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[_]: fix/negative amount when calculating taxes #325

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Merged
xabg2 merged 1 commit into from
Nov 25, 2025
Merged

[_]: fix/negative amount when calculating taxes #325

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4 changes: 2 additions & 2 deletions src/controller/checkout.controller.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -467,11 +467,11 @@ export default function (usersService: UsersService, paymentsService: PaymentSer
if (promoCodeName) {
const couponCode = await paymentsService.getPromoCodeByName(price.product, promoCodeName);
if (couponCode.amountOff) {
amount = price.amount - couponCode.amountOff;
amount = Math.max(0, price.amount - couponCode.amountOff);
} else if (couponCode.percentOff) {
const discount = Math.floor((price.amount * couponCode.percentOff) / 100);
const discountedPrice = price.amount - discount;
amount = discountedPrice;
amount = Math.max(0, discountedPrice);
}
}

Expand Down
91 changes: 70 additions & 21 deletions tests/src/controller/checkout.controller.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ beforeEach(() => {
});

describe('Checkout controller', () => {
it('When the jwt verify fails, then an error indicating so is thrown', async () => {
test('When the jwt verify fails, then an error indicating so is thrown', async () => {
const userAuthToken = 'invalid_token';

const response = await app.inject({
Expand All @@ -55,7 +55,7 @@ describe('Checkout controller', () => {
});

describe('Get customer ID', () => {
it('When the user exists in Users collection, then the customer Id associated to the user is returned', async () => {
test('When the user exists in Users collection, then the customer Id associated to the user is returned', async () => {
const mockedUser = getUser();
const userAuthToken = getValidAuthToken(mockedUser.uuid);
const userToken = getValidUserToken({ customerId: mockedUser.customerId });
Expand Down Expand Up @@ -127,7 +127,7 @@ describe('Checkout controller', () => {
expect(insertUserSpy).toHaveBeenCalledWith(insertUserPayload);
});

it('When the user provides country and Vat Id, then they are attached to the user correctly', async () => {
test('When the user provides country and Vat Id, then they are attached to the user correctly', async () => {
const country = 'ES';
const companyVatId = 'vat_id';

Expand Down Expand Up @@ -391,7 +391,7 @@ describe('Checkout controller', () => {
});

describe('Creating a subscription', () => {
it('When the user wants to create a subscription, it is created successfully', async () => {
test('When the user wants to create a subscription, test is created successfully', async () => {
const mockedUser = getUser();
const mockedSubscription = getCreatedSubscription();
const mockedSubscriptionResponse = getCreateSubscriptionResponse();
Expand Down Expand Up @@ -426,7 +426,7 @@ describe('Checkout controller', () => {
});

describe('Handling errors', () => {
it('When the id of the price is not present in the body, then an error indicating so is thrown', async () => {
test('When the id of the price is not present in the body, then an error indicating so is thrown', async () => {
const mockedUser = getUser();
const authToken = getValidAuthToken(mockedUser.uuid);

Expand All @@ -444,7 +444,7 @@ describe('Checkout controller', () => {
expect(response.statusCode).toBe(400);
});

it('When the id of the customer is not present in the body, then an error indicating so is thrown', async () => {
test('When the id of the customer is not present in the body, then an error indicating so is thrown', async () => {
const mockedUser = getUser();
const authToken = getValidAuthToken(mockedUser.uuid);

Expand All @@ -462,7 +462,7 @@ describe('Checkout controller', () => {
expect(response.statusCode).toBe(400);
});

it('When the user token is not present in the body, then an error indicating so is thrown', async () => {
test('When the user token is not present in the body, then an error indicating so is thrown', async () => {
const mockedUser = getUser();
const authToken = getValidAuthToken(mockedUser.uuid);

Expand All @@ -481,7 +481,7 @@ describe('Checkout controller', () => {
expect(response.statusCode).toBe(400);
});

it('When the provided token is invalid or cannot be verified, then an error indicating so is thrown', async () => {
test('When the provided token is invalid or cannot be verified, then an error indicating so is thrown', async () => {
const mockedUser = getUser();
const authToken = getValidAuthToken(mockedUser.uuid);
const invalidUserToken = 'malformed.token.payload';
Expand All @@ -506,7 +506,7 @@ describe('Checkout controller', () => {
expect(response.statusCode).toBe(403);
});

it('When the provided token contains a customerId that does not match the provided customerId, then an error indicating so is thrown', async () => {
test('When the provided token contains a customerId that does not match the provided customerId, then an error indicating so is thrown', async () => {
const mockedUser = getUser();
const authToken = getValidAuthToken(mockedUser.uuid);
const userToken = getValidUserToken({ customerId: 'invalid_customer_id' });
Expand Down Expand Up @@ -566,7 +566,7 @@ describe('Checkout controller', () => {
jest.clearAllMocks();
});

it('When the user wants to pay a one time plan, then an invoice is created and the client secret is returned', async () => {
test('When the user wants to pay a one time plan, then an invoice is created and the client secret is returned', async () => {
const mockedUser = getUser();
const mockedInvoice = getInvoice();
const mockedPrice = priceById({
Expand Down Expand Up @@ -690,7 +690,7 @@ describe('Checkout controller', () => {
expect(response.statusCode).toBe(400);
});

it('When the user already has the max storage allowed, then an error indicating so is thrown', async () => {
test('When the user already has the max storage allowed, then an error indicating so is thrown', async () => {
const mockedUser = getUser();
const mockedInvoice = getInvoice();
const mockedPrice = priceById({
Expand Down Expand Up @@ -765,7 +765,7 @@ describe('Checkout controller', () => {
expect(response.statusCode).toBe(400);
});

it('When the id of the price is not present in the body, then an error indicating so is thrown', async () => {
test('When the id of the price is not present in the body, then an error indicating so is thrown', async () => {
const mockedUser = getUser();
const authToken = getValidAuthToken(mockedUser.uuid);

