System.out.println("swap");
List<TestLabelable> items = new ArrayList<TestLabelable>(originalItems);
CrossValidationPrep instance = new CrossValidationPrep();
instance.swap(items, 0, items.size() - 1);
assertEquals("size unchanged", originalItems.size(), items.size());
assertEquals("first moved to last", originalItems.get(0), items.get(items.size() - 1));
assertEquals("last moved to first", originalItems.get(originalItems.size() - 1), items.get(0));
}