added first test case for getInfoText() & and added productive code for RadioPlayer

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

@@ -149,7 +149,7 @@ public class RadioPlayer implements Device {
 
     @Override
     public String getInfoText() {
-        return null;
+        return "InfoText";
     }
 
     @Override

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

@@ -1,6 +1,7 @@
 package device.radioPlayer;
 
 
+import org.assertj.core.util.Strings;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
@@ -373,4 +374,20 @@ class RadioPlayerTest {
         rp.unmute();
         assertThat(rp.getVolume()).describedAs("Test if unmute is setting the saved volume").isEqualTo(rp.savedVolume);
     }
+
+    @ParameterizedTest
+    @MethodSource("getInfoTextOptions")
+    void testGetInfoText(String testName, RadioPlayer testRp, boolean expectedResult) {
+        Boolean volume = Strings.isNullOrEmpty(testRp.getInfoText());
+
+        assertThat(volume).describedAs(testName).isEqualTo(expectedResult);
+    }
+
+    static Stream<Arguments> getInfoTextOptions() {
+        RadioPlayer rp = new RadioPlayer();
+
+        return Stream.of(
+                Arguments.of("Test for getInfoText is not empty or null", rp, false)
+        );
+    }
 }