Test Data Management
When to use: Every test that interacts with data — user accounts, form inputs, entities, or any state that must exist before assertions run.
Quick Reference
| Strategy | Speed | Isolation | Complexity | Best For |
|---|---|---|---|---|
| Inline data | Instant | Perfect | None | Simple value checks, form inputs |
| Factory functions | Instant | Perfect | Low | Unique identifiers, consistent shapes |
| Faker/random data | Instant | Perfect | Low | Realistic fields, edge-case discovery |
| Builder pattern | Instant | Perfect | Medium | Complex objects with many optional fields |
| API seeding | Fast | Perfect | Medium | Creating entities the app depends on |
| Database seeding | Fast | Good | High | Complex relational data, bulk setup |
| Storage state | Fast | Good | Low | Reusing authenticated sessions |
| Fixture-based setup | Fast | Perfect | Medium | Encapsulating setup + guaranteed teardown |
Core principle: Every test creates its own data and cleans up after itself. No test should depend on data left behind by another test or pre-existing in the environment.
Patterns
Inline Test Data
Use when: The data is simple, unique to one test, and essential for understanding the assertion.
Avoid when: The same data shape repeats across many tests — extract a factory instead.
Inline data makes tests self-documenting. The reader sees exactly what matters without chasing imports.
TypeScript
// tests/contact-form.spec.ts
import { test, expect } from "@playwright/test"
test("submits contact form with valid data", async ({ page }) => {
const name = "Ada Lovelace"
const email = `ada-${Date.now()}@example.com`
const message = "Inquiry about analytics engine"
await page.goto("/contact")
await page.getByLabel("Name").fill(name)
await page.getByLabel("Email").fill(email)
await page.getByLabel("Message").fill(message)
await page.getByRole("button", { name: "Send" }).click()
await expect(page.getByText("Thank you, Ada Lovelace")).toBeVisible()
})JavaScript
// tests/contact-form.spec.js
const { test, expect } = require("@playwright/test")
test("submits contact form with valid data", async ({ page }) => {
const name = "Ada Lovelace"
const email = `ada-${Date.now()}@example.com`
const message = "Inquiry about analytics engine"
await page.goto("/contact")
await page.getByLabel("Name").fill(name)
await page.getByLabel("Email").fill(email)
await page.getByLabel("Message").fill(message)
await page.getByRole("button", { name: "Send" }).click()
await expect(page.getByText("Thank you, Ada Lovelace")).toBeVisible()
})Use Date.now() or crypto.randomUUID() for fields that must be unique (emails, usernames). This prevents collisions during parallel execution.
Factory Functions
Use when: Multiple tests need the same data shape with different values, or you need guaranteed uniqueness.
Avoid when: The data is trivial and only used once — inline it instead.
Factories centralize data creation logic. When the data shape changes, you update one function, not dozens of tests.
TypeScript
// tests/factories/user.factory.ts
export interface UserData {
firstName: string
lastName: string
email: string
password: string
}
let counter = 0
export function createUserData(overrides: Partial<UserData> = {}): UserData {
counter++
const id = `${Date.now()}-${counter}`
return {
firstName: `Test`,
lastName: `User${id}`,
email: `testuser-${id}@example.com`,
password: "SecureP@ss123!",
...overrides,
}
}// tests/registration.spec.ts
import { test, expect } from "@playwright/test"
import { createUserData } from "./factories/user.factory"
test("registers a new user", async ({ page }) => {
const user = createUserData()
await page.goto("/register")
await page.getByLabel("First name").fill(user.firstName)
await page.getByLabel("Last name").fill(user.lastName)
await page.getByLabel("Email").fill(user.email)
await page.getByLabel("Password").fill(user.password)
await page.getByRole("button", { name: "Create account" }).click()
await expect(page.getByText(`Welcome, ${user.firstName}`)).toBeVisible()
})
test("rejects duplicate email", async ({ page }) => {
const user = createUserData({ email: "duplicate@example.com" })
await page.goto("/register")
await page.getByLabel("Email").fill(user.email)
await page.getByLabel("Password").fill(user.password)
await page.getByRole("button", { name: "Create account" }).click()
await expect(page.getByText("Email already registered")).toBeVisible()
})JavaScript
// tests/factories/user.factory.js
let counter = 0
function createUserData(overrides = {}) {
counter++
const id = `${Date.now()}-${counter}`
return {
firstName: "Test",
lastName: `User${id}`,
email: `testuser-${id}@example.com`,
password: "SecureP@ss123!",
...overrides,
}
}
module.exports = { createUserData }// tests/registration.spec.js
const { test, expect } = require("@playwright/test")
const { createUserData } = require("./factories/user.factory")
test("registers a new user", async ({ page }) => {
const user = createUserData()
await page.goto("/register")
await page.getByLabel("First name").fill(user.firstName)
await page.getByLabel("Last name").fill(user.lastName)
await page.getByLabel("Email").fill(user.email)
await page.getByLabel("Password").fill(user.password)
await page.getByRole("button", { name: "Create account" }).click()
await expect(page.getByText(`Welcome, ${user.firstName}`)).toBeVisible()
})Faker / Random Data
Use when: You need realistic-looking data (names, addresses, phone numbers) or want to discover edge cases through randomness.
