@Test
 public void clearsAVector() {
   fillVector();
   assertEquals(vector.capacity(), vector.size());
   vector.clear();
   assertEquals(0, vector.size());
 }
 @Test
 public void checksExpandedVectorCapacity() {
   fillVector();
   vector.add(new Circle(2.0));
   assertTrue(vector.capacity() > SortedShapeVector.capacityIncrement);
 }
 @Test
 public void checksNewVectorCapacity() {
   assertEquals(SortedShapeVector.capacityIncrement, vector.capacity());
 }
 private void fillVector() {
   for (double r = 0.0; r < vector.capacity(); r += 1.0) {
     vector.add(new Circle(r + 1.0));
   }
 }