RadioPlayer added quieter function + AssertJ test for quieter

src/main/java/device/CDPlayer.java

@@ -5,7 +5,7 @@ public class CDPlayer implements Device {
     public void louder() {
 
     }
-/*
+
     @Override
     public void quieter() {
 
@@ -46,5 +46,4 @@ public class CDPlayer implements Device {
         return null;
     }
 
- */
 }

src/main/java/device/Device.java

@@ -3,10 +3,7 @@ package device;
 public interface Device {
 
 	void louder();
-	/*
 	void quieter();
-
-	void quiter();
 	int getVolume();
 	void next();
 	void prev();
@@ -15,5 +12,5 @@ public interface Device {
 	void chooseOption(String opt);
 	String play();
 
-	 */
+
 	}

src/main/java/device/RadioPlayer.java

@@ -19,12 +19,15 @@ public class RadioPlayer implements Device {
             Lautstaerke = 100;
         }
     }
-    /*
+
     @Override
     public void quieter() {
-
+        if(Lautstaerke > 0) {
+			Lautstaerke -= 1;
+		} else {
+			Lautstaerke = 0;
+		}
     }
-
     @Override
     public int getVolume() {
         return 0;
@@ -59,6 +62,4 @@ public class RadioPlayer implements Device {
     public String play() {
         return null;
     }
-
-     */
 }

src/main/java/device/UsbPlayer.java

@@ -6,7 +6,7 @@ public class UsbPlayer implements Device{
     public void louder() {
 
     }
-/*
+
     @Override
     public void quieter() {
 
@@ -47,5 +47,4 @@ public class UsbPlayer implements Device{
         return null;
     }
 
- */
 }

src/test/java/device/CDPlayerTest.java

@@ -5,7 +5,7 @@ import org.junit.jupiter.api.Test;
 import static org.junit.jupiter.api.Assertions.*;
 
 class CDPlayerTest {
-
+/*
     @Test
     void louder() {
     }
@@ -41,4 +41,6 @@ class CDPlayerTest {
     @Test
     void play() {
     }
+
+ */
 }

src/test/java/device/RadioPlayerTest.java

@@ -22,11 +22,15 @@ class RadioPlayerTest {
         rp.louder();
         assertThat(rp.getLautstaerke()).isEqualTo(100);
     }
-/*
+
     @Test
     void quieter() {
+        rp.setLautstaerke(1);
+        rp.quieter();
+        assertThat(rp.getLautstaerke()).isEqualTo(0);
     }
 
+/*
     @Test
     void getVolume() {
     }

src/test/java/device/UsbPlayerTest.java

@@ -6,6 +6,7 @@ import static org.junit.jupiter.api.Assertions.*;
 
 class UsbPlayerTest {
 
+/*
     @Test
     void louder() {
     }
@@ -41,4 +42,5 @@ class UsbPlayerTest {
     @Test
     void play() {
     }
+ */
 }