anchor.diff:  String _test_package = 'ddc_modular_test';
   
   Uri sdkRoot = Platform.script.resolve("../../../");
  +bool _nnbd = false;
   Options _options;
   String _dartdevcScript;
   String _buildSdkScript;
  
positive.code:             sdkRoot.toFilePath(),
              _sdkDevRuntime,
              'patched_sdk',
              if (nnbd) 'sdk_nnbd'
            ],
            root.toFilePath());
        _checkExitCode(result, this, module);
  
negative.code: 
      ProcessResult result;
  
      _nnbd = flags.contains('non-nullable');
      bool allowErrors = _nnbd && _nnbdOptOut.contains(module.name);
  
      if (module.isSdk) {
        assert(transitiveDependencies.isEmpty);
  