### Question:
LongList { public void add(long l) { ensureCapacity(size + 1); longs[size++] = l; } LongList();  LongList(int initialCapacity); static LongList of(long... values); void add(long l); void addAll(LongList other); int getSize(); long get(int i); boolean contains(long l); boolean remove(long l); long remove(int i); void clear(); @Override String toString(); long[] toArray(); boolean isEmpty();  }### Answer:
@Test void testAdd() { assertThat(longList.isEmpty()).isTrue(); longList.add(42); assertThat(longList.isEmpty()).isFalse(); assertThat(longList.getSize()).isEqualTo(1); assertThat(longList.get(0)).isEqualTo(42); }