bun run test              # All tests with isolated Neon branch
bun run test:playwright   # Browser tests only
bun run test:integration  # Integration tests only
bun run test:unit         # Unit tests only

src/
├── lib/
│   ├── common/
│   │   ├── assert.ts
│   │   └── assert.test.ts      # Unit test (co-located)
│   └── config/
│       ├── schema.ts
│       └── schema.test.ts      # Unit test (co-located)
tests/
├── integration/
│   ├── llms.test.ts            # Integration test
│   ├── r.test.ts
│   ├── mcp/
│   │   └── route.test.ts
│   └── recipes/
│       └── [slug]/
│           └── route.test.ts
└── playwright/
    ├── auth.spec.ts            # Playwright test
    ├── chat.spec.ts
    ├── home.spec.ts
    └── lib/
        └── test-user.ts        # Playwright-specific helpers

import { test, expect } from "@playwright/test";

test.describe("Feature Name", () => {
  test("should do expected behavior", async ({ page }) => {
    await page.goto("/feature");
    // Test implementation
  });
});

import { describe, it, expect } from "bun:test";
import { GET } from "@/app/api/feature/route";

describe("GET /api/feature", () => {
  it("should return expected response", async () => {
    const response = await GET();

    expect(response.status).toBe(200);
    const data = await response.json();
    expect(data.value).toBeDefined();
  });
});

import { describe, it, expect } from "bun:test";
import { myFunction } from "./my-file";

describe("myFunction", () => {
  it("should do expected behavior", () => {
    expect(myFunction()).toBe("expected");
  });
});

// auth.spec.ts - uses auth-specific test user
const testUser = await createTestUser({
  email: `auth-test-${uuid}@example.com`,
});

// chat.spec.ts - uses chat-specific test user
const testUser = await createTestUser({
  email: `chat-test-${uuid}@example.com`,
});

test("should redirect unauthenticated user", async ({ page }) => {
  await page.goto("/protected-page");
  await expect(page).toHaveURL(/sign-in/);
});

test("should show error for invalid input", async ({ page }) => {
  await page.goto("/form");
  await page.getByRole("button", { name: /submit/i }).click();

  await expect(page.getByText(/error|required/i)).toBeVisible({
    timeout: 5000,
  });
});

import { GET } from "@/app/api/endpoint/route";

it("should return 200 for valid request", async () => {
  const response = await GET();
  expect(response.status).toBe(200);
});

bunx playwright test --headed              # Watch browser
bunx playwright test --debug               # Step through test
bunx playwright show-report                # View HTML report

bun test --only "test name"                # Run single test
bun test --watch                           # Re-run on changes