An alternate implementation that throws errors when the underlying implementation doesn’t support callbacks.

Author: whitingj

index.js

@@ -36,7 +36,6 @@ module.exports.filter = shouldCompress
  */
 
 var cacheControlNoTransformRegExp = /(?:^|,)\s*?no-transform\s*?(?:,|$)/
-var nodeHasCallbacks = (http.OutgoingMessage.prototype.write.length === 3 && http.OutgoingMessage.prototype.end.length === 3)
 
 /**
  * Compress response data with gzip / deflate.
@@ -67,6 +66,9 @@ function compression (options) {
     var _on = res.on
     var _write = res.write
 
+    var writeHasCallback = (_write.length == 3)
+    var endHasCallback = (_end.length == 3)
+
     // flush
     res.flush = function flush () {
       if (stream) {
@@ -81,20 +83,28 @@ function compression (options) {
         return false
       }
 
+      if (!writeHasCallback && cb !== undefined) {
+        throw new Error("compression, request.write does not support callback")
+      }
+
       if (!this._header) {
         this._implicitHeader()
       }
 
       return stream
-        ? stream.write(new Buffer(chunk, encoding), nodeHasCallbacks ? cb : undefined)
-        : _write.call(this, chunk, encoding, nodeHasCallbacks ? cb : undefined)
+        ? stream.write(new Buffer(chunk, encoding), cb)
+        : _write.call(this, chunk, encoding, cb)
     }
 
     res.end = function end (chunk, encoding, cb) {
       if (ended) {
         return false
       }
 
+      if (!endHasCallback && cb !== undefined) {
+        throw new Error("compression, request.end does not support callback")
+      }
+
       if (!this._header) {
         // estimate the length
         if (!this.getHeader('Content-Length')) {
@@ -105,16 +115,16 @@ function compression (options) {
       }
 
       if (!stream) {
-        return _end.call(this, chunk, encoding, nodeHasCallbacks ? cb : undefined)
+        return _end.call(this, chunk, encoding, cb)
       }
 
       // mark ended
       ended = true
 
       // write Buffer for Node.js 0.8
       return chunk
-        ? stream.end(new Buffer(chunk, encoding), nodeHasCallbacks ? cb : undefined)
-        : stream.end(null, null, nodeHasCallbacks ? cb : undefined)
+        ? stream.end(new Buffer(chunk, encoding), cb)
+        : stream.end(null, null, cb)
     }
 
     res.on = function on (type, listener) {

test/compression.js

@@ -681,18 +681,44 @@ describe('compression()', function () {
     it('should call the passed callbacks in the order passed when compressing', function (done) {
       var hasCallbacks = false
       var callbackOutput = []
+      var errorsCaught = 0
       var server = createServer(null, function (req, res) {
         hasCallbacks = (http.OutgoingMessage.prototype.write.length === 3 && http.OutgoingMessage.prototype.end.length === 3)
         res.setHeader('Content-Type', 'text/plain')
-        res.write('Hello', null, function () {
-          callbackOutput.push(0)
-        })
-        res.write(' World', null, function () {
-          callbackOutput.push(1)
-        })
-        res.end(null, null, function () {
-          callbackOutput.push(2)
-        })
+        try {
+          res.write('Hello', null, function () {
+            callbackOutput.push(0)
+          })
+        } catch(error) {
+          errorsCaught++
+          if (hasCallbacks || error.message !== "compression, request.write does not support callback") {
+            throw error;
+          }
+          res.write('Hello');
+        }
+        try {
+          res.write(' World', null, function () {
+            callbackOutput.push(1)
+          })
+        } catch(error) {
+          errorsCaught++
+          if (hasCallbacks || error.message !== "compression, request.write does not support callback") {
+            throw error;
+          }
+          res.write(' World')
+        }
+        try {
+          res.end(null, null, function () {
+            callbackOutput.push(2)
+          })
+        } catch(error) {
+          errorsCaught++
+          console.log(error)
+          if (hasCallbacks || error.message !== "compression, request.end does not support callback") {
+            throw error;
+          }
+          res.end()
+        }
       })
 
       request(server)
@@ -709,6 +735,7 @@ describe('compression()', function () {
         } else {
           // nodejs 0.10 zlib has callbacks but OutgoingMessage doesn't, assert that no callbacks were made
           assert.equal(callbackOutput.length, 0)
+          assert.equal(errorsCaught, 3)
         }
         done()
       })
@@ -717,19 +744,44 @@ describe('compression()', function () {
     it('should call the passed callbacks in the order passed when not compressing', function (done) {
       var hasCallbacks = false
       var callbackOutput = []
+      var errorsCaught = 0
       var server = createServer(null, function (req, res) {
         hasCallbacks = (http.OutgoingMessage.prototype.write.length === 3 && http.OutgoingMessage.prototype.end.length === 3)
         res.setHeader('Cache-Control', 'no-transform')
         res.setHeader('Content-Type', 'text/plain')
-        res.write('hello,', null, function () {
-          callbackOutput.push(0)
-        })
-        res.write(' world', null, function () {
-          callbackOutput.push(1)
-        })
-        res.end(null, null, function () {
-          callbackOutput.push(2)
-        })
+        try {
+          res.write('hello,', null, function () {
+            callbackOutput.push(0)
+          })
+        } catch(error) {
+          errorsCaught++
+          if (hasCallbacks || error.message !== "compression, request.write does not support callback") {
+            throw error;
+          }
+          res.write('Hello');
+        }
+        try {
+          res.write(' world', null, function () {
+            callbackOutput.push(1)
+          })
+        } catch(error) {
+          errorsCaught++
+          if (hasCallbacks || error.message !== "compression, request.write does not support callback") {
+            throw error;
+          }
+          res.write(' world');
+        }
+        try {
+          res.end(null, null, function () {
+            callbackOutput.push(2)
+          })
+        } catch(error) {
+          errorsCaught++
+          if (hasCallbacks || error.message !== "compression, request.end does not support callback") {
+            throw error;
+          }
+          res.end();
+        }
       })
 
       request(server)
@@ -746,6 +798,7 @@ describe('compression()', function () {
           assert.deepEqual(callbackOutput, [0, 1, 2])
         } else {
           assert.equal(callbackOutput.length, 0)
+          assert.equal(errorsCaught, 3)
         }
         done()
       })