Don't log stack trace for a bad package URL in a source file.

pkg/analyzer/test/generated/source_factory_test.dart

 // Copyright (c) 2015, 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 analyzer.test.generated.test.generated.source_factory;
 
 import 'dart:convert';
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/source/package_map_resolver.dart';
+import 'package:analyzer/src/generated/engine.dart' show AnalysisEngine, Logger;
 import 'package:analyzer/src/generated/java_core.dart';
 import 'package:analyzer/src/generated/java_engine_io.dart';
 import 'package:analyzer/src/generated/java_io.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:analyzer/src/generated/utilities_dart.dart' as utils;
 import 'package:package_config/packages.dart';
 import 'package:package_config/packages_file.dart' as pkgfile show parse;
 import 'package:package_config/src/packages_impl.dart';
 import 'package:path/path.dart';
@@ skipping 35 matching lines @@
       {String uri,
       String config,
       Source containingSource,
       UriResolver customResolver}) {
     Packages packages = createPackageMap(baseUri, config);
     List<UriResolver> resolvers = testResolvers.toList();
     if (customResolver != null) {
       resolvers.add(customResolver);
     }
     SourceFactory factory = new SourceFactory(resolvers, packages);
-    Source source = factory.resolveUri(containingSource, uri);
-    return source != null ? source.fullName : null;
+
+    expect(AnalysisEngine.instance.logger, Logger.NULL);
+    var logger = new TestLogger();
+    AnalysisEngine.instance.logger = logger;
+    try {
+      Source source = factory.resolveUri(containingSource, uri);
+      expect(logger.log, []);
+      return source != null ? source.fullName : null;
+    } finally {
+      AnalysisEngine.instance.logger = Logger.NULL;
+    }
   }
 
   Uri restorePackageUri(
       {Source source, String config, UriResolver customResolver}) {
     Packages packages = createPackageMap(baseUri, config);
     List<UriResolver> resolvers = testResolvers.toList();
     if (customResolver != null) {
       resolvers.add(customResolver);
     }
     SourceFactory factory = new SourceFactory(resolvers, packages);
@@ skipping 36 matching lines @@
           expect(uri, isNull);
         });
         test('Non-package URI', () {
           var testResolver = new CustomUriResolver(uriPath: 'test_uri');
           String uri = resolvePackageUri(
               config: 'unittest:/home/somebody/.pub/cache/unittest-0.9.9/lib/',
               uri: 'custom:custom.dart',
               customResolver: testResolver);
           expect(uri, testResolver.uriPath);
         });
+        test('Bad package URI', () {
+          String uri = resolvePackageUri(config: '', uri: 'package:foo');
+          expect(uri, isNull);
+        });
         test('Invalid URI', () {
           // TODO(pquitslund): fix clients to handle errors appropriately
           //   CLI: print message 'invalid package file format'
           //   SERVER: best case tell user somehow and recover...
           expect(
               () => resolvePackageUri(
                   config: 'foo:<:&%>', uri: 'package:foo/bar.dart'),
               throwsA(new isInstanceOf('FormatException')));
         });
         test('Valid URI that cannot be further resolved', () {
@@ skipping 208 matching lines @@
   UriResolver_SourceFactoryTest_test_fromEncoding_valid(this.encoding);
 
   @override
   Source resolveAbsolute(Uri uri, [Uri actualUri]) {
     if (uri.toString() == encoding) {
       return new TestSource();
     }
     return null;
   }
 }