### Question:
KafkaPartitionMetricSampleAggregator extends MetricSampleAggregator<String, PartitionEntity> { public SortedMap<Long, Float> validPartitionRatioByWindows(Cluster cluster) { AggregationOptions<String, PartitionEntity> options = new AggregationOptions<>(0.0, 0.0, 1, _maxAllowedExtrapolationsPerPartition, allPartitions(cluster), AggregationOptions.Granularity.ENTITY, true); MetricSampleCompleteness<String, PartitionEntity> completeness = completeness(-1, Long.MAX_VALUE, options); return windowIndicesToWindows(completeness.validEntityRatioWithGroupGranularityByWindowIndex(), _windowMs); } KafkaPartitionMetricSampleAggregator(KafkaCruiseControlConfig config, Metadata metadata); boolean addSample(PartitionMetricSample sample); boolean addSample(PartitionMetricSample sample, boolean leaderValidation); MetricSampleAggregationResult<String, PartitionEntity> aggregate(Cluster cluster,
                                                                          long now,
                                                                          OperationProgress operationProgress); MetricSampleAggregationResult<String, PartitionEntity> aggregate(Cluster cluster,
                                                                          long from,
                                                                          long to,
                                                                          ModelCompletenessRequirements requirements,
                                                                          OperationProgress operationProgress); MetricSampleCompleteness<String, PartitionEntity> completeness(Cluster cluster,
                                                                        long from,
                                                                        long to,
                                                                        ModelCompletenessRequirements requirements); SortedSet<Long> validWindows(Cluster cluster, double minMonitoredPartitionsPercentage); double monitoredPercentage(Cluster cluster); SortedMap<Long, Float> validPartitionRatioByWindows(Cluster cluster);  }### Answer:
@Test public void testMonitoredPercentagesByWindows() { TestContext ctx = setupScenario1(); KafkaPartitionMetricSampleAggregator aggregator = ctx.aggregator(); MetadataClient.ClusterAndGeneration clusterAndGeneration = ctx.clusterAndGeneration(0); Map<Long, Float> percentages = aggregator.validPartitionRatioByWindows(clusterAndGeneration.cluster()); assertEquals(NUM_WINDOWS, percentages.size()); for (Map.Entry<Long, Float> entry : percentages.entrySet()) { assertEquals(1.0, entry.getValue(), 0.01); } ctx = setupScenario2(); aggregator = ctx.aggregator(); clusterAndGeneration = ctx.clusterAndGeneration(0); percentages = aggregator.validPartitionRatioByWindows(clusterAndGeneration.cluster()); assertEquals(NUM_WINDOWS, percentages.size()); for (Map.Entry<Long, Float> entry : percentages.entrySet()) { long window = entry.getKey(); if (window == 6000 || window == 7000 || window == 20000) { assertEquals(0.5, entry.getValue(), 0.01); } else { assertEquals(1.0, entry.getValue(), 0.01); } } ctx = setupScenario3(); aggregator = ctx.aggregator(); clusterAndGeneration = ctx.clusterAndGeneration(0); percentages = aggregator.validPartitionRatioByWindows(clusterAndGeneration.cluster()); assertEquals(NUM_WINDOWS, percentages.size()); for (Map.Entry<Long, Float> entry : percentages.entrySet()) { long window = entry.getKey(); if (window == 6000 || window == 7000 || window == 18000 || window == 19000) { assertEquals((double) 4 / 6, entry.getValue(), 0.01); } else { assertEquals(1.0, entry.getValue(), 0.01); } } ctx = setupScenario4(); aggregator = ctx.aggregator(); clusterAndGeneration = ctx.clusterAndGeneration(0); percentages = aggregator.validPartitionRatioByWindows(clusterAndGeneration.cluster()); assertEquals(NUM_WINDOWS, percentages.size()); for (Map.Entry<Long, Float> entry : percentages.entrySet()) { long window = entry.getKey(); if (window == 6000 || window == 7000) { assertEquals((double) 2 / 6, entry.getValue(), 0.01); } else { assertEquals((double) 4 / 6, entry.getValue(), 0.01); } } }