@Test
public void test_GetYouTubeId_ReturnsNull_WhenVideoIsNotAYouTubeVideo() {
video = new Video("http://vimeo.com/123456789");
assertNull(video.getYouTubeId());
}
@Test
public void test_GetYouTubeId_ReturnsTheYouTubeId_WhenVideoIsAYouTubeVideo() {
video = new Video("http://youtube.com/watch?v=DUAWAfHnx9Y");
assertEquals("DUAWAfHnx9Y", video.getYouTubeId());
}