anchor.diff:  class MockHttpServer extends Mock implements HttpServer {}
   class MockRouter extends Mock implements Router {}
   class MockRequestNavigator extends Mock implements RequestNavigator {}
  -class MockHMAC extends Mock implements HMAC {}
  +class MockHMAC extends Mock implements HMAC {
  +  var listOfInt = [];
  +  MockHMAC();
  +  add(List<int> val) => listOfInt.addAll(val);
  +  close() => listOfInt.map((int i) => i+10).toList();
  +  verify(List<int> digest) {
  +    if (digest.length != listOfInt.length) return false;
  +      for(int i = 0 ; i < digest.length; i++)
  +        if (digest[i] != listOfInt[i]+10) return false;
  +    return true;
  +  }
  +}
  +
   class HttpBodyMock extends Mock implements HttpBody {}
   
   class HttpResponseMock extends Mock implements HttpResponse{
  
positive.code:     MockHttpServer server;
      MockRequestNavigator requestNavigator;
      MockRouter router;
      MockHMAC hmac;
      HttpBodyHandlerMock httpBodyHandler;
  
      setUp(() {
        server = new MockHttpServer();
        router = new MockRouter();
        requestNavigator = new MockRequestNavigator();
        hmac = new MockHMAC();
        httpBodyHandler = new HttpBodyHandlerMock();
  
        backend = new Backend.config(server, router, requestNavigator, hmac, httpBodyHandler.processRequest);
      });
  
      test('addRoute', () {
  
negative.code:       });
      });
  
      test('signing and verifing message', (){
        //given
        var msg = 'random msg';
  
        //when
        var signature = backend.sign(msg);
        var badSignature = signature.toList()..add(5);
  
        //then
        expect(backend.verifySignature(msg, signature), isTrue);
        expect(backend.verifySignature(msg, badSignature), isFalse);
        expect(backend.verifySignature('another msg', signature), isFalse);
      });
  
    });
  }
  
  