Handle synchronous asset load errors in barback.

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 127 matching lines @@
     ]});
 
     setAssetError("app|foo.txt");
     updateSources(["app|foo.txt"]);
     expectNoAsset("app|foo.txt");
     buildShouldFail([
       isAssetLoadException("app|foo.txt", isMockLoadException("app|foo.txt"))
     ]);
   });
 
+  test("a synchronous error loading an asset removes the asset from the graph",
+      () {
+    initGraph(["app|foo.txt"], {"app": [
+      // Have a dummy transformer so that barback at least tries to load the
+      // asset.
+      [new RewriteTransformer("a", "b")]
+    ]});
+
+    setAssetError("app|foo.txt", async: false);
+    updateSources(["app|foo.txt"]);
+    expectNoAsset("app|foo.txt");
+    buildShouldFail([
+      isAssetLoadException("app|foo.txt", isMockLoadException("app|foo.txt"))
+    ]);
+  });
+
   test("an asset isn't passed through a transformer with an error", () {
     initGraph(["app|foo.txt"], {"app": [[new BadTransformer([])]]});
 
     updateSources(["app|foo.txt"]);
     expectNoAsset("app|foo.txt");
     buildShouldFail([isTransformerException(equals(BadTransformer.ERROR))]);
   });
 
   test("a transformer that logs errors shouldn't produce output", () {
     initGraph(["app|foo.txt"], {"app": [
@@ skipping 30 matching lines @@
 
     updateSources(["app|foo.txt"]);
     expectNoAsset("app|foo.out");
     buildShouldFail([isMissingInputException("app|bar.inc")]);
 
     updateSources(["app|bar.inc"]);
     expectAsset("app|foo.out", "bar");
     buildShouldSucceed();
   });
 }