### Question:
BasicStatisticRanking extends Ranking { protected void calculateOccurrenceRatio(BasicStatisticResult result) { Set<ColumnIdentifier> columns = result.getColumnCombination().getColumnIdentifiers(); String tableName = result.getTableName(); result.setOccurrenceRatio(calculateOccurrenceRatio(columns, tableName)); } BasicStatisticRanking(List<BasicStatisticResult> results,
                               Map<String, TableInformation> tableInformationMap); @Override void calculateDataIndependentRankings(); @Override void calculateDataDependentRankings();  }### Answer:
@Test public void testCalculateOccurrenceRatio() throws Exception { BasicStatisticRanking ranking = new BasicStatisticRanking(basicStatisticResults, tableInformationMap); BasicStatisticResult result = basicStatisticResults.get(0); ranking.calculateOccurrenceRatio(result); assertEquals(0.5, result.getOccurrenceRatio(), 0.0); }