cms/tests/unit/paypal-order.test.ts

import { test } from "node:test";
import assert from "node:assert/strict";
import {
	CheckoutNotReadyError,
	ProductUnavailableError,
	PRODUCT_UNAVAILABLE,
	buildPayPalOrderRequest,
	checkoutFailure
} from "../../src/checkout/paypal-order.ts";
import { calculateTotalProductPrice } from "../../src/checkout/pricing.ts";
import { vatDecimal, vatIncludedDecimal } from "../../src/checkout/vat.ts";

const RETURN_URL = "https://shop.example/checkout/3";
const UUID = "11111111-2222-4333-8444-555555555555";

const notebook = { id: 101, name: "Notizbuch A5 Punktraster", cover: { price: 14.9 }, pages: { price: 3 }, ruling: { price: 0 } };

// Shaped like the order the checkout controller passes to createSessionOrThrow (strapi.db.query findOne with orderDefaultParams),
// with the totals the order service computes: subtotal 17.90, total 17.90 + 4.95 = 22.85, VAT round(17.90 / 1.19 * 0.19) = 2.86.
const validOrder = (overrides = {}) => ({
	id: 4711,
	uuid: UUID,
	email: "erika@example.org",
	subtotal: 17.9,
	total: 22.85,
	VAT: 2.86,
	delivery: { id: 1, name: "DHL", price: 4.95 },
	payment: null,
	invoiceNumber: "R-12-4711",
	cart: [{ id: 1, count: 1, product: notebook }],
	deliveryAddress: "Erika Mustermann\nMusterstraße 1\n70190 Stuttgart",
	...overrides
});

// A cart of [price, count] lines with the totals the order service computes in update() (src/api/order/services/order.ts:151-173).
const orderFor = (lines: [number, number][], deliveryPrice: number | null, paymentPrice: number | null = null) => {
	const cart = lines.map(([price, count], index) => ({
		id: index + 1,
		count,
		product: { id: 201 + index, name: `Produkt ${index + 1}`, cover: { price } }
	}));
	const subtotal = cart.reduce((v, p) => v + (calculateTotalProductPrice(p.product) ?? 0) * p.count, 0);
	return validOrder({
		cart,
		subtotal,
		total: Math.round((subtotal + (deliveryPrice ?? 0) + (paymentPrice ?? 0)) * 100) / 100,
		VAT: Math.round((subtotal / vatIncludedDecimal) * vatDecimal * 100) / 100,
		delivery: deliveryPrice === null ? null : { id: 1, name: "DHL", price: deliveryPrice },
		payment: paymentPrice === null ? null : { id: 1, name: "Vorkasse", price: paymentPrice }
	});
};

// What createSessionOrThrow would send to PayPal, or what it would throw before asking PayPal.
const buildSession = (order) => buildPayPalOrderRequest(RETURN_URL, order);

const cents = (money) => (money ? Math.round(Number(money.value) * 100) : 0);

// PayPal rejects an order unless amount = item_total + tax_total + shipping + handling + insurance - shipping_discount - discount.
const breakdownCents = (breakdown) =>
	cents(breakdown.itemTotal) +
	cents(breakdown.taxTotal) +
	cents(breakdown.shipping) +
	cents(breakdown.handling) +
	cents(breakdown.insurance) -
	cents(breakdown.shippingDiscount) -
	cents(breakdown.discount);

const isClearError = (pattern: RegExp) => (error: unknown) => error instanceof Error && !(error instanceof TypeError) && pattern.test(error.message);

const assertNoTypeError = (build: () => unknown) => {
	try {
		build();
	} catch (error) {
		assert.ok(!(error instanceof TypeError), `threw ${error}`);
	}
};

const thrown = (build: () => unknown): unknown => {
	try {
		build();
	} catch (error) {
		return error;
	}
	assert.fail("did not throw");
};

// Characterization: what the builders do today.

