Add remaining tests for shopping cart feature

# Conflicts:
#	ecommerce_app/test/src/goldens/products_list_1000x1000.png
#	ecommerce_app/test/src/goldens/products_list_300x600.png
#	ecommerce_app/test/src/goldens/products_list_600x800.png

ecommerce_app/integration_test/purchase_flow_test.dart

@@ -0,0 +1,35 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:integration_test/integration_test.dart';
+
+import '../test/src/robot.dart';
+
+void main() {
+  IntegrationTestWidgetsFlutterBinding.ensureInitialized();
+  testWidgets('Full purchase flow', (tester) async {
+    final r = Robot(tester);
+    await r.pumpMyApp();
+    r.products.expectFindAllProductCards();
+    // add to cart flows
+    await r.products.selectProduct();
+    await r.products.setProductQuantity(3);
+    await r.cart.addToCart();
+    await r.cart.openCart();
+    r.cart.expectFindNCartItems(1);
+    await r.closePage();
+    // sign in
+    await r.openPopupMenu();
+    await r.auth.openEmailPasswordSignInScreen();
+    await r.auth.signInWithEmailAndPassword();
+    r.products.expectFindAllProductCards();
+    // check cart again (to verify cart synchronization)
+    await r.cart.openCart();
+    r.cart.expectFindNCartItems(1);
+    await r.closePage();
+    // sign out
+    await r.openPopupMenu();
+    await r.auth.openAccountScreen();
+    await r.auth.tapLogoutButton();
+    await r.auth.tapDialogLogoutButton();
+    r.products.expectFindAllProductCards();
+  });
+}

ecommerce_app/test/src/features/authentication/auth_flow_test.dart

@@ -6,15 +6,15 @@ void main() {
   testWidgets('Sign in and sign out flow', (tester) async {
     final r = Robot(tester);
     await r.pumpMyApp();
-    r.expectFindAllProductCards();
+    r.products.expectFindAllProductCards();
     await r.openPopupMenu();
     await r.auth.openEmailPasswordSignInScreen();
     await r.auth.signInWithEmailAndPassword();
-    r.expectFindAllProductCards();
+    r.products.expectFindAllProductCards();
     await r.openPopupMenu();
     await r.auth.openAccountScreen();
     await r.auth.tapLogoutButton();
     await r.auth.tapDialogLogoutButton();
-    r.expectFindAllProductCards();
+    r.products.expectFindAllProductCards();
   });
 }

ecommerce_app/test/src/features/cart/cart_robot.dart

@@ -0,0 +1,93 @@
+import 'package:ecommerce_app/src/common_widgets/item_quantity_selector.dart';
+import 'package:ecommerce_app/src/features/cart/presentation/shopping_cart/shopping_cart_item.dart';
+import 'package:ecommerce_app/src/features/products/presentation/home_app_bar/shopping_cart_icon.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+class CartRobot {
+  CartRobot(this.tester);
+  final WidgetTester tester;
+
+  Future<void> addToCart() async {
+    final finder = find.text('Add to Cart');
+    expect(finder, findsOneWidget);
+    await tester.tap(finder);
+    await tester.pumpAndSettle();
+  }
+
+  // shopping cart
+  Future<void> openCart() async {
+    final finder = find.byKey(ShoppingCartIcon.shoppingCartIconKey);
+    expect(finder, findsOneWidget);
+    await tester.tap(finder);
+    await tester.pumpAndSettle();
+  }
+
+  void expectProductIsOutOfStock() async {
+    final finder = find.text('Out of Stock');
+    expect(finder, findsOneWidget);
+  }
+
+  Future<void> incrementCartItemQuantity(
+      {required int quantity, required int atIndex}) async {
+    final finder = find.byKey(ItemQuantitySelector.incrementKey(atIndex));
+    expect(finder, findsOneWidget);
+    for (var i = 0; i < quantity; i++) {
+      await tester.tap(finder);
+      await tester.pumpAndSettle();
+    }
+  }
+
+  Future<void> decrementCartItemQuantity(
+      {required int quantity, required int atIndex}) async {
+    final finder = find.byKey(ItemQuantitySelector.decrementKey(atIndex));
+    expect(finder, findsOneWidget);
+    for (var i = 0; i < quantity; i++) {
+      await tester.tap(finder);
+      await tester.pumpAndSettle();
+    }
+  }
+
+  Future<void> deleteCartItem({required int atIndex}) async {
+    final finder = find.byKey(ShoppingCartItemContents.deleteKey(atIndex));
+    expect(finder, findsOneWidget);
+    await tester.tap(finder);
+    await tester.pumpAndSettle();
+  }
+
+  void expectShoppingCartIsLoading() {
+    final finder = find.byType(CircularProgressIndicator);
+    expect(finder, findsOneWidget);
+  }
+
+  void expectShoppingCartIsEmpty() {
+    final finder = find.text('Your shopping cart is empty');
+    expect(finder, findsOneWidget);
+  }
+
+  void expectFindZeroCartItems() {
+    final finder = find.byType(ShoppingCartItem);
+    expect(finder, findsNothing);
+  }
+
+  void expectFindNCartItems(int count) {
+    final finder = find.byType(ShoppingCartItem);
+    expect(finder, findsNWidgets(count));
+  }
+
+  Text getItemQuantityWidget({int? atIndex}) {
+    final finder = find.byKey(ItemQuantitySelector.quantityKey(atIndex));
+    expect(finder, findsOneWidget);
+    return finder.evaluate().single.widget as Text;
+  }
+
+  void expectItemQuantity({required int quantity, int? atIndex}) {
+    final text = getItemQuantityWidget(atIndex: atIndex);
+    expect(text.data, '$quantity');
+  }
+
+  void expectShoppingCartTotalIs(String text) {
+    final finder = find.text(text);
+    expect(finder, findsOneWidget);
+  }
+}

