PullRequest for RadioPlayer function prev

src/main/java/device/RadioPlayer.java

@@ -56,7 +56,10 @@ public class RadioPlayer implements Device {
 
     @Override
     public void prev() {
-
+        int currentIndex=Playlist.indexOf(playTrack);
+        int nextIndex=Playlist.size()-1;
+        if(currentIndex!=0){nextIndex=(currentIndex-1);}
+        playTrack=Playlist.get(nextIndex);
     }
 
     @Override

src/test/java/device/RadioPlayerTest.java

@@ -47,12 +47,16 @@ class RadioPlayerTest {
         int currentIndex=rp.Playlist.indexOf(rp.playTrack);
         assertThat(rp.playTrack).isEqualTo(rp.Playlist.get((currentIndex)%rp.Playlist.size()));
     }
-/*
+
 
     @Test
     void prev() {
-    }
+        rp.prev();
+        int currentIndex=rp.Playlist.indexOf(rp.playTrack);
+        assertThat(rp.playTrack).isEqualTo(rp.Playlist.get((currentIndex)%rp.Playlist.size()));
 
+    }
+/*
     @Test
     void getInfoText() {
     }