anchor.diff:      final MockProcedure procedure = MockProcedure();
       final MockFunctionNode function = MockFunctionNode();
       final MockStatement statement = MockStatement();
  -    final Library library = Library(Uri.parse('package:some_package/src/blah.dart'));
  +    final Uri uri = Uri.parse('package:some_package/src/blah.dart');
  +    final Library library = Library(uri, fileUri: uri);
       when(procedure.function).thenReturn(function);
       when(procedure.name).thenReturn(Name('toString'));
       when(procedure.annotations).thenReturn(const <Expression>[]);
  
positive.code:     final MockProcedure procedure = MockProcedure();
      final MockFunctionNode function = MockFunctionNode();
      final MockStatement statement = MockStatement();
      final Library library = Library(Uri.parse('package:some_package/src/blah.dart'));
      when(procedure.function).thenReturn(function);
      when(procedure.name).thenReturn(Name('toString'));
      when(procedure.annotations).thenReturn(const <Expression>[]);
      when(procedure.enclosingLibrary).thenReturn(library);
      when(procedure.enclosingClass).thenReturn(Class(name: 'foo'));
      when(procedure.isAbstract).thenReturn(true);
      when(procedure.isStatic).thenReturn(false);
      when(function.body).thenReturn(statement);
  
negative.code:     final MockProcedure procedure = MockProcedure();
      final MockFunctionNode function = MockFunctionNode();
      final MockStatement statement = MockStatement();
      final Uri uri = Uri.parse('dart:ui');
      final Library library = Library(uri, fileUri: uri);
      final Name name = Name('toString');
      final Class annotation = Class(name: '_KeepToString', fileUri: uri)..parent = library;
  
      when(procedure.function).thenReturn(function);
      when(procedure.name).thenReturn(name);
  