rendertrust: Skill for Claude Code

Testing Patterns Skill

Purpose

Guide consistent and effective testing. Routes to existing test patterns and provides evidence templates for Linear.

When This Skill Applies

Invoke this skill when:

• Writing new unit tests
• Creating integration tests
• Setting up test fixtures with RLS
• Running test suites
• Packaging test evidence for Linear

Critical Rules

❌ FORBIDDEN Patterns

// FORBIDDEN: Direct Prisma calls in tests (bypass RLS)
const user = await prisma.user.findUnique({ where: { user_id } });

// FORBIDDEN: Shared test state (causes flaky tests)
let sharedUser: User;
beforeAll(() => { sharedUser = createUser(); });

// FORBIDDEN: Hard-coded IDs (test pollution)
const userId = "user-123";

// FORBIDDEN: Missing cleanup (leaky tests)
it("creates user", async () => {
  await prisma.user.create({ data: userData });
  // No cleanup!
});

✅ CORRECT Patterns

// CORRECT: Use RLS context helpers
const user = await withSystemContext(prisma, "test", async (client) => {
  return client.user.findUnique({ where: { user_id } });
});

// CORRECT: Isolated test state per test
beforeEach(() => {
  const testUser = createTestUser();
});

// CORRECT: Unique identifiers
const userId = `user-${crypto.randomUUID()}`;
const email = `test-${Date.now()}@example.com`;

// CORRECT: Proper cleanup
afterEach(async () => {
  await withSystemContext(prisma, "test", async (client) => {
    await client.user.deleteMany({ where: { email: { contains: "test-" } } });
  });
});

Test Directory Structure

__tests__/
├── unit/              # Fast, isolated tests
│   ├── components/    # React component tests
│   ├── lib/           # Library function tests
│   ├── services/      # Service layer tests
│   └── user/          # User helper tests
├── integration/       # API and database tests
├── database/          # Database helper tests
├── e2e/               # End-to-end tests (Playwright)
├── payments/          # Payment flow tests
└── setup.ts           # Global test setup