Avoid when: Debugging a failure — use a fixed seed to make it reproducible.
Always seed faker so failures are reproducible. Use testInfo.testId or a fixed seed per test file.
TypeScript
// tests/factories/faker-user.factory.ts
import { faker } from "@faker-js/faker"
export function createFakerUser(seed?: number) {
if (seed !== undefined) {
faker.seed(seed)
}
return {
firstName: faker.person.firstName(),
lastName: faker.person.lastName(),
email: faker.internet.email({ provider: "testmail.example.com" }),
phone: faker.phone.number(),
address: {
street: faker.location.streetAddress(),
city: faker.location.city(),
state: faker.location.state({ abbreviated: true }),
zip: faker.location.zipCode(),
},
}
}// tests/checkout.spec.ts
import { test, expect } from "@playwright/test"
import { createFakerUser } from "./factories/faker-user.factory"
test("completes checkout with shipping address", async ({ page }, testInfo) => {
// Seed with a stable value so re-runs produce the same data
const user = createFakerUser(testInfo.workerIndex)
await page.goto("/checkout")
await page.getByLabel("Street address").fill(user.address.street)
await page.getByLabel("City").fill(user.address.city)
await page.getByLabel("State").fill(user.address.state)
await page.getByLabel("ZIP code").fill(user.address.zip)
await page.getByRole("button", { name: "Place order" }).click()
await expect(page.getByText("Order confirmed")).toBeVisible()
})JavaScript
// tests/factories/faker-user.factory.js
const { faker } = require("@faker-js/faker")
function createFakerUser(seed) {
if (seed !== undefined) {
faker.seed(seed)
}
return {
firstName: faker.person.firstName(),
lastName: faker.person.lastName(),
email: faker.internet.email({ provider: "testmail.example.com" }),
phone: faker.phone.number(),
address: {
street: faker.location.streetAddress(),
city: faker.location.city(),
state: faker.location.state({ abbreviated: true }),
zip: faker.location.zipCode(),
},
}
}
module.exports = { createFakerUser }// tests/checkout.spec.js
const { test, expect } = require("@playwright/test")
const { createFakerUser } = require("./factories/faker-user.factory")
test("completes checkout with shipping address", async ({ page }, testInfo) => {
const user = createFakerUser(testInfo.workerIndex)
await page.goto("/checkout")
await page.getByLabel("Street address").fill(user.address.street)
await page.getByLabel("City").fill(user.address.city)
await page.getByLabel("State").fill(user.address.state)
await page.getByLabel("ZIP code").fill(user.address.zip)
await page.getByRole("button", { name: "Place order" }).click()
await expect(page.getByText("Order confirmed")).toBeVisible()
})Always use a test-specific email domain (e.g., testmail.example.com) so faker-generated emails never hit real inboxes. The example.com domain is reserved by RFC 2606 and is safe for testing.
Builder Pattern
Use when: Objects have many optional fields, conditional logic, or multiple valid configurations. Common for product listings, user profiles, or form payloads with nested data.
Avoid when: The object has fewer than 5 fields — a factory with overrides is simpler.