ecommerce_app/test/src/features/cart/presentation/shopping_cart/shopping_cart_screen_controller_test.dart

@@ -0,0 +1,98 @@
+import 'package:ecommerce_app/src/features/cart/domain/item.dart';
+import 'package:ecommerce_app/src/features/cart/presentation/shopping_cart/shopping_cart_screen_controller.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:mocktail/mocktail.dart';
+
+import '../../../../mocks.dart';
+
+void main() {
+  const productId = '1';
+  group('updateItemQuantity', () {
+    test('update quantity, success', () async {
+      // setup
+      const item = Item(productId: productId, quantity: 3);
+      final cartService = MockCartService();
+      when(() => cartService.setItem(item)).thenAnswer(
+        (_) => Future.value(null),
+      );
+      final controller = ShoppingCartScreenController(cartService: cartService);
+      // run & verify
+      expectLater(
+        controller.stream,
+        emitsInOrder([
+          const AsyncLoading<void>(),
+          const AsyncData<void>(null),
+        ]),
+      );
+      await controller.updateItemQuantity(productId, 3);
+    });
+
+    test('update quantity, failure', () async {
+      // setup
+      const item = Item(productId: productId, quantity: 3);
+      final cartService = MockCartService();
+      when(() => cartService.setItem(item)).thenThrow(
+        (_) => Exception('Connection failed'),
+      );
+      final controller = ShoppingCartScreenController(cartService: cartService);
+      // run & verify
+      expectLater(
+        controller.stream,
+        emitsInOrder([
+          const AsyncLoading<void>(),
+          predicate<AsyncValue<void>>(
+            (value) {
+              expect(value.hasError, true);
+              return true;
+            },
+          ),
+        ]),
+      );
+      await controller.updateItemQuantity(productId, 3);
+      // verify
+      verify(() => cartService.setItem(item)).called(1);
+    });
+  });
+  group('removeItemById', () {
+    test('remove item, success', () async {
+      // setup
+      final cartService = MockCartService();
+      when(() => cartService.removeItemById(productId)).thenAnswer(
+        (_) => Future.value(null),
+      );
+      final controller = ShoppingCartScreenController(cartService: cartService);
+      // run & verify
+      expectLater(
+        controller.stream,
+        emitsInOrder([
+          const AsyncLoading<void>(),
+          const AsyncData<void>(null),
+        ]),
+      );
+      await controller.removeItemById(productId);
+    });
+    test('remove item, failure', () async {
+      // setup
+      final cartService = MockCartService();
+      when(() => cartService.removeItemById(productId)).thenThrow(
+        (_) => Exception('Connection failed'),
+      );
+      final controller = ShoppingCartScreenController(cartService: cartService);
+      // run & verify
+      expectLater(
+        controller.stream,
+        emitsInOrder([
+          const AsyncLoading<void>(),
+          predicate<AsyncValue<void>>(
+            (value) {
+              expect(value.hasError, true);
+              return true;
+            },
+          ),
+        ]),
+      );
+      await controller.removeItemById(productId);
+    });
+  });
+}

ecommerce_app/test/src/features/cart/presentation/shopping_cart/shopping_cart_screen_test.dart

