize,
-              'Content-Range': `bytes ${dataStart}-${dataEnd}/${data.length}`,
-              'Content-Type': mime.lookup(path.basename(assetPath[1]))
-            });
-
-            let output = new Buffer(chunksize);
-            data.copy(output, 0, dataStart, dataEnd);
-
-            res.end(output);
-          } else {
-            res.end(data);
-          }
-        },
+        data => res.end(this._rangeRequestMiddleware(req, res, data, assetPath)),
         error => {
           console.error(error.stack);
           res.writeHead('404');