@Test
 public final void testSetArtist() {
   testGetArtist();
   siExtended.setArtist("Steven");
   assertEquals("Steven", siExtended.getArtist());
 }
 @Test
 public final void testSongInfo() {
   assertEquals(null, siBasic.getArtist());
   assertEquals(null, siBasic.getTitle());
 }
 @Test
 public final void testGetArtist() {
   assertEquals("Hendrik", siExtended.getArtist());
 }
 @Test
 public final void testSongInfoStringString() {
   assertEquals("Hendrik", siExtended.getArtist());
   assertEquals("I only sing in the shower", siExtended.getTitle());
 }