added second test case for mute() & and added productive code for RadioPlayer

src/main/java/device/radioPlayer/RadioPlayer.java

@@ -22,6 +22,7 @@ public class RadioPlayer implements Device {
     LocalDateTime now = LocalDateTime.now();
     int hour = now.getHour();
     int Lautstaerke = 0;
+    int savedVolume;
     String playedStation = "";
 
     public String getYouFMInfoByTime(int x) {
@@ -193,6 +194,7 @@ public class RadioPlayer implements Device {
 
     @Override
     public String mute() {
+        savedVolume = getVolume();
         setLautstaerke(0);
         return "RadioPlayer is muted now";
     }

src/test/java/device/radioPlayer/RadioPlayerTest.java

@@ -345,9 +345,10 @@ class RadioPlayerTest {
 
     @ParameterizedTest
     @MethodSource("muteOptions")
-    void testMute(String testName, RadioPlayer testRp, int expectedResult) {
-
-        int volume = testRp.getVolume();
+    void testMute(String testName, String testTyp, RadioPlayer testRp, int expectedResult) {
+        int volume;
+        if (testTyp.equals("actual")) volume = testRp.getVolume();
+        else volume = testRp.savedVolume;
         assertThat(volume).describedAs(testName).isEqualTo(expectedResult);
     }
 
@@ -355,9 +356,13 @@ class RadioPlayerTest {
         RadioPlayer rp = new RadioPlayer();
         rp.setLautstaerke(25);
         rp.mute();
+        RadioPlayer rp1 = new RadioPlayer();
+        rp1.setLautstaerke(30);
+        rp1.mute();
 
         return Stream.of(
-                Arguments.of("Test for mute RadioPlayer if volume is actually 0", rp, 0)
+                Arguments.of("Test for mute RadioPlayer if volume is actually 0", "actual", rp, 0),
+                Arguments.of("Test for mute RadioPlayer if volume is saved before muting", "saved", rp1, 30)
         );
     }
 }