Productive code for case:1 of method-test next created.

src/main/java/device/cdPlayer/CDPlayer.java

@@ -42,7 +42,10 @@ public class CDPlayer implements Device {
 
     @Override
     public void next() {
+        List<String> playList =  Arrays.asList(loadedCD.getPlayList());
+        int indexOfActualPlayTrack=playList.indexOf(actualPlayTrack);
 
+        this.actualPlayTrack=playList.get(indexOfActualPlayTrack +1);
     }
 
     @Override
@@ -115,7 +118,8 @@ public class CDPlayer implements Device {
     }
 
     public String getSongByNumber(int songNr){
-        return "";
+        List<String> playList =  Arrays.asList(loadedCD.getPlayList());
+        return playList.get(songNr);
     }
 
     public String getActualPlayTrack() {