Barback transforms now pass through the primary input by default.

pkg/barback/test/package_graph/errors_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library barback.test.package_graph.source_test;
 
 import 'package:barback/src/utils.dart';
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../utils.dart';
@@ skipping 96 matching lines @@
   test("catches transformer exceptions and reports them", () {
     initGraph(["app|foo.txt"], {"app": [
       [new BadTransformer(["app|foo.out"])]
     ]});
 
     updateSources(["app|foo.txt"]);
     expectNoAsset("app|foo.out");
     buildShouldFail([isTransformerException(equals(BadTransformer.ERROR))]);
   });
 
-  test("doesn't yield a source if a transform fails on it", () {
-    initGraph(["app|foo.txt"], {"app": [
-      [new BadTransformer(["app|foo.txt"])]
-    ]});
-
-    updateSources(["app|foo.txt"]);
-    expectNoAsset("app|foo.txt");
-  });
-
   test("catches errors even if nothing is waiting for process results", () {
     initGraph(["app|foo.txt"], {"app": [[new BadTransformer([])]]});
 
     updateSources(["app|foo.txt"]);
     // Note: No asset requests here.
     buildShouldFail([isTransformerException(equals(BadTransformer.ERROR))]);
   });
 
   test("discards outputs from failed transforms", () {
     initGraph(["app|foo.txt"], {"app": [
@@ skipping 188 matching lines @@
 
     updateSources(["app|foo.txt"]);
     expectAsset("app|foo.txt", "foo");
     buildShouldSucceed();
 
     updateSources(["app|foo.in"]);
     expectAsset("app|foo.txt", "foo");
     buildShouldFail([isAssetCollisionException("app|foo.txt")]);
   });
 }