anchor.diff:  
     Future<void> test_addInsertion() async {
       var builder = ChangeBuilderImpl();
  -    await builder.addFileEdit(path, (FileEditBuilder builder) {
  -      builder.addInsertion(10, (EditBuilder builder) {
  +    await builder.addGenericFileEdit(path, (builder) {
  +      builder.addInsertion(10, (builder) {
           expect(builder, isNotNull);
         });
       });
  
positive.code:   Future<void> test_addSuggestion_zeroLength() async {
      var groupName = 'a';
      var builder = ChangeBuilderImpl();
      await builder.addFileEdit(path, (FileEditBuilder builder) {
        builder.addInsertion(10, (EditBuilder builder) {
          builder.addLinkedEdit(groupName, (LinkedEditBuilder builder) {
            builder.addSuggestion(LinkedEditSuggestionKind.TYPE, 'A');
          });
        });
  
negative.code:   Future<void> test_addLinkedPosition() async {
      var builder = ChangeBuilderImpl();
      var groupName = 'a';
      await builder.addGenericFileEdit(path, (builder) {
        builder.addLinkedPosition(SourceRange(3, 6), groupName);
      });
  
  