Move deletion of session related data to DAO method

src/main/java/de/thm/arsnova/dao/CouchDBDao.java

@@ -1676,6 +1676,7 @@ public class CouchDBDao implements IDatabaseDao, ApplicationEventPublisherAware
 	@Caching(evict = { @CacheEvict("sessions"), @CacheEvict(cacheNames="sessions", key="#p0.keyword") })
 	public void deleteSession(final Session session) {
 		try {
+			deleteAllQuestionsWithAnswers(session);
 			deleteDocument(session.get_id());
 			LOGGER.debug("Deleted session document {} and related data.", session.get_id());
 		} catch (final IOException e) {
@@ -1693,7 +1694,6 @@ public class CouchDBDao implements IDatabaseDao, ApplicationEventPublisherAware
 			Session s = new Session();
 			s.set_id(oldDoc.getId());
 			s.set_rev(oldDoc.getJSONObject("value").getString("_rev"));
-			deleteAllQuestionsWithAnswers(s);
 			deleteSession(s);
 		}
 

src/main/java/de/thm/arsnova/dao/IDatabaseDao.java

@@ -144,6 +144,11 @@ public interface IDatabaseDao {
 
 	Session changeSessionCreator(Session session, String newCreator);
 
+	/**
+	 * Deletes a session and related data.
+	 *
+	 * @param session the session for deletion
+	 */
 	void deleteSession(Session session);
 
 	boolean deleteInactiveGuestSessions(long lastActivityBefore);

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

@@ -405,7 +405,6 @@ public class SessionService implements ISessionService, ApplicationEventPublishe
 			prepSubjects.add("");
 		}
 
-		databaseDao.deleteAllQuestionsWithAnswers(session);
 		databaseDao.deleteSession(session);
 
 		this.publisher.publishEvent(new DeleteSessionEvent(this, session));

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

@@ -173,7 +173,6 @@ public class SessionServiceTest {
 
 			sessionService.deleteSession(session.getKeyword());
 
-			verify(mockDatabase).deleteAllQuestionsWithAnswers(session);
 			verify(mockDatabase).deleteSession(session);
 		} finally {
 			ReflectionTestUtils.setField(getTargetObject(sessionService), "databaseDao", tempDatabase);