anchor.diff:      Compiler compiler;
   
       setUp(() {
  -      return Compiler.createCompiler().then((c) {
  +      return Compiler.createCompiler(new _MockContentsProvider()).then((c) {
           compiler = c;
         });
       });
  
positive.code:     });
    });
  }
  
negative.code: // license that can be found in the LICENSE file.
  
  library spark.compiler_test;
  
  import 'dart:async';
  
  import 'package:unittest/unittest.dart';
  
  