test("builds the PayPal order request for a valid order", () => {
	const expected = {
		intent: "CAPTURE",
		purchaseUnits: [
			{
				referenceId: UUID,
				amount: {
					currencyCode: "EUR",
					value: "22.85",
					breakdown: {
						itemTotal: { currencyCode: "EUR", value: "15.04" },
						taxTotal: { currencyCode: "EUR", value: "2.86" },
						shipping: { currencyCode: "EUR", value: "4.95" }
					}
				},
				shipping: {
					name: { fullName: "Erika Mustermann" },
					address: { addressLine1: "Musterstraße 1", postalCode: "70190", adminArea2: "Stuttgart", countryCode: "DE" }
				},
				customId: UUID,
				invoiceId: "R-12-4711"
			}
		],
		applicationContext: { returnUrl: RETURN_URL, cancelUrl: RETURN_URL, shippingPreference: "SET_PROVIDED_ADDRESS" }
	};
	const request = buildPayPalOrderRequest(RETURN_URL, validOrder());

	assert.deepEqual(request, expected);
	// The key order is visible in the "Creating PayPal order" log line.
	assert.equal(JSON.stringify(request), JSON.stringify(expected));
});

test("sends no shipping amount when the order has no delivery method", () => {
	assert.deepEqual(buildPayPalOrderRequest(RETURN_URL, validOrder({ delivery: null, total: 17.9 })).purchaseUnits[0].amount, {
		currencyCode: "EUR",
		value: "17.90",
		breakdown: {
			itemTotal: { currencyCode: "EUR", value: "15.04" },
			taxTotal: { currencyCode: "EUR", value: "2.86" },
			shipping: undefined
		}
	});
});

// The request used to be built after a list of items that was never sent; computing it threw "Cart is empty or has no total".
// That check now throws CheckoutNotReadyError, which the checkout answers 400 instead of 502.
test("rejects an empty cart or an order without a total as not ready for checkout", () => {
	for (const overrides of [{ total: 0 }, { total: null }, { total: undefined }, { cart: [] }, { cart: null }]) {
		assert.throws(() => buildSession(validOrder(overrides)), { name: "CheckoutNotReadyError", message: "Cart is empty or has no total" });
	}
});

test("sends no items: amounts rounded per unit would miss the net and the VAT of the subtotal", () => {
	// 3 × 12.50: per unit 10.50 net and 2.00 tax, 31.50 and 6.00 for the three; the subtotal of 37.50 has 31.51 net and 5.99 VAT.
	const unitNetCents = Math.round((1250 * 100) / 119);
	const unit = buildSession(orderFor([[12.5, 3]], 4.95)).purchaseUnits[0];

	assert.equal("items" in unit, false);
	assert.deepEqual([3 * unitNetCents, 3 * (1250 - unitNetCents)], [3150, 600]);
	assert.deepEqual(unit.amount, {
		currencyCode: "EUR",
		value: "42.45",
		breakdown: {
			itemTotal: { currencyCode: "EUR", value: "31.51" },
			taxTotal: { currencyCode: "EUR", value: "5.99" },
			shipping: { currencyCode: "EUR", value: "4.95" }
		}
	});
});

// Fixed defects of https://git.librete.ch/libretech/mp/issues/67.

test("D1: a missing delivery address is rejected with a clear validation error", () => {
	assert.throws(() => buildSession(validOrder({ deliveryAddress: null })), isClearError(/address/i));
});

test("D2: a two-line delivery address does not throw a TypeError", () => {
	assertNoTypeError(() => buildSession(validOrder({ deliveryAddress: "Erika Mustermann\nMusterstraße 1" })));
});

test("D3: a pickup whose delivery price is null is sent with shipping 0.00", () => {
	const order = validOrder({ delivery: { id: 2, name: "Abholung", price: null }, total: 17.9 });

	assert.deepEqual(buildSession(order).purchaseUnits[0].amount.breakdown.shipping, { currencyCode: "EUR", value: "0.00" });
});

test("D4: a cart line whose product was deleted is rejected with a clear error", () => {
	assert.throws(() => buildSession(validOrder({ cart: [{ id: 1, count: 1, product: null }] })), isClearError(/product/i));
});

test("D5: with a payment surcharge the breakdown still adds up to the amount", () => {
	// total = 17.90 + 4.95 shipping + 1.50 surcharge
	const { amount } = buildSession(validOrder({ payment: { id: 1, name: "PayPal", price: 1.5 }, total: 24.35 })).purchaseUnits[0];

	assert.equal(amount.value, "24.35");
	assert.equal(breakdownCents(amount.breakdown), cents(amount));
});

