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