### Question:
BatchedMetricsJSONOutputSerializer extends JSONBasicRollupsOutputSerializer implements BatchedMetricsOutputSerializer<JSONObject> { @Override public JSONObject transformRollupData(Map<Locator, MetricData> metricData, Set<MetricStat> filterStats) throws SerializationException { final JSONObject globalJSON = new JSONObject(); final JSONArray metricsArray = new JSONArray(); for (Map.Entry<Locator, MetricData> one : metricData.entrySet()) { final JSONObject singleMetricJSON = new JSONObject(); singleMetricJSON.put("metric", one.getKey().getMetricName()); singleMetricJSON.put("unit", one.getValue().getUnit() == null ? Util.UNKNOWN : one.getValue().getUnit()); singleMetricJSON.put("type", one.getValue().getType()); Set<MetricStat> oneFilterStats = fixFilterStats(one.getValue(), filterStats); JSONArray values = transformDataToJSONArray(one.getValue(), oneFilterStats); singleMetricJSON.put("data", values); metricsArray.add(singleMetricJSON); } globalJSON.put("metrics", metricsArray); return globalJSON; }  @Override JSONObject transformRollupData(Map<Locator, MetricData> metricData, Set<MetricStat> filterStats);  }### Answer:
@Test public void testBatchedMetricsSerialization() throws Exception { final BatchedMetricsJSONOutputSerializer serializer = new BatchedMetricsJSONOutputSerializer(); final Map<Locator, MetricData> metrics = new HashMap<Locator, MetricData>(); for (int i = 0; i < 2; i++) { final MetricData metricData = new MetricData(FakeMetricDataGenerator.generateFakeRollupPoints(), "unknown"); metrics.put(Locator.createLocatorFromPathComponents(tenantId, String.valueOf(i)), metricData); } JSONObject jsonMetrics = serializer.transformRollupData(metrics, filterStats); Assert.assertTrue(jsonMetrics.get("metrics") != null); JSONArray jsonMetricsArray = (JSONArray) jsonMetrics.get("metrics"); Iterator<JSONObject> metricsObjects = jsonMetricsArray.iterator(); Assert.assertTrue(metricsObjects.hasNext()); while (metricsObjects.hasNext()) { JSONObject singleMetricObject = metricsObjects.next(); Assert.assertTrue(singleMetricObject.get("unit").equals("unknown")); Assert.assertTrue(singleMetricObject.get("type").equals("number")); JSONArray data = (JSONArray) singleMetricObject.get("data"); Assert.assertTrue(data != null); } }