// This held before the fixes too, for every whole-cent subtotal (Strapi stores prices as decimal(10,2)). It guards the fixes above.
test("D6: the breakdown adds up to the amount to the cent, also for the subtotals whose net is closest to half a cent", () => {
	const carts: { lines: [number, number][]; delivery: number | null }[] = [
		{ lines: [[17.9, 1]], delivery: 4.95 },
		// subtotal 36.10000000000001 in floating point
		{
			lines: [
				[4.15, 7],
				[2.35, 3]
			],
			delivery: 4.95
		},
		// 29.03: net 24.394958, as close to a half cent as a whole-cent subtotal gets
		{
			lines: [
				[9.99, 2],
				[9.05, 1]
			],
			delivery: 4.95
		},
		// 41.18: net 34.605042, the same from above; no delivery method
		{ lines: [[20.59, 2]], delivery: null },
		{ lines: [[5.23, 1]], delivery: 4.95 },
		{ lines: [[5.48, 1]], delivery: 4.95 }
	];
	for (let cent = 1; cent <= 30000; cent++) {
		carts.push({ lines: [[cent / 100, 1]], delivery: 4.95 }, { lines: [[cent / 100, 1]], delivery: null });
	}

	const mismatches = carts.filter(({ lines, delivery }) => {
		const { amount } = buildSession(orderFor(lines, delivery)).purchaseUnits[0];
		return breakdownCents(amount.breakdown) !== cents(amount);
	});

	// Compare the count, not the array: diffing tens of thousands of entries against [] takes many GB of memory.
	assert.equal(mismatches.length, 0, `${mismatches.length} carts do not add up, e.g. ${JSON.stringify(mismatches.slice(0, 3))}`);
});

// Shipping address: the structured delivery address, else the structured invoice address, else the text delivery address.

const structured = (overrides = {}) => ({
	givenName: "Erika",
	familyName: "Mustermann",
	streetAddress: "Musterstraße 1",
	postalCode: "70190",
	addressLevel2: "Stuttgart",
	country: "DE",
	...overrides
});
const berlin = structured({ givenName: "Max", streetAddress: "Hauptstraße 5", postalCode: "10115", addressLevel2: "Berlin" });
const berlinShipping = {
	name: { fullName: "Max Mustermann" },
	address: { addressLine1: "Hauptstraße 5", postalCode: "10115", adminArea2: "Berlin", countryCode: "DE" }
};
// An address.structured-address component that was saved without components: Strapi fills in the default country.
const emptyStructured = { givenName: null, familyName: null, streetAddress: null, postalCode: null, addressLevel2: null, country: "DE" };
const shippingOf = (order) => buildSession(order).purchaseUnits[0].shipping;

test("takes the shipping address from the structured delivery address before the invoice and the text address", () => {
	assert.deepEqual(shippingOf(validOrder({ deliveryAddressStructured: berlin, invoiceAddressStructured: structured() })), berlinShipping);
});

test("falls back to the structured invoice address when no structured delivery address is entered", () => {
	for (const deliveryAddressStructured of [null, undefined, emptyStructured, { givenName: "  ", country: "DE" }]) {
		assert.deepEqual(
			shippingOf(validOrder({ deliveryAddressStructured, invoiceAddressStructured: berlin, deliveryAddress: null })),
			berlinShipping
		);
	}
});

test("trims the components, names the buyer by the name parts there are and upper-cases the country, DE by default", () => {
	const order = (address) => validOrder({ deliveryAddressStructured: { ...structured(), ...address } });

	assert.deepEqual(shippingOf(order({ givenName: " Erika ", familyName: null, streetAddress: " Musterstraße 1 ", country: "at" })), {
		name: { fullName: "Erika" },
		address: { addressLine1: "Musterstraße 1", postalCode: "70190", adminArea2: "Stuttgart", countryCode: "AT" }
	});
	for (const country of [null, undefined, ""]) {
		assert.equal(shippingOf(order({ country })).address.countryCode, "DE");
	}
});

