### Question:
ObjectStack { public boolean isEmpty() { return collection.isEmpty(); } ObjectStack(); boolean isEmpty(); int size(); void push(Object value); Object pop(); Object peek(); void clear();  }### Answer:
@Test void testIsEmptyWithEmptyStack() { assertTrue(createStackWithNElements(0).isEmpty()); }
@Test void testIsEmptyWithNonEmptyStack() { assertFalse(createStackWithNElements(5).isEmpty()); }