@Override @Test default void Bag_occurrencesOf() { SortedBag<Integer> bag = this.newWith(3, 3, 3, 2, 2, 1); assertEquals(0, bag.occurrencesOf(0)); assertEquals(1, bag.occurrencesOf(1)); assertEquals(2, bag.occurrencesOf(2)); assertEquals(3, bag.occurrencesOf(3)); }