### Question:
MmdTool extends BasicTool { static List<Item> extractVariableList(List<String> targetNames, ColumnRegistry columnRegistry) { final List<Item> variableList = new ArrayList<>(); for (String targetName : targetNames) { variableList.add(columnRegistry.getColumn(targetName)); } return variableList; } MmdTool(); static void main(String[] args); @Override void initialize();  }### Answer:
@Test public void testExtractVariableList() { final ColumnRegistry columnRegistry = new ColumnRegistry(); columnRegistry.register(new ColumnBuilder().name("Heike").dimensions("a b c").rank(3).build()); columnRegistry.register(new ColumnBuilder().name("Klaus").dimensions("left right").rank(2).build()); columnRegistry.register(new ColumnBuilder().name("Carmen").dimensions("up down").rank(2).build()); final List<String> targetNames = new ArrayList<>(); targetNames.add("Heike"); targetNames.add("Carmen"); final List<Item> variableList = MmdTool.extractVariableList(targetNames, columnRegistry); assertNotNull(variableList); assertEquals(2, variableList.size()); assertEquals("Heike", variableList.get(0).getName()); assertEquals("Carmen", variableList.get(1).getName()); }