public class CompositeHelloWorldTest {
@Test
public void testCompositeHelloWorld(){
HelloWorld emptyCompositeHelloWorld = new CompositeHelloWorld();
assertThat(emptyCompositeHelloWorld.helloWorld(),isEmptyString());
HelloWorld compositeHelloWorld = new CompositeHelloWorld(new CompositeHelloWorld.DefaultHelloWorld());
assertThat(compositeHelloWorld.helloWorld(),is("Hello Composite!"));
}
}