UsbPlayerTest.louder_10_Test Forth Case

src/main/java/device/usbPlayer/UsbPlayer.java

@@ -126,10 +126,13 @@ public class UsbPlayer implements Device {
     }
 
     public void Louder_10() {
-        Lautstaerke += 10;
-        if (Lautstaerke > 100) {
-            Lautstaerke = 100;
+        if(this.soundWas == -1) {
+            Lautstaerke += 10;
+            if (Lautstaerke > 100) {
+                Lautstaerke = 100;
+            }
         }
+
     }
 
     public void quieter_10() {

src/test/java/device/usbPlayer/UsbPlayerTest.java

@@ -185,22 +185,29 @@ class UsbPlayerTest {
 
     static Stream<Arguments> louder_10_Options() {
         USB_Stick USBDrive = new USB_Stick();
+        //first case
         UsbPlayer up1 = new UsbPlayer(USBDrive);
         up1.Louder_10();
-
+        //Second case
         UsbPlayer up2 = new UsbPlayer(USBDrive);
-        for (int i = 0; i <= 3; i++) {
+        for (int i = 0; i < 3; i++) {
             up2.Louder_10();
         }
-        up2.quieter_10();
-
+        //third case
         UsbPlayer up3 = new UsbPlayer(USBDrive);
         up3.setLautstaerke(100);
         up3.Louder_10();
+        //forth case
+        UsbPlayer up4 = new UsbPlayer(USBDrive);
+        up4.setLautstaerke(10);
+        up4.mute();
+        up4.Louder_10();
+
         return Stream.of(
                 Arguments.of("Volume was 0, should be 10 ", up1, 10),
                 Arguments.of("Volume was 0, should be 30 ", up2, 30),
-                Arguments.of("Volume was 100, should stay 100 ", up3, 100)
+                Arguments.of("Volume was 100, should stay 100 ", up3, 100),
+                Arguments.of("Volume is muted,no change can be made ", up4, 0)
         );
     }