Test Writing Guide

Before Writing ANY Test

1. Search for duplicate scenarios — grep the test directory for similar setups
2. Read the rules file .claude/rules/write-tests.mdc — the 20 rules agents ALWAYS get wrong

Minimal Template

import { expect, test } from "bun:test";
import { type ApiCustomerV3 } from "@autumn/shared";
import { expectCustomerFeatureCorrect } from "@tests/integration/billing/utils/expectCustomerFeatureCorrect";
import { expectStripeSubscriptionCorrect } from "@tests/integration/billing/utils/expectStripeSubCorrect";
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";