import assert from "node:assert/strict";import { test } from "node:test";import { setup } from "./helpers/app.ts";async function withCart() {  const s = setup();  await s.addProduct("wool-socks", { name: "Wool socks", price_cents: 1800, stock: 3 });  await s.addProduct("canvas-tote", { name: "Canvas tote", price_cents: 2400, stock: 10 });  const { body } = await s.call("POST", "/carts");  return { ...s, cartId: body.cart.id as string };}test("a new cart is open and empty", async () => {  const s = await withCart();  const { body } = await s.call("GET", `/carts/${s.cartId}`);  assert.equal(body.cart.status, "open");  assert.deepEqual(body.cart.items, []);  assert.equal(body.cart.total_cents, 0);});test("adds items and totals them with shipping", async () => {  const s = await withCart();  await s.call("PUT", `/carts/${s.cartId}/items/wool-socks`, { quantity: 2 });  const { body } = await s.call("PUT", `/carts/${s.cartId}/items/canvas-tote`, { quantity: 1 });  assert.equal(body.cart.items.length, 2);  assert.equal(body.cart.subtotal_cents, 6000);  assert.equal(body.cart.shipping_cents, 0, "free shipping from $50");  assert.equal(body.cart.total_cents, 6000);});test("charges shipping under the threshold", async () => {  const s = await withCart();  const { body } = await s.call("PUT", `/carts/${s.cartId}/items/wool-socks`, { quantity: 1 });  assert.equal(body.cart.shipping_cents, 595);  assert.equal(body.cart.total_cents, 2395);});test("setting a quantity replaces it, and zero removes the item", async () => {  const s = await withCart();  await s.call("PUT", `/carts/${s.cartId}/items/wool-socks`, { quantity: 2 });  let { body } = await s.call("PUT", `/carts/${s.cartId}/items/wool-socks`, { quantity: 1 });  assert.equal(body.cart.items[0].quantity, 1);  ({ body } = await s.call("DELETE", `/carts/${s.cartId}/items/wool-socks`));  assert.deepEqual(body.cart.items, []);});test("refuses more than are in stock and says how many are left", async () => {  const s = await withCart();  const res = await s.call("PUT", `/carts/${s.cartId}/items/wool-socks`, { quantity: 4 });  assert.equal(res.status, 409);  assert.equal(res.body.error, "out_of_stock");  assert.equal(res.body.available, 3);});test("quantities are whole numbers up to ten", async () => {  const s = await withCart();  for (const quantity of [-1, 1.5, 11, "2"]) {    const res = await s.call("PUT", `/carts/${s.cartId}/items/canvas-tote`, { quantity });    assert.equal(res.status, 400, `quantity ${JSON.stringify(quantity)}`);  }});test("unknown carts and products", async () => {  const s = await withCart();  assert.equal((await s.call("GET", "/carts/nope")).body.error, "cart_not_found");  assert.equal((await s.call("PUT", `/carts/${s.cartId}/items/nope`, { quantity: 1 })).body.error, "product_not_found");});