Add tests

test/cart_test.dart

@@ -0,0 +1,14 @@
+// ignore_for_file: invalid_use_of_protected_member
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:thesis_shop/stores/cart_store.dart';
+
+import 'product_service_mock.dart';
+
+void main() {
+  test('test cart store', () {
+    final cartStore = CartStore();
+    cartStore.increaseAmountOfProduct(demoProducts.first);
+    expect(cartStore.state[demoProducts.first.title], 1);
+  });
+}

test/product_service_mock.dart

@@ -1,15 +1,17 @@
 import 'package:thesis_shop/models/product.dart';
 import 'package:thesis_shop/service/product_service.dart';
 
+const demoProducts = [
+  Product(title: 'Bananen', price: 3),
+  Product(title: 'Äpfel', price: 2),
+  Product(title: 'Birnen', price: 2.5),
+  Product(title: 'Kirschen', price: 1.2),
+];
+
 class MockedProductService implements ProductService {
   @override
   Future<List<Product>> fetchProducts() async {
-    return const [
-      Product(title: 'Bananen', price: 3),
-      Product(title: 'Äpfel', price: 2),
-      Product(title: 'Birnen', price: 2.5),
-      Product(title: 'Kirschen', price: 1.2),
-    ];
+    return demoProducts;
   }
 
   @override

test/total_price_test.dart

@@ -0,0 +1,21 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:thesis_shop/screens/cart/total_price_text.dart';
+import 'package:thesis_shop/stores/cart_store.dart';
+
+void main() {
+  testWidgets('test total price widget', (tester) async {
+    await tester.pumpWidget(
+      MaterialApp(
+        home: ProviderScope(
+          overrides: [
+            totalPriceProvider.overrideWithValue(10.0),
+          ],
+          child: const TotalPriceText(),
+        ),
+      ),
+    );
+    expect(find.text('Gesamtpreis: 10.00€'), findsOneWidget);
+  });
+}