@@ -0,0 +1,120 @@
+import 'package:flutter_test/flutter_test.dart';
+import '../../../../robot.dart';
+
+void main() {
+  group('shopping cart', () {
+    testWidgets('Empty shopping cart', (tester) async {
+      final r = Robot(tester);
+      await r.pumpMyApp();
+      r.products.expectFindNProductCards(14); // check all products are found
+      await r.cart.openCart();
+      r.cart.expectShoppingCartIsEmpty();
+    });
+
+    testWidgets('Add product with quantity = 1', (tester) async {
+      final r = Robot(tester);
+      await r.pumpMyApp();
+      await r.products.selectProduct();
+      await r.cart.addToCart();
+      await r.cart.openCart();
+      r.cart.expectItemQuantity(quantity: 1, atIndex: 0);
+      r.cart.expectShoppingCartTotalIs('Total: \$15.00');
+    });
+
+    testWidgets('Add product with quantity = 5', (tester) async {
+      final r = Robot(tester);
+      await r.pumpMyApp();
+      await r.products.selectProduct();
+      await r.products.setProductQuantity(5);
+      await r.cart.addToCart();
+      await r.cart.openCart();
+      r.cart.expectItemQuantity(quantity: 5, atIndex: 0);
+      r.cart.expectShoppingCartTotalIs('Total: \$75.00');
+    });
+
+    testWidgets('Add product with quantity = 6', (tester) async {
+      final r = Robot(tester);
+      await r.pumpMyApp();
+      await r.products.selectProduct();
+      await r.products.setProductQuantity(6);
+      await r.cart.addToCart();
+      await r.cart.openCart();
+      r.cart.expectItemQuantity(quantity: 5, atIndex: 0);
+      r.cart.expectShoppingCartTotalIs('Total: \$75.00');
+    });
+
+    testWidgets('Add product with quantity = 2, then increment by 2',
+        (tester) async {
+      final r = Robot(tester);
+      await r.pumpMyApp();
+      await r.products.selectProduct();
+      await r.products.setProductQuantity(2);
+      await r.cart.addToCart();
+      await r.cart.openCart();
+      await r.cart.incrementCartItemQuantity(quantity: 2, atIndex: 0);
+      r.cart.expectItemQuantity(quantity: 4, atIndex: 0);
+      r.cart.expectShoppingCartTotalIs('Total: \$60.00');
+    });
+
+    testWidgets('Add product with quantity = 5, then decrement by 2',
+        (tester) async {
+      final r = Robot(tester);
+      await r.pumpMyApp();
+      await r.products.selectProduct();
+      await r.products.setProductQuantity(5);
+      await r.cart.addToCart();
+      await r.cart.openCart();
+      await r.cart.decrementCartItemQuantity(quantity: 2, atIndex: 0);
+      r.cart.expectItemQuantity(quantity: 3, atIndex: 0);
+      r.cart.expectShoppingCartTotalIs('Total: \$45.00');
+    });
+
+    testWidgets('Add two products', (tester) async {
+      final r = Robot(tester);
+      await r.pumpMyApp();
+      // add first product
+      await r.products.selectProduct(atIndex: 0);
+      await r.cart.addToCart();
+      await r.goBack();
+      // add second product
+      await r.products.selectProduct(atIndex: 1);
+      await r.cart.addToCart();
+      await r.cart.openCart();
+      r.cart.expectFindNCartItems(2);
+      r.cart.expectShoppingCartTotalIs('Total: \$28.00');
+    });
+
+    testWidgets('Add product, then delete it', (tester) async {
+      final r = Robot(tester);
+      await r.pumpMyApp();
+      await r.products.selectProduct();
+      await r.cart.addToCart();
+      await r.cart.openCart();
+      await r.cart.deleteCartItem(atIndex: 0);
+      r.cart.expectShoppingCartIsEmpty();
+    });
+
+    testWidgets('Add product with quantity = 5, goes out of stock',
+        (tester) async {
+      final r = Robot(tester);
+      await r.pumpMyApp();
+      await r.products.selectProduct();
+      await r.products.setProductQuantity(5);
+      await r.cart.addToCart();
+      r.cart.expectProductIsOutOfStock();
+    });
+
+    testWidgets(
+        'Add product with quantity = 5, remains out of stock when opened again',
+        (tester) async {
+      final r = Robot(tester);
+      await r.pumpMyApp();
+      await r.products.selectProduct();
+      await r.products.setProductQuantity(5);
+      await r.cart.addToCart();
+      await r.goBack();
+      await r.products.selectProduct();
+      r.cart.expectProductIsOutOfStock();
+    });
+  });
+}