Initialize DataStore with `TestScope.backgroundScope` in unit tests

Fixes #1647

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

@@ -73,7 +73,7 @@ class OfflineFirstNewsRepositoryTest {
     @Before
     fun setup() {
         niaPreferencesDataSource = NiaPreferencesDataSource(
-            tmpFolder.testUserPreferencesDataStore(testScope),
+            tmpFolder.testUserPreferencesDataStore(testScope.backgroundScope),
         )
         newsResourceDao = TestNewsResourceDao()
         topicDao = TestTopicDao()

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

@@ -60,7 +60,7 @@ class OfflineFirstTopicsRepositoryTest {
         topicDao = TestTopicDao()
         network = TestNiaNetworkDataSource()
         niaPreferences = NiaPreferencesDataSource(
-            tmpFolder.testUserPreferencesDataStore(testScope),
+            tmpFolder.testUserPreferencesDataStore(testScope.backgroundScope),
         )
         synchronizer = TestSynchronizer(niaPreferences)
 

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

@@ -51,7 +51,7 @@ class OfflineFirstUserDataRepositoryTest {
     @Before
     fun setup() {
         niaPreferencesDataSource = NiaPreferencesDataSource(
-            tmpFolder.testUserPreferencesDataStore(testScope),
+            tmpFolder.testUserPreferencesDataStore(testScope.backgroundScope),
         )
 
         subject = OfflineFirstUserDataRepository(

core/datastore/src/test/kotlin/com/google/samples/apps/nowinandroid/core/datastore/NiaPreferencesDataSourceTest.kt

@@ -40,7 +40,7 @@ class NiaPreferencesDataSourceTest {
     @Before
     fun setup() {
         subject = NiaPreferencesDataSource(
-            tmpFolder.testUserPreferencesDataStore(testScope),
+            tmpFolder.testUserPreferencesDataStore(testScope.backgroundScope),
         )
     }