anchor.diff:  abstract class _AstResynthesizeTestMixin
       implements _AstResynthesizeTestMixinInterface {
     final Set<Source> serializedSources = new Set<Source>();
  -  final PackageBundleAssembler bundleAssembler = new PackageBundleAssembler();
  +  PackageBundleAssembler bundleAssembler = new PackageBundleAssembler();
     final Map<String, UnlinkedUnitBuilder> uriToUnit =
         <String, UnlinkedUnitBuilder>{};
   
  
positive.code:     });
    }
  
    void _serializeLibrary(Source librarySource) {
      if (librarySource.isInSystemLibrary) {
        return;
  
negative.code:   @failingTest
    void test_constructors_inferFromArguments_redirectingFactory() {
      super.test_constructors_inferFromArguments_redirectingFactory();
    }
  
    @override
  