TypeScript
// tests/builders/product.builder.ts
export interface Product {
name: string
price: number
currency: string
category: string
description: string
inStock: boolean
tags: string[]
variants: { size: string; color: string }[]
}
export class ProductBuilder {
private product: Product = {
name: `Product-${Date.now()}`,
price: 29.99,
currency: "USD",
category: "Electronics",
description: "A test product",
inStock: true,
tags: [],
variants: [],
}
withName(name: string): this {
this.product.name = name
return this
}
withPrice(price: number, currency = "USD"): this {
this.product.price = price
this.product.currency = currency
return this
}
withCategory(category: string): this {
this.product.category = category
return this
}
outOfStock(): this {
this.product.inStock = false
return this
}
withTags(...tags: string[]): this {
this.product.tags = tags
return this
}
withVariant(size: string, color: string): this {
this.product.variants.push({ size, color })
return this
}
build(): Product {
return { ...this.product }
}
}// tests/product-catalog.spec.ts
import { test, expect } from "@playwright/test"
import { ProductBuilder } from "./builders/product.builder"
test("displays out-of-stock badge for unavailable products", async ({ page, request }) => {
const product = new ProductBuilder()
.withName("Wireless Keyboard")
.withCategory("Accessories")
.outOfStock()
.build()
// Seed via API (see API Seeding pattern below)
await request.post("/api/products", { data: product })
await page.goto("/products")
const card = page.getByRole("listitem").filter({ hasText: product.name })
await expect(card.getByText("Out of Stock")).toBeVisible()
})JavaScript
// tests/builders/product.builder.js
class ProductBuilder {
constructor() {
this.product = {
name: `Product-${Date.now()}`,
price: 29.99,
currency: "USD",
category: "Electronics",
description: "A test product",
inStock: true,
tags: [],
variants: [],
}
}
withName(name) {
this.product.name = name
return this
}
withPrice(price, currency = "USD") {
this.product.price = price
this.product.currency = currency
return this
}
withCategory(category) {
this.product.category = category
return this
}
outOfStock() {
this.product.inStock = false
return this
}
withTags(...tags) {
this.product.tags = tags
return this
}
withVariant(size, color) {
this.product.variants.push({ size, color })
return this
}
build() {
return { ...this.product }
}
}
module.exports = { ProductBuilder }// tests/product-catalog.spec.js
const { test, expect } = require("@playwright/test")
const { ProductBuilder } = require("./builders/product.builder")
test("displays out-of-stock badge for unavailable products", async ({ page, request }) => {
const product = new ProductBuilder()
.withName("Wireless Keyboard")
.withCategory("Accessories")
.outOfStock()
.build()
await request.post("/api/products", { data: product })
await page.goto("/products")
const card = page.getByRole("listitem").filter({ hasText: product.name })
await expect(card.getByText("Out of Stock")).toBeVisible()
})API Seeding
Use when: Tests need entities to already exist (users, products, orders) and the app exposes APIs to create them. This is the default strategy for test data setup.
Avoid when: No API exists for the entity, or the API itself is what you are testing (use the UI or database instead).
API seeding is faster than UI-based setup, more maintainable than database seeding, and exercises real application logic. Prefer it over all other approaches when an API is available.
TypeScript
// tests/fixtures/api-data.fixture.ts
import { test as base, APIRequestContext } from "@playwright/test"
import { createUserData, UserData } from "../factories/user.factory"
type ApiDataFixtures = {
apiUser: UserData & { id: string }
}
export const test = base.extend<ApiDataFixtures>({
apiUser: async ({ request }, use) => {
const userData = createUserData()
// Create
const response = await request.post("/api/users", { data: userData })
const created = await response.json()
const user = { ...userData, id: created.id }
// Provide to test
await use(user)
// Cleanup — runs even if test fails
await request.delete(`/api/users/${user.id}`)
},
})
export { expect } from "@playwright/test"// tests/user-profile.spec.ts
import { test, expect } from "./fixtures/api-data.fixture"
test("edits user profile name", async ({ page, apiUser }) => {
await page.goto(`/users/${apiUser.id}/profile`)
await page.getByLabel("First name").fill("Updated")
await page.getByRole("button", { name: "Save" }).click()
await expect(page.getByText("Profile updated")).toBeVisible()
})JavaScript
// tests/fixtures/api-data.fixture.js
const { test: base } = require("@playwright/test")
const { createUserData } = require("../factories/user.factory")
const test = base.extend({
apiUser: async ({ request }, use) => {
const userData = createUserData()
const response = await request.post("/api/users", { data: userData })
const created = await response.json()
const user = { ...userData, id: created.id }
await use(user)
await request.delete(`/api/users/${user.id}`)
},
})
module.exports = { test, expect: require("@playwright/test").expect }// tests/user-profile.spec.js
const { test, expect } = require("./fixtures/api-data.fixture")
test("edits user profile name", async ({ page, apiUser }) => {
await page.goto(`/users/${apiUser.id}/profile`)
await page.getByLabel("First name").fill("Updated")
await page.getByRole("button", { name: "Save" }).click()
await expect(page.getByText("Profile updated")).toBeVisible()
})For multi-entity seeding, compose fixtures:
TypeScript
// tests/fixtures/order-data.fixture.ts
import { test as base } from "./api-data.fixture"
export const test = base.extend({
apiOrder: async ({ request, apiUser }, use) => {
const orderResponse = await request.post("/api/orders", {
data: { userId: apiUser.id, items: [{ sku: "WIDGET-001", qty: 2 }] },
})
const order = await orderResponse.json()
await use(order)
await request.delete(`/api/orders/${order.id}`)
},
})Database Seeding
Use when: No API exists for the data you need, you need bulk data, or you need to set up complex relational state that is cumbersome via API calls.
