Use underlying stream as event emitter

lib/AsyncWriter.js

@@ -13,7 +13,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-'use strict';
 function StringBuilder() {
     this.str = '';
 }
@@ -105,8 +104,6 @@ AsyncFragment.prototype = {
             // Make sure end is only called once by the user
             this.finished = true;
 
-
-
             if (this.ready) {
                 // There are no nested asynchronous fragments that are
                 // remaining and we are ready to be flushed then let's do it!
@@ -132,16 +129,12 @@ function AsyncWriter(writer, global) {
     this._isSync = false;
 
     if (!global.events) {
-        global.events = new EventEmitter();
+        // Use the underlying stream as the event emitter if available.
+        // Otherwise, create a new event emitter
+        global.events = writer && writer.on ? writer : new EventEmitter();
     }
 
     if (!global.async) {
-        if (writer && writer.end) {
-            this.on('end', function() {
-                writer.end();
-            });
-        }
-
         global.async = {
             remaining: 0,
             ended: false,
@@ -311,6 +304,12 @@ AsyncWriter.prototype = {
         return this;
     },
 
+    removeListener: function() {
+        var events = this.global.events;
+        events.removeListener.apply(events, arguments);
+        return this;
+    },
+
     pipe: function(stream) {
         this.stream.pipe(stream);
         return this;
@@ -376,7 +375,11 @@ AsyncWriter.prototype = {
             }
 
             if (async.remaining === 0) {
-                this.emit('end');
+                if (this.stream.end) {
+                    this.stream.end();
+                } else {
+                    this.emit('end');
+                }
             }
         }
     }

test/test.js

@@ -380,4 +380,34 @@ describe('async-writer' , function() {
             done();
         });
     });
+
+    it('should not crash the program if the underlying stream has an error listener', function(done) {
+        var stream = require('stream');
+        var PassThrough = stream.PassThrough;
+        var passthrough = new PassThrough();
+
+        passthrough.on('error', function(err) {
+            done();
+        });
+
+        var out = require('../').create(passthrough);
+        out.write('hello');
+        out.error('test');
+    });
+
+    it('should crash the program if the underlying stream does *not* have an error listener', function(done) {
+        var stream = require('stream');
+        var PassThrough = stream.PassThrough;
+        var passthrough = new PassThrough();
+
+        var out = require('../').create(passthrough);
+        out.write('hello');
+        try {
+            out.error('test');
+            done('uncaught exception expected');
+        } catch(e) {
+            done();
+        }
+
+    });
 });