### Question:
ObjectStack { public int size() { return collection.size(); } ObjectStack(); boolean isEmpty(); int size(); void push(Object value); Object pop(); Object peek(); void clear();  }### Answer:
@Test void testSizeWithEmptyStack() { assertEquals(0, createStackWithNElements(0).size()); }
@Test void testSizeWithNonEmptyStack() { assertEquals(5, createStackWithNElements(5).size()); }