Fix error handling bug in stream.pipe()

lib/stream.js

@@ -95,7 +95,7 @@ Stream.prototype.pipe = function(dest, options) {
   // don't leave dangling pipes when there are errors.
   function onerror(er) {
     cleanup();
-    if (this.listeners('error').length === 1) {
+    if (this.listeners('error').length === 0) {
       throw er; // Unhandled stream error in pipe.
     }
   }

test/simple/test-stream-pipe-error-handling.js

@@ -0,0 +1,58 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+var Stream = require('stream').Stream;
+
+(function testErrorListenerCatches() {
+  var source = new Stream();
+  var dest = new Stream();
+
+  source.pipe(dest);
+
+  var gotErr = null;
+  source.on('error', function(err) {
+    gotErr = err;
+  });
+
+  var err = new Error('This stream turned into bacon.');
+  source.emit('error', err);
+  assert.strictEqual(gotErr, err);
+})();
+
+(function testErrorWithoutListenerThrows() {
+  var source = new Stream();
+  var dest = new Stream();
+
+  source.pipe(dest);
+
+  var err = new Error('This stream turned into bacon.');
+
+  var gotErr = null;
+  try {
+    source.emit('error', err);
+  } catch (e) {
+    gotErr = e;
+  }
+
+  assert.strictEqual(gotErr, err);
+})();