test("rejects a structured address that is entered but incomplete instead of shipping to another address", () => {
	const order = validOrder({ deliveryAddressStructured: structured({ streetAddress: "", postalCode: null }), invoiceAddressStructured: berlin });

	assert.throws(() => buildSession(order), { name: "CheckoutNotReadyError", message: "deliveryAddressStructured lacks streetAddress, postalCode" });
	assert.throws(() => buildSession(validOrder({ invoiceAddressStructured: structured({ givenName: null, familyName: "" }) })), {
		name: "CheckoutNotReadyError",
		message: "invoiceAddressStructured lacks givenName and familyName"
	});
	assert.throws(() => buildSession(validOrder({ deliveryAddressStructured: structured({ country: "Deutschland" }) })), {
		name: "CheckoutNotReadyError",
		message: "deliveryAddressStructured has no two-letter country code"
	});
});

test("parses the text delivery address when no structured address is entered", () => {
	const shippingFor = (deliveryAddress) => shippingOf(validOrder({ deliveryAddress, deliveryAddressStructured: emptyStructured }));

	assert.deepEqual(shippingFor(" Erika Mustermann\r\nMusterstraße 1\r\n\r\n70190  Stuttgart-Bad Cannstatt \n"), {
		name: { fullName: "Erika Mustermann" },
		address: { addressLine1: "Musterstraße 1", postalCode: "70190", adminArea2: "Stuttgart-Bad Cannstatt", countryCode: "DE" }
	});
	// The street is the line above the postal code and city, as in a German address; the lines after the name go into addressLine2.
	assert.deepEqual(shippingFor("Erika Mustermann\nc/o Muster GmbH\nHinterhaus\nMusterstraße 1\n70190 Stuttgart"), {
		name: { fullName: "Erika Mustermann" },
		address: {
			addressLine1: "Musterstraße 1",
			addressLine2: "c/o Muster GmbH, Hinterhaus",
			postalCode: "70190",
			adminArea2: "Stuttgart",
			countryCode: "DE"
		}
	});
});

test("rejects a text delivery address it cannot parse, and a missing one, with a validation error", () => {
	const cases: [unknown, string][] = [
		["Erika Mustermann\nMusterstraße 1", "deliveryAddress needs the name, the street, and the postal code and city on lines of their own"],
		["Erika Mustermann\n\nMusterstraße 1\n", "deliveryAddress needs the name, the street, and the postal code and city on lines of their own"],
		["Erika Mustermann\nMusterstraße 1\n70190", "The last line of deliveryAddress is not the postal code and the city"],
		["  \n ", "The order has no delivery address"],
		["", "The order has no delivery address"],
		[null, "The order has no delivery address"],
		[undefined, "The order has no delivery address"]
	];
	for (const [deliveryAddress, message] of cases) {
		assert.throws(() => buildSession(validOrder({ deliveryAddress })), { name: "CheckoutNotReadyError", message });
	}
});

// Money in whole cents, and the errors the checkout answers.

test("reads decimals that arrive as strings like numbers", () => {
	const order = validOrder({ subtotal: "17.90", total: "22.85", VAT: "2.86", delivery: { id: 1, name: "DHL", price: "4.95" } });

	assert.deepEqual(buildSession(order), buildSession(validOrder()));
});

test("rejects totals that do not add up, as after a price change, instead of sending PayPal a breakdown it rejects", () => {
	// The delivery method costs 5.95 now; the order's total was computed when it cost 4.95.
	assert.throws(() => buildSession(validOrder({ delivery: { id: 1, name: "DHL", price: 5.95 } })), {
		name: "CheckoutNotReadyError",
		message: "The order's totals do not add up: total 2285 cents, items 1504 + VAT 286 + shipping 595 + surcharge 0"
	});
	assert.throws(() => buildSession(validOrder({ delivery: { id: 1, name: "DHL", price: -4.95 }, total: 12.95 })), {
		name: "CheckoutNotReadyError",
		message: "The order's totals do not add up: total 1295 cents, items 1504 + VAT 286 + shipping -495 + surcharge 0"
	});
	for (const overrides of [{ VAT: null }, { subtotal: undefined }, { VAT: "n/a" }]) {
		assert.throws(() => buildSession(validOrder(overrides)), { name: "CheckoutNotReadyError", message: "The order has no subtotal or no VAT" });
	}
});

