testing-bun

name	testing-bun
description	CRITICAL - Invoke BEFORE writing ANY test code. Use when creating new tests, adding test cases, modifying existing tests, writing `it()` or `describe()` blocks, or touching any `*.test.ts` or `*.spec.ts` file. Enforces no try-catch in positive tests, no early returns, no test skipping.
allowed-tools	["Read","Edit","Grep","Glob","Bash"]

Testing Standards (Bun)

Framework

• Use bun:test imports (describe, test, expect, etc.)
• Use Bun test runner, typically via workspace scripts (bun run test)
• Do not introduce Vitest or Jest in this repo
• For local e2e/integration runs, provide required env vars through the shell or .env

Test Strategy

• Default to API integration tests against real infrastructure (real Postgres, real ClickHouse). Call a real endpoint, let data flow through the API into the DB, then verify by calling another endpoint. This is "e2e" from the API perspective only — frontend is out of scope here.
• Never mock services, DB clients, or external APIs. If a test would need a mock, write the integration test instead.
• Unit tests are reserved for pure logical utilities (parsers, formatters, pure functions). A service that "needs" a unit test is a smell — prefer the integration path above.

Critical Rules

1. No Try/Catch in Positive Tests

// Bad - Hides real errors
test('creates user', async () => {
  try {
    const user = await createUser(input)
    expect(user.id).toBeDefined()
  } catch (error) {
    console.error(error)
  }
})

// Good - Let test framework handle errors
test('creates user', async () => {
  const user = await createUser(input)
  expect(user.id).toBeDefined()
})

// Good - Only for testing expected failures
test('rejects invalid input', async () => {
  await expect(createUser(invalid)).rejects.toThrow('Invalid email')
})

2. No Early Returns in Tests

// Bad - Silently skips test
test('calls API', async () => {
  if (!hasCredentials) return
  await callApi()
})

// Good - Fail when preconditions missing
test('calls API', async () => {
  expect(hasCredentials).toBe(true)
  await callApi()
})

3. No Hidden Skips for Missing Env Vars

// Bad
describe.skipIf(!process.env.CLICKHOUSE_URL)('integration', () => {})

// Bad
if (!process.env.CLICKHOUSE_URL) {
  test.skip('requires CLICKHOUSE_URL', () => {})
}

// Good - Let tests fail if env not configured
describe('integration', () => {
  const url = process.env.CLICKHOUSE_URL
  expect(url).toBeTruthy()
})

4. E2E Policy (Mandatory)

• E2E tests must never be conditional on env availability
• Never use skip, skipIf, guard return, or branching that bypasses e2e execution when env vars are absent
• Missing required env vars must cause test failure immediately
• Local e2e execution must provide the required vars through the shell or .env

# Required local command for env-dependent suites
bun run test:integration

5. Prefer Inline Setup Over beforeEach

// Bad - Unnecessary beforeEach
describe('Tests', () => {
  let queryBuilder: QueryBuilder
  beforeEach(() => {
    queryBuilder = new QueryBuilder(schema)
  })
})

// Good - Inline initialization
describe('Tests', () => {
  const queryBuilder = new QueryBuilder(schema)
})

// Good - Use beforeEach only for async cleanup
beforeEach(async () => {
  await client.query('DELETE FROM test_table')
})

Best Practices

Use assert() for Type Narrowing

// Good - Provides type narrowing
assert(checkoutRecord)

Keep Tests Deterministic and Isolated

• Prefer plain test(...) blocks with explicit setup
• Use package-level scripts (bun test src) for focused runs when needed

Environment Variables

When adding new env vars for tests, update:

1. Package's turbo.json → passThroughEnv array
2. .github/workflows/ci.yml → env section
3. Run local e2e/integration suites with bun run test:integration
4. Treat missing vars as a hard failure, not a skip path