### Question:
MetricSampleAggregator extends LongGenerationed { public Map<E, ValuesAndExtrapolations> peekCurrentWindow() { _windowRollingLock.lock(); try { Map<E, ValuesAndExtrapolations> result = new HashMap<>(); _rawMetrics.forEach((entity, rawMetric) -> { ValuesAndExtrapolations vae = rawMetric.peekCurrentWindow(_currentWindowIndex, _metricDef); SortedSet<Long> currentWindows = new TreeSet<>(Collections.singleton(_currentWindowIndex)); vae.setWindows(toWindows(currentWindows)); result.put(entity, vae); }); return result; } finally { _windowRollingLock.unlock(); } } MetricSampleAggregator(int numWindows,
                                long windowMs,
                                byte minSamplesPerWindow,
                                int completenessCacheSize,
                                MetricDef metricDef); boolean addSample(MetricSample<G, E> sample); MetricSampleAggregationResult<G, E> aggregate(long from, long to, AggregationOptions<G, E> options); Map<E, ValuesAndExtrapolations> peekCurrentWindow(); MetricSampleCompleteness<G, E> completeness(long from, long to, AggregationOptions<G, E> options); List<Long> availableWindows(); int numAvailableWindows(); int numAvailableWindows(long from, long to); List<Long> allWindows(); Long earliestWindow(); int numSamples(); void retainEntities(Set<E> entities); void removeEntities(Set<E> entities); void retainEntityGroup(Set<G> entityGroups); void removeEntityGroup(Set<G> entityGroups); void clear(); long monitoringPeriodMs();  }### Answer:
@Test public void testPeekCurrentWindow() { MetricSampleAggregator<String, IntegerEntity> aggregator = new MetricSampleAggregator<>(NUM_WINDOWS, WINDOW_MS, MIN_SAMPLES_PER_WINDOW, 0, _metricDef); populateSampleAggregator(2, 1, aggregator, ENTITY1); populateSampleAggregator(2, MIN_SAMPLES_PER_WINDOW, aggregator, ENTITY2); CruiseControlUnitTestUtils.populateSampleAggregator(1, MIN_SAMPLES_PER_WINDOW, aggregator, ENTITY3, 0, WINDOW_MS, _metricDef); Map<IntegerEntity, ValuesAndExtrapolations> currentWindowMetrics = aggregator.peekCurrentWindow(); assertEquals(FORCED_INSUFFICIENT, currentWindowMetrics.get(ENTITY1).extrapolations().get(0)); assertTrue(currentWindowMetrics.get(ENTITY2).extrapolations().isEmpty()); assertEquals(NO_VALID_EXTRAPOLATION, currentWindowMetrics.get(ENTITY3).extrapolations().get(0)); }