[Woo POS] Coupons: Disallow adding duplicate coupons to cart

WooCommerce/Classes/POS/Models/Cart.swift

@@ -49,7 +49,9 @@ extension Cart {
         case .variableParentProduct:
             return
         case .coupon(let coupon):
-            let couponItem = Cart.CouponItem(id: UUID(), code: coupon.code, summary: coupon.summary)
+            guard !coupons.contains(where: { $0.id == coupon.id }) else { return }
+
+            let couponItem = Cart.CouponItem(id: coupon.id, code: coupon.code, summary: coupon.summary)
             coupons.insert(couponItem, at: coupons.startIndex)
         }
     }

WooCommerce/Classes/POS/Presentation/Item Selector/POSItemActionHandler.swift

@@ -51,6 +51,28 @@ final class StandardPOSItemActionHandler: POSItemActionHandler {
     }
 }
 
+@available(iOS 17.0, *)
+final class CouponsItemActionHandler: POSItemActionHandler {
+    private let posModel: PointOfSaleAggregateModelProtocol
+    private let analytics: Analytics
+    private let itemListType: ItemListType
+
+    init(posModel: PointOfSaleAggregateModelProtocol, itemListType: ItemListType, analytics: Analytics = ServiceLocator.analytics) {
+        self.posModel = posModel
+        self.itemListType = itemListType
+        self.analytics = analytics
+    }
+
+    func handleTap(_ item: POSItem) {
+        let alreadyExists = posModel.cart.coupons.contains(where: { $0.id == item.id })
+        if alreadyExists {
+            return
+        }
+        posModel.addToCart(item)
+        trackTapAnalytics(for: item, itemListType: itemListType, using: analytics)
+    }
+}
+
 /// Handler for handling taps on search result items, saving the search term
 @available(iOS 17.0, *)
 final class SearchResultItemActionHandler: POSItemActionHandler {

WooCommerce/WooCommerceTests/POS/Models/PointOfSaleAggregateModelTests.swift

@@ -243,14 +243,7 @@ struct PointOfSaleAggregateModelTests {
         }
 
         @available(iOS 17.0, *)
-        @Test(.disabled(
-            """
-            This test doesn't currently work; analytics extensions are not thread-safe,
-            and using the MainActor means the assert happens too early. I don't think
-            we want the addToCart to be async, but that would be one way to fix it.
-            """))
-        func addToCart_tracks_analytics_event() async throws {
-            // Given
+        @Test func addToCart_when_attempt_to_add_duplicated_coupon_then_does_not_add_it_to_cart() {
             let sut = PointOfSaleAggregateModel(itemsController: MockPointOfSaleItemsController(),
                                                 purchasableItemsSearchController: MockPointOfSalePurchasableItemsSearchController(),
                                                 couponsController: MockPointOfSaleCouponsController(),
@@ -261,14 +254,14 @@ struct PointOfSaleAggregateModelTests {
                                                 collectOrderPaymentAnalyticsTracker: MockPOSCollectOrderPaymentAnalyticsTracker(),
                                                 searchHistoryService: MockPOSSearchHistoryService(),
                                                 popularItemsController: MockPointOfSalePopularItemsController())
-            let item = makePurchasableItem()
+            let coupon = makeCouponItem(code: "DISCOUNT!")
 
             // When
-            sut.addToCart(item)
+            sut.addToCart(coupon)
+            sut.addToCart(coupon)
 
             // Then
-            let event = try #require(analyticsProvider.receivedEvents.first)
-            #expect(event == "item_added_to_cart")
+            #expect(sut.cart.coupons.count == 1)
         }
     }