[Test] Tested files service and made it more stable

Author: md-weber

lib/domain/files_service.dart

@@ -2,11 +2,13 @@ import 'package:flashcard_project/domain/model/file_information.dart';
 import 'package:flashcard_project/repository/gdrive_repo.dart';
 import 'package:googleapis/drive/v2.dart';
 
-class FileService {
-  final GDriveRepo _sheetRepo = GDriveRepo();
+class FilesService {
+  final GDriveRepo _gDriveRepo;
+
+  FilesService(this._gDriveRepo);
 
   Future<List<LectureFolder>> getPossibleLectures() async {
-    List<File> filesAndFolders = await _sheetRepo.getFilesAndFolders();
+    List<File> filesAndFolders = await _gDriveRepo.getFilesAndFolders();
 
     final spreadsheets = filesAndFolders
         .where((element) => element.mimeType?.contains("spreadsheet") ?? false)

lib/ui/screen/lesson_selector_screen.dart

@@ -1,5 +1,6 @@
 import 'package:flashcard_project/domain/files_service.dart';
 import 'package:flashcard_project/domain/model/file_information.dart';
+import 'package:flashcard_project/repository/gdrive_repo.dart';
 import 'package:flashcard_project/ui/screen/home_page.dart';
 import 'package:flutter/material.dart';
 
@@ -11,7 +12,7 @@ class LessonSelectorScreen extends StatefulWidget {
 }
 
 class _LessonSelectorScreenState extends State<LessonSelectorScreen> {
-  FileService fileService = FileService();
+  FilesService fileService = FilesService(GDriveRepo());
   late Future<List<LectureFolder>> getPossibleLectures;
 
   @override

test/domain/files_service_test.dart

@@ -0,0 +1,42 @@
+import 'package:flashcard_project/domain/files_service.dart';
+import 'package:flashcard_project/repository/gdrive_repo.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:googleapis/drive/v2.dart';
+import 'package:mockito/annotations.dart';
+import 'package:mockito/mockito.dart';
+
+import 'files_service_test.mocks.dart';
+
+@GenerateMocks([GDriveRepo])
+void main() {
+  group("FilesService", () {
+    final mockGDriveRepo = MockGDriveRepo();
+    final subject = FilesService(mockGDriveRepo);
+
+    test(
+        "WHEN the GDrive returns an empty list THEN the service return also an empty",
+        () async {
+      when(mockGDriveRepo.getFilesAndFolders()).thenAnswer(
+        (realInvocation) async => [],
+      );
+
+      expect(await subject.getPossibleLectures(), []);
+    });
+
+    test(
+        " WHEN the GDrive returns an folder with one spreadsheet THEN service returns it",
+        () async {
+      when(mockGDriveRepo.getFilesAndFolders()).thenAnswer(
+        (realInvocation) async => [
+          File(mimeType: "folder", title: "Learning English"),
+          File(mimeType: "spreadsheet", title: "Lesson 1")
+        ],
+      );
+
+      var result = await subject.getPossibleLectures();
+      expect(result[0].name, "Learning English");
+      expect(result[0].spreadsheets.length, 1);
+      expect(result[0].spreadsheets[0].name, "Lesson 1");
+    });
+  });
+}