anchor.diff:        accessLocation = 2;
       });
   
  -    var client = const Pipeline()
  +    const Pipeline()
           .addMiddleware(middlewareA)
           .addMiddleware(middlewareB)
           .addClient(new Client.handler((request) async => null, onClose: () {
             expect(accessLocation, 2);
             accessLocation = 3;
  -        }));
  +        }))
  +          ..close();
   
  -    client.close();
       expect(accessLocation, 3);
     });
   }
  
positive.code:   });
  
    test('Pipeline calls close on all middleware', () {
      int accessLocation = 0;
  
      var middlewareA = createMiddleware(onClose: () {
        expect(accessLocation, 0);
  
negative.code:   });
  
    test('Pipeline can be used as middleware', () async {
      var accessLocation = 0;
  
      var middlewareA = createMiddleware(requestHandler: (request) async {
        expect(accessLocation, 0);
  