Method mute of CDPlayer tested on checkingTheEffectAfterRun -> VariableMutedShouldBeTrue.

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

@@ -25,6 +25,8 @@ public class CDPlayer implements Device {
 
     private List<String>favoriteSongs=new ArrayList<>();
 
+    private boolean muted=false;
+
     @Override
     public void louder() {
         if(volume < 100) {
@@ -109,6 +111,7 @@ public class CDPlayer implements Device {
 
     @Override
     public String mute() {
+        muted=true;
         return ("Volume muted.");
     }
 
@@ -229,4 +232,8 @@ public class CDPlayer implements Device {
     public List<String> getFavoriteSongs() {
         return favoriteSongs;
     }
+
+    public boolean isMuted() {
+        return muted;
+    }
 }

src/test/java/device/cdPlayer/CDPlayerTest.java

@@ -534,12 +534,19 @@ class CDPlayerTest {
     @ParameterizedTest
     @MethodSource("muteTestData")
     void muteTest(String testName,String cases, CDPlayer _cdPlayer,String expectedResult) {
-        assertThat(_cdPlayer.mute()).describedAs(testName).isEqualTo(expectedResult);
+        if(cases.equals("Case1")) {
+            assertThat(_cdPlayer.mute()).describedAs(testName).isEqualTo(expectedResult);
+        }
+        if(cases.equals("Case2")) {
+            _cdPlayer.mute();
+            assertThat(_cdPlayer.isMuted()).describedAs(testName).isEqualTo(true);
+        }
     }
     static Stream<Arguments> muteTestData () {
         CDPlayer cdPlayer1 = new CDPlayer();
         return Stream.of(
-                Arguments.of("[mute() by checkingTheReturnValue ] => ShouldReturnAString", "Case1", cdPlayer1, "Volume muted.")
+                Arguments.of("[mute() by checkingTheReturnValue ] => ShouldReturnAString", "Case1", cdPlayer1, "Volume muted."),
+                Arguments.of("[mute() by checkingTheEffectAfterRun ] => VariableMutedShouldBeTrue", "Case2", cdPlayer1, "Volume muted.")
         );
     }