Initialize DataStore with TestScope.backgroundScope in unit tests

[SimonMarquis]

Another solution could be to enforce a TestScope parameter in the TestDataStoreModule, let me know if you prefer this solution (but then, @ApplicationScope could not be re-used).

nowinandroid/core/datastore-test/src/main/kotlin/com/google/samples/apps/nowinandroid/core/datastore/test/TestDataStoreModule.kt

Lines 38 to 61 in c4ebde1

	internal object TestDataStoreModule {
	@Provides
	@Singleton
	fun providesUserPreferencesDataStore(
	@ApplicationScope scope: CoroutineScope,
	userPreferencesSerializer: UserPreferencesSerializer,
	tmpFolder: TemporaryFolder,
	): DataStore<UserPreferences> =
	tmpFolder.testUserPreferencesDataStore(
	coroutineScope = scope,
	userPreferencesSerializer = userPreferencesSerializer,
	)
	}
	fun TemporaryFolder.testUserPreferencesDataStore(
	coroutineScope: CoroutineScope,
	userPreferencesSerializer: UserPreferencesSerializer = UserPreferencesSerializer(),
	) = DataStoreFactory.create(
	serializer = userPreferencesSerializer,
	scope = coroutineScope,
	) {
	newFile("user_preferences_test.pb")
	}

Fixes #1647