write-test

What I do

Write integration tests for the Autumn billing system using the initScenario pattern.

Before Writing Any Test

ALWAYS check for duplicate test scenarios FIRST:

1. •Search the test directory for similar scenarios using Grep with relevant keywords (e.g., new_billing_subscription, cancel.*addon, feature names)
2. •If a duplicate or very similar scenario exists, WARN the user and ask for confirmation before proceeding
3. •Only proceed with writing the test after confirming it's not a duplicate

ALWAYS read these codebase files FIRST:

1. •server/tests/TEST_GUIDE.md - Core patterns, fixtures, scenario builder
2. •For billing tests: server/tests/integration/billing/update-subscription/BILLING_GUIDE.md

Critical Rules

DO:

• •ALWAYS use test.concurrent() for ALL tests - never use plain test(). This enables parallel execution.
• •Use initScenario with s.* builders
• •Use product.id in s.attach() (never string literals)
• •Use Decimal.js for balance calculations in track tests
• •Unique customerId per test
• •Use generic types with AutumnInt: autumnV1.customers.get<ApiCustomerV3>(), autumnV1.check<CheckResponseV1>()
• •USE UTILITY FUNCTIONS WHENEVER POSSIBLE - the shorter the code, the better. Check server/tests/integration/billing/utils/ for existing utilities like expectCustomerProducts, expectProductScheduled, expectCustomerInvoiceCorrect, etc.

DON'T:

• •Use plain test() - ALWAYS use test.concurrent()
• •Use describe/beforeAll/test (legacy pattern)
• •Use Date.now() with test clocks (use advancedTo)
• •Share state between tests
• •Use raw arithmetic for balance calculations (floating point errors)
• •Use as unknown as Type casting - use generic types instead
• •Write manual assertion loops when a utility function exists

AutumnInt Response Types

Minimal Template

import { expect, test } from "bun:test";
import { type ApiCustomerV3 } from "@autumn/shared";
import { expectCustomerFeatureCorrect } from "@tests/integration/billing/utils/expectCustomerFeatureCorrect";
import { TestFeature } from "@tests/setup/v2Features.js";
import { items } from "@tests/utils/fixtures/items.js";
import { products } from "@tests/utils/fixtures/products.js";
import { initScenario, s } from "@tests/utils/testInitUtils/initScenario.js";
import chalk from "chalk";

test.concurrent(`${chalk.yellowBright("feature: description")}`, async () => {
  const messagesItem = items.monthlyMessages({ includedUsage: 100 });
  const pro = products.base({ id: "pro", items: [messagesItem] });

  const { customerId, autumnV1 } = await initScenario({
    customerId: "unique-test-id",
    setup: [s.customer({ paymentMethod: "success" }), s.products({ list: [pro] })],
    actions: [s.attach({ productId: pro.id })],
  });

  const customer = await autumnV1.customers.get<ApiCustomerV3>(customerId);
  expectCustomerFeatureCorrect({ customer, featureId: TestFeature.Messages, balance: 100 });
});

References

Load these on-demand for detailed information:

• •references/SCENARIO.md - Scenario initialization, product configs, s.* builders
• •references/FIXTURES.md - Item and product fixtures with all params
• •references/ENTITIES.md - Entity-based testing (multi-tenant, per-entity billing)
• •references/TRACK-CHECK.md - Track/check endpoint testing, credit systems, Decimal.js
• •references/EXPECTATIONS.md - All expectation utilities
• •references/GOTCHAS.md - Common pitfalls, debugging, billing edge cases
• •references/WEBHOOKS.md - Outbound webhook testing with Svix Play
• •references/STRIPE-BEHAVIORS.md - Stripe webhook behaviors for consumables, trials, cancellations

File Location

Tests: server/tests/integration/billing/ organized by feature area.

Run Tests

bun test path/to/file.test.ts