Expand All @@ -783,7 +783,7 @@ describe('Checkout controller', () => {
expect(response.statusCode).toBe(400);
});

it('When the id of the customer is not present in the body, then an error indicating so is thrown', async () => {
test('When the id of the customer is not present in the body, then an error indicating so is thrown', async () => {
const mockedUser = getUser();
const authToken = getValidAuthToken(mockedUser.uuid);

Expand All @@ -801,7 +801,7 @@ describe('Checkout controller', () => {
expect(response.statusCode).toBe(400);
});

it('When the user token is not present in the body, then an error indicating so is thrown', async () => {
test('When the user token is not present in the body, then an error indicating so is thrown', async () => {
const mockedUser = getUser();
const authToken = getValidAuthToken(mockedUser.uuid);

Expand All @@ -820,7 +820,7 @@ describe('Checkout controller', () => {
expect(response.statusCode).toBe(400);
});

it('When the provided token is invalid or cannot be verified, then an error indicating so is thrown', async () => {
test('When the provided token is invalid or cannot be verified, then an error indicating so is thrown', async () => {
const mockedUser = getUser();
const authToken = getValidAuthToken(mockedUser.uuid);
const invalidUserToken = 'malformed.token.payload';
Expand All @@ -846,7 +846,7 @@ describe('Checkout controller', () => {
expect(response.statusCode).toBe(403);
});

it('When the provided token contains a customerId that does not match the provided customerId, then an error indicating so is thrown', async () => {
test('When the provided token contains a customerId that does not match the provided customerId, then an error indicating so is thrown', async () => {
const mockedUser = getUser();
const authToken = getValidAuthToken(mockedUser.uuid);
const userToken = getValidUserToken({ invoiceId: 'invalid_customer_id' });
Expand Down Expand Up @@ -902,7 +902,7 @@ describe('Checkout controller', () => {
});

describe('Get Price by its ID', () => {
it('When the user wants to get a price by its ID, then the price is returned with its taxes', async () => {
test('When the user wants to get a price by its ID, then the price is returned with its taxes', async () => {
const mockedPrice = priceById({
bytes: 123456789,
interval: 'year',
Expand Down Expand Up @@ -938,7 +938,7 @@ describe('Checkout controller', () => {
});

describe('Handling promo codes', () => {
it('When the user provides a promo code with amount off, then the price is returned with the discount applied', async () => {
test('When the user provides a promo code with amount off, then the price is returned with the discount applied', async () => {
const mockedPrice = priceById({
bytes: 123456789,
interval: 'year',
Expand Down Expand Up @@ -982,7 +982,7 @@ describe('Checkout controller', () => {
});
});

it('When the user provides a promo code with percent off, then the price is returned with the discount applied', async () => {
test('When the user provides a promo code with percent off, then the price is returned with the discount applied', async () => {
const mockedPrice = priceById({
bytes: 123456789,
interval: 'year',
Expand Down Expand Up @@ -1026,10 +1026,59 @@ describe('Checkout controller', () => {
},
});
});

test('When the user provides a promo code with a discount that is more than the product price, then the price should be 0 instead of a negative price', async () => {
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@sg-gs sg-gs Nov 25, 2025

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To not block you know, I will leave it as a suggestion: if the controller allows it (because it is valid), consider handling these things at the business case level the next time (services/domains).

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@xabg2 xabg2 Nov 25, 2025

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I'll keep that in mind. Thanks for the feedback! 🙌🏽

const mockedPrice = {
...priceById({
bytes: 123456789,
interval: 'year',
}),
amount: 14000,
decimalAmount: 140,
};
const promoCode = {
promoCodeName: 'promo_code_name',
amountOff: 15000,
percentOff: null,
codeId: 'promo_code_id',
};

const discountedAmount = 0;
const taxes = mockCalculateTaxFor(discountedAmount);

jest.spyOn(PaymentService.prototype, 'getPriceById').mockResolvedValue(mockedPrice);
jest.spyOn(PaymentService.prototype, 'getPromoCodeByName').mockResolvedValue(promoCode);
jest
.spyOn(PaymentService.prototype, 'calculateTax')
.mockResolvedValueOnce(taxes as unknown as Stripe.Tax.Calculation);

const response = await app.inject({
path: `/checkout/price-by-id`,
query: {
priceId: mockedPrice.id,
promoCodeName: promoCode.promoCodeName,
userAddress: '123.12.12.12',
},
method: 'GET',
});

const responseBody = response.json();

expect(response.statusCode).toBe(200);
expect(responseBody).toStrictEqual({
price: mockedPrice,
taxes: {
tax: taxes.tax_amount_exclusive,
decimalTax: taxes.tax_amount_exclusive / 100,
amountWithTax: taxes.amount_total,
decimalAmountWithTax: taxes.amount_total / 100,
},
});
});
});

describe('Handling errors', () => {
it('When the priceId is not present in the query, then an error indicating so is thrown', async () => {
test('When the priceId is not present in the query, then an error indicating so is thrown', async () => {
const response = await app.inject({
path: '/checkout/price-by-id',
method: 'GET',
Expand All @@ -1040,7 +1089,7 @@ describe('Checkout controller', () => {
});

describe('User address, country and postal code are not provided', () => {
it('When any of user location params are provided, then the price is returned with taxes to 0', async () => {
test('When any of user location params are provided, then the price is returned with taxes to 0', async () => {
const mockedPrice = priceById({
bytes: 123456789,
interval: 'year',
Expand Down
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