### Question:
StringStack implements Iterable<String> { public boolean isEmpty() { return size() == 0; } StringStack(String... xs);  StringStack(Iterable<String> xs); int size(); boolean isEmpty(); boolean contains(String o); boolean add(String e); void clear(); String get(int index); int indexOf(String o); Iterator<String> iterator();  }### Answer:
@Test public void testIsEmpty() { assertTrue(new StringStack().isEmpty()); assertFalse(new StringStack("moo").isEmpty()); }