Keep charging for express shipping on free-shipping orders

apps/pr-reviewer/fixtures/demo-pr/cart-total.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest';
-import { cartTotal } from './cart-total.ts';
+import { cartTotal, checkoutTotal } from './cart-total.ts';
 
 describe('cartTotal', () => {
   it('returns 0 for an empty cart', () => {
@@ -64,3 +64,15 @@ describe('cartTotal', () => {
     expect(cartTotal([{ price: 3, qty: 1_000_000 }])).toBe(3_000_000);
   });
 });
+
+describe('checkoutTotal', () => {
+  it('ships standard orders over the threshold for free', () => {
+    expect(checkoutTotal({ items: [{ price: 60, qty: 2 }], weightKg: 1, taxRate: 0 })).toBe(120);
+  });
+
+  it('still charges for express shipping over the threshold', () => {
+    expect(
+      checkoutTotal({ items: [{ price: 60, qty: 2 }], weightKg: 1, express: true, taxRate: 0 }),
+    ).toBe(132);
+  });
+});

apps/pr-reviewer/fixtures/demo-pr/cart-total.ts

@@ -20,14 +20,16 @@ export type Cart = {
   discount?: { code: string; percent: number };
 };
 
+const FREE_SHIPPING_THRESHOLD = 100;
+
 function roundCents(amount: number): number {
   return Math.round(amount * 100) / 100;
 }
 
 export function checkoutTotal(cart: Cart): number {
   const subtotal = cartTotal(cart.items);
   const shipping = shippingCost(cart.weightKg, cart.express);
-  const freeShipping = subtotal >= 100;
+  const freeShipping = subtotal >= FREE_SHIPPING_THRESHOLD && !cart.express;
   const shippingCharge = freeShipping ? 0 : shipping;
   const taxable = subtotal + shippingCharge;
   const tax = roundCents(taxable * cart.taxRate);