### Question:
VariantAggregatedStatsCalculator { public static Set<String> getCohorts(Properties tagMap) { Set<String> cohorts = null; if (tagMap != null) { cohorts = new LinkedHashSet<>(); for (String key : tagMap.stringPropertyNames()) { int index = key.indexOf("."); if (index >= 0) { cohorts.add(key.substring(0, index)); } } } return cohorts; } VariantAggregatedStatsCalculator();  VariantAggregatedStatsCalculator(Properties tagMap); void calculate(List<Variant> variants); void calculate(Variant variant); void calculate(Variant variant, StudyEntry study); static void addGenotypeWithGTS(Map<String, String> fileData, String[] splitsGTC,
                                          String reference, String[] alternateAlleles, int numAllele, VariantStats cohortStats); static Set<String> getCohorts(Properties tagMap); static void getGenotype(int index, Integer alleles[]);  }### Answer:
@Test public void getCohorts() { Properties properties = new Properties(); properties.put("EUR.GTC", "EUR_HPG_GTC"); properties.put("EUR.AC", "EUR_AC"); properties.put("EUR.AN", "EUR_AN"); properties.put("EUR.AF", "EUR_AF"); properties.put("ALL.AN", "AN"); properties.put("ALL.AF", "AF"); properties.put(VariantAggregatedEVSStatsCalculator.GROUPS_ORDER, "EUR,ALL"); assertEquals(new LinkedHashSet<>(Arrays.asList("EUR", "ALL")), VariantAggregatedStatsCalculator.getCohorts(properties)); }