Throw NotFoundException if there are no feedbacks to get average value.

src/main/java/de/thm/arsnova/controller/FeedbackController.java

@@ -29,7 +29,6 @@ import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
-import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.ResponseBody;
 
 import de.thm.arsnova.entities.Feedback;

src/main/java/de/thm/arsnova/services/FeedbackService.java

@@ -31,6 +31,7 @@ import org.springframework.stereotype.Service;
 import de.thm.arsnova.dao.IDatabaseDao;
 import de.thm.arsnova.entities.Feedback;
 import de.thm.arsnova.entities.User;
+import de.thm.arsnova.exceptions.NotFoundException;
 import de.thm.arsnova.socket.ARSnovaSocketIOServer;
 
 @Service
@@ -81,11 +82,11 @@ public class FeedbackService implements IFeedbackService {
 		double sum = values.get(1) + (values.get(2) * 2) + (values.get(3) * 3);
 
 		if (count == 0)
-			return 0;
+			throw new NotFoundException();
 
 		return sum / count;
 	}
-	
+
 	@Override
 	public long getAverageFeedbackRounded(String sessionkey) {
 		return Math.round(this.getAverageFeedback(sessionkey));

src/test/java/de/thm/arsnova/services/FeedbackServiceTest.java

@@ -78,9 +78,15 @@ public class FeedbackServiceTest {
 	}
 
 	@Test
+	public void testShouldReturnZeroFeedbackCountForNoFeedbackAtAll() {
+		userService.setUserAuthenticated(true);
+		assertEquals(0, feedbackService.getFeedbackCount("12345678"));
+	}
+	
+	@Test(expected = NotFoundException.class)
 	public void testShouldReturnAverageFeedbackForNoFeedbackAtAll() {
 		userService.setUserAuthenticated(true);
-		assertEquals(0, feedbackService.getAverageFeedback("12345678"), 0);
+		feedbackService.getAverageFeedback("12345678");
 	}
 	
 	@Test