@Test
public void testTotalArea() {
// Given
List<Shapes> contents = Arrays.asList(new Circle(5), new Rectangle(3, 6), new Triangle(7, 2));
ToyBox toyBox = new ToyBox(contents);
// When
double totalArea = toyBox.calculateTotalArea();
double expectedTotalArea = (25 * Math.PI) + 18 + 7;
// Then
assertThat(totalArea, is(expectedTotalArea));
}