anchor.diff:      return "// @dart = 2.9\n${beforePlug}${plug}${afterPlug}";
     }
   }
  +
  +class CompilerAndOptions {
  +  final TestCompiler compiler;
  +  final CompilerOptions options;
  +
  +  CompilerAndOptions(this.compiler, this.options);
  +}
  
positive.code:     helper.TestIncrementalCompiler compiler =
          new helper.TestIncrementalCompiler(options, testUri);
  
      return new TestCompiler._(testUri, fs, formattedErrors, formattedWarnings,
          formattedErrorsCodes, formattedWarningsCodes, compiler);
    }
  }
  
  
negative.code: import 'incremental_suite.dart' as helper;
  
  main() async {
    CompilerAndOptions compilerAndOptions = TestCompiler.initialize();
    TestCompiler compiler = compilerAndOptions.compiler;
    bool hasNewline = true;
    int numErrors = 0;
    List<String> errorSource = [];
  