Prefer gzip over deflate on the server

closes #26

Author: dougwilson

HISTORY.md

@@ -1,3 +1,9 @@
+unreleased
+==========
+
+  * Prefer `gzip` over `deflate` on the server
+    - Not all clients agree on what "deflate" coding means
+
 1.3.1 / 2015-01-31
 ==================
 

index.js

@@ -159,6 +159,11 @@ function compression(options) {
       var accept = accepts(req)
       var method = accept.encoding(['gzip', 'deflate', 'identity'])
 
+      // we really don't prefer deflate
+      if (method === 'deflate' && accept.encoding(['gzip'])) {
+        method = accept.encoding(['gzip', 'identity'])
+      }
+
       // negotiation failed
       if (!method || method === 'identity') {
         nocompress('not acceptable')

test/compression.js

@@ -7,18 +7,6 @@ var request = require('supertest');
 var compression = require('..');
 
 describe('compression()', function(){
-  it('should gzip files', function(done){
-    var server = createServer({ threshold: 0 }, function (req, res) {
-      res.setHeader('Content-Type', 'text/plain')
-      res.end('hello, world')
-    })
-
-    request(server)
-    .get('/')
-    .set('Accept-Encoding', 'gzip')
-    .expect('Content-Encoding', 'gzip', done)
-  })
-
   it('should skip HEAD', function(done){
     var server = createServer({ threshold: 0 }, function (req, res) {
       res.setHeader('Content-Type', 'text/plain')
@@ -394,6 +382,62 @@ describe('compression()', function(){
     })
   })
 
+  describe('when "Accept-Encoding: gzip"', function () {
+    it('should respond with gzip', function (done) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+      .get('/')
+      .set('Accept-Encoding', 'gzip')
+      .expect('Content-Encoding', 'gzip', done)
+    })
+  })
+
+  describe('when "Accept-Encoding: deflate"', function () {
+    it('should respond with deflate', function (done) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+      .get('/')
+      .set('Accept-Encoding', 'deflate')
+      .expect('Content-Encoding', 'deflate', done)
+    })
+  })
+
+  describe('when "Accept-Encoding: gzip, deflate"', function () {
+    it('should respond with gzip', function (done) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+      .get('/')
+      .set('Accept-Encoding', 'gzip, deflate')
+      .expect('Content-Encoding', 'gzip', done)
+    })
+  })
+
+  describe('when "Accept-Encoding: deflate, gzip"', function () {
+    it('should respond with gzip', function (done) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+      .get('/')
+      .set('Accept-Encoding', 'deflate, gzip')
+      .expect('Content-Encoding', 'gzip', done)
+    })
+  })
+
   describe('.filter', function () {
     it('should be a function', function () {
       assert.equal(typeof compression.filter, 'function')