Update OfflineFirstNewsRepositoryTest.kt

Improve the unit test to perform meaningful comparisons instead of merely comparing two empty lists.

core/data/src/test/kotlin/com/google/samples/apps/nowinandroid/core/data/repository/OfflineFirstNewsRepositoryTest.kt

@@ -89,6 +89,10 @@ class OfflineFirstNewsRepositoryTest {
     @Test
     fun offlineFirstNewsRepository_news_resources_stream_is_backed_by_news_resource_dao() =
         testScope.runTest {
+            // After sync, newsResourceDao.getNewsResources().first() and 
+            // subject.getNewsResources().first() will return non-empty lists. 
+            subject.syncWith(synchronizer)
+            
             assertEquals(
                 newsResourceDao.getNewsResources()
                     .first()