anchor.diff:            '_dartpadsupportservices/v1/storeGist', json);
         expect(postResponse.status, 400);
       });
  +
  +    test('Retrieve gist failure', () async {
  +      var response = await _sendGetRequest(
  +          '_dartpadsupportservices/v1/getUnusedMappingId');
  +      String gistId = 'testretrieve';
  +      expect(response.status, 200);
  +      var data = JSON.decode(UTF8.decode(await response.body.first));
  +      expect(data['uuid'], isNotNull);
  +      var json = {'gistId':gistId, 'internalId':data['uuid']};
  +      var postResponse = await _sendPostRequest(
  +          '_dartpadsupportservices/v1/storeGist', json);
  +      expect(postResponse.status, 200);
  +      var postData = JSON.decode(UTF8.decode(await postResponse.body.first));
  +      expect(postData['uuid'], gistId);
  +      var getResponse = await _sendGetRequest(
  +          '_dartpadsupportservices/v1/retrieveGist', 'id=${data['uuid']}');
  +      expect(getResponse.status, 200);
  +      var getData = JSON.decode(UTF8.decode(await getResponse.body.first));
  +      expect(getData['uuid'], gistId);
  +    });
  +
  +    test('Retrieve gist failure', () async {
  +      var response = await _sendGetRequest(
  +          '_dartpadsupportservices/v1/getUnusedMappingId');
  +      expect(response.status, 200);
  +      expect(data['uuid'], isNotNull);
  +      var getResponse = await _sendGetRequest(
  +          '_dartpadsupportservices/v1/retrieveGist', 'id=${data['uuid']}');
  +      expect(getResponse.status, 400);
  +    });
     });
   }
  
positive.code:           '_dartpadsupportservices/v1/getUnusedMappingId');
        expect(response.status, 200);
        var data = JSON.decode(UTF8.decode(await response.body.first));
        expect(data['uuid'] != null, true);
        var responseTwo = await _sendGetRequest(
            '_dartpadsupportservices/v1/getUnusedMappingId');
        expect(responseTwo.status, 200);
  
negative.code:       String gistId = 'teststore';
        expect(response.status, 200);
        var data = JSON.decode(UTF8.decode(await response.body.first));
        expect(data['uuid'], isNotNull);
        var json = {'gistId':gistId, 'internalId':data['uuid']};
        var postResponse = await _sendPostRequest(
            '_dartpadsupportservices/v1/storeGist', json);
  