### Question:
UniqueColumnCombinationRanking extends Ranking { protected void calculateOccurrenceRatio(UniqueColumnCombinationResult result) { Set<ColumnIdentifier> columns = result.getColumnCombination().getColumnIdentifiers(); String tableName = result.getTableName(); result.setOccurrenceRatio(calculateOccurrenceRatio(columns, tableName)); } UniqueColumnCombinationRanking(List<UniqueColumnCombinationResult> results,
                                        Map<String, TableInformation> tableInformationMap); @Override void calculateDataIndependentRankings(); @Override void calculateDataDependentRankings();  }### Answer:
@Test public void testCalculateOccurrenceRatio() throws Exception { UniqueColumnCombinationRanking ranking = new UniqueColumnCombinationRanking( uniqueColumnCombinationResults, tableInformationMap); UniqueColumnCombinationResult result = uniqueColumnCombinationResults.get(1); ranking.calculateOccurrenceRatio(result); assertEquals(1.0, result.getOccurrenceRatio(), 0.0); }