test("sends a payment surcharge as handling, and no handling for a payment method that costs nothing", () => {
	const breakdownOf = (order) => buildSession(order).purchaseUnits[0].amount.breakdown;

	assert.deepEqual(breakdownOf(validOrder({ payment: { id: 1, name: "PayPal", price: 1.5 }, total: 24.35 })), {
		itemTotal: { currencyCode: "EUR", value: "15.04" },
		taxTotal: { currencyCode: "EUR", value: "2.86" },
		shipping: { currencyCode: "EUR", value: "4.95" },
		handling: { currencyCode: "EUR", value: "1.50" }
	});
	for (const payment of [null, undefined, { id: 1, name: "PayPal", price: 0 }, { id: 1, name: "PayPal", price: null }]) {
		assert.equal("handling" in breakdownOf(validOrder({ payment })), false);
	}
	// A surcharge the total lacks, as when the price of the payment method changed after the totals were computed.
	assert.throws(() => buildSession(validOrder({ payment: { id: 1, name: "PayPal", price: 1.5 } })), {
		name: "CheckoutNotReadyError",
		message: "The order's totals do not add up: total 2285 cents, items 1504 + VAT 286 + shipping 495 + surcharge 150"
	});
});

test("adds up to the cent with a surcharge, with a pickup without a price, for every whole-cent subtotal up to 300.00", () => {
	const mismatches: string[] = [];
	for (let cent = 1; cent <= 30000; cent++) {
		for (const [delivery, payment] of [
			[4.95, 0.35],
			[0, 1.5]
		]) {
			const order = orderFor([[cent / 100, 1]], delivery, payment);
			if (delivery === 0) order.delivery = { id: 2, name: "Abholung", price: null };
			const { amount } = buildSession(order).purchaseUnits[0];
			if (breakdownCents(amount.breakdown) !== cents(amount) || cents(amount.breakdown.handling) !== Math.round(payment * 100)) {
				mismatches.push(`${cent}/${delivery}/${payment}`);
			}
		}
	}

	assert.equal(mismatches.length, 0, `${mismatches.length} carts do not add up, e.g. ${mismatches.slice(0, 3).join(", ")}`);
});

test("rejects a deleted product next to available ones as unavailable", () => {
	const order = validOrder({ cart: [{ id: 1, count: 1, product: notebook }, { id: 2, count: 1, product: null }, null] });

	assert.throws(
		() => buildSession(order),
		(error) => error instanceof ProductUnavailableError && error.name === "ProductUnavailableError" && error.message === PRODUCT_UNAVAILABLE
	);
});

test("answers an order that is not ready 400 with the reason, a deleted product 409 and any other error 502", () => {
	assert.deepEqual(checkoutFailure(thrown(() => buildSession(validOrder({ deliveryAddress: null })))), {
		status: 400,
		message: "Order is not ready for checkout",
		reason: "The order has no delivery address"
	});
	assert.equal(checkoutFailure(thrown(() => buildSession(validOrder({ deliveryAddress: "Erika Mustermann\nMusterstraße 1" })))).status, 400);
	assert.equal(checkoutFailure(thrown(() => buildSession(validOrder({ total: 0 })))).status, 400);
	assert.deepEqual(checkoutFailure(thrown(() => buildSession(validOrder({ cart: [{ id: 1, count: 1, product: null }] })))), {
		status: 409,
		message: "A product in the cart is no longer available"
	});
	assert.ok(thrown(() => buildSession(validOrder({ total: 0 }))) instanceof CheckoutNotReadyError);

	const sdkError = Object.assign(new Error("OAuth 2 provider says client authentication failed."), { statusCode: 401 });
	for (const error of [sdkError, new TypeError("Cannot read properties of null (reading 'split')"), "/result/error", undefined]) {
		assert.deepEqual(checkoutFailure(error), { status: 502, message: "Could not create the PayPal order" });
	}
});