anchor.diff:  
     Future<LibraryElement> resolveGeneratedLibrary(
         InMemoryAssetWriter writer) async {
  -    var rendererAsset = AssetId.parse('foo|lib/foo.renderers.dart');
  +    var rendererAsset = AssetId('foo', 'lib/foo.renderers.dart');
       var writtenStrings = writer.assets
           .map((id, content) => MapEntry(id.toString(), utf8.decode(content)));
       return await resolveSources(writtenStrings,
  
positive.code: class Baz {}
  ''');
        renderersLibrary = await resolveGeneratedLibrary(writer);
        var rendererAsset = AssetId.parse('foo|lib/foo.renderers.dart');
        generatedContent = utf8.decode(writer.assets[rendererAsset]);
      });
  
  
negative.code: library foo;
  import 'package:mustachio/annotations.dart';
  ''');
        var rendererAsset = AssetId('foo', 'lib/foo.renderers.dart');
        generatedContent = utf8.decode(writer.assets[rendererAsset]);
      });
  
  