init

backend/src/utils/cart/getQtyByVariantIdFromCart.spec.ts

@@ -0,0 +1,22 @@
+import { getQtyByVariantIdFromCart } from './getQtyByVariantIdFromCart';
+
+describe('getQtyByVariantIdFromCart', () => {
+    it('returns an empty map for an empty cart', () => {
+        expect(getQtyByVariantIdFromCart([])).toEqual(new Map());
+    });
+
+    it('sums quantities for duplicate variant rows', () => {
+        expect(
+            getQtyByVariantIdFromCart([
+                { variantId: 'variant-1', qty: 2 },
+                { variantId: 'variant-1', qty: 3 },
+                { variantId: 'variant-2', qty: 1 }
+            ])
+        ).toEqual(
+            new Map([
+                ['variant-1', 5],
+                ['variant-2', 1]
+            ])
+        );
+    });
+});

backend/src/utils/cart/getQtyByVariantIdFromCart.ts

@@ -0,0 +1,11 @@
+import type { CookieCart } from '../../modules/storefrontCore/types/cart/CookieCart';
+
+export const getQtyByVariantIdFromCart = (cart: CookieCart): Map<string, number> => {
+    const map = new Map<string, number>();
+
+    for (const line of cart) {
+        map.set(line.variantId, (map.get(line.variantId) ?? 0) + line.qty);
+    }
+
+    return map;
+};

backend/src/utils/cart/getTotalCartQtyFromCart.spec.ts

@@ -0,0 +1,16 @@
+import { getTotalCartQtyFromCart } from './getTotalCartQtyFromCart';
+
+describe('getTotalCartQtyFromCart', () => {
+    it('returns zero for an empty cart', () => {
+        expect(getTotalCartQtyFromCart([])).toBe(0);
+    });
+
+    it('sums line quantities', () => {
+        expect(
+            getTotalCartQtyFromCart([
+                { variantId: 'variant-1', qty: 2 },
+                { variantId: 'variant-2', qty: 3 }
+            ])
+        ).toBe(5);
+    });
+});

backend/src/utils/cart/getTotalCartQtyFromCart.ts

@@ -0,0 +1,3 @@
+import type { CookieCart } from '../../modules/storefrontCore/types/cart/CookieCart';
+
+export const getTotalCartQtyFromCart = (cart: CookieCart): number => cart.reduce((sum, line) => sum + line.qty, 0);