Avoid when: An API exists — API seeding is more maintainable and exercises real application logic. Database seeding couples tests to schema details.
TypeScript
// tests/fixtures/db.fixture.ts
import { test as base } from "@playwright/test"
import { Pool } from "pg"
type DbFixtures = {
db: Pool
seededOrg: { id: string; name: string }
}
export const test = base.extend<DbFixtures>({
db: async ({}, use) => {
const pool = new Pool({
connectionString: process.env.TEST_DATABASE_URL,
})
await use(pool)
await pool.end()
},
seededOrg: async ({ db }, use) => {
const orgName = `TestOrg-${Date.now()}`
const result = await db.query(
"INSERT INTO organizations (name, plan) VALUES ($1, $2) RETURNING id",
[orgName, "enterprise"]
)
const orgId = result.rows[0].id
await use({ id: orgId, name: orgName })
// Cascade delete cleans up related data
await db.query("DELETE FROM organizations WHERE id = $1", [orgId])
},
})
export { expect } from "@playwright/test"JavaScript
// tests/fixtures/db.fixture.js
const { test: base } = require("@playwright/test")
const { Pool } = require("pg")
const test = base.extend({
db: async ({}, use) => {
const pool = new Pool({
connectionString: process.env.TEST_DATABASE_URL,
})
await use(pool)
await pool.end()
},
seededOrg: async ({ db }, use) => {
const orgName = `TestOrg-${Date.now()}`
const result = await db.query(
"INSERT INTO organizations (name, plan) VALUES ($1, $2) RETURNING id",
[orgName, "enterprise"]
)
const orgId = result.rows[0].id
await use({ id: orgId, name: orgName })
await db.query("DELETE FROM organizations WHERE id = $1", [orgId])
},
})
module.exports = { test, expect: require("@playwright/test").expect }Always use parameterized queries ($1, $2) to prevent SQL injection — even in tests. It is a good habit and prevents breakage from special characters in generated data.
Storage State
Use when: Multiple tests need an authenticated session and you want to avoid logging in via the UI in every test.
Avoid when: The test is specifically testing the login flow itself.
Generate storage state once in a setup project, then reuse it across all tests that need authentication.
TypeScript
// playwright.config.ts
import { defineConfig } from "@playwright/test"
export default defineConfig({
projects: [
{
name: "auth-setup",
testMatch: /auth\.setup\.ts/,
},
{
name: "authenticated-tests",
dependencies: ["auth-setup"],
use: {
storageState: ".auth/user.json",
},
},
],
})// tests/auth.setup.ts
import { test as setup, expect } from "@playwright/test"
import path from "node:path"
const authFile = path.join(__dirname, "..", ".auth", "user.json")
setup("authenticate as standard user", async ({ page }) => {
await page.goto("/login")
await page.getByLabel("Email").fill(process.env.TEST_USER_EMAIL!)
await page.getByLabel("Password").fill(process.env.TEST_USER_PASSWORD!)
await page.getByRole("button", { name: "Sign in" }).click()
await expect(page.getByRole("heading", { name: "Dashboard" })).toBeVisible()
await page.context().storageState({ path: authFile })
})JavaScript
// playwright.config.js
const { defineConfig } = require("@playwright/test")
module.exports = defineConfig({
projects: [
{
name: "auth-setup",
testMatch: /auth\.setup\.js/,
},
{
name: "authenticated-tests",
dependencies: ["auth-setup"],
use: {
storageState: ".auth/user.json",
},
},
],
})// tests/auth.setup.js
const { test: setup, expect } = require("@playwright/test")
const path = require("node:path")
const authFile = path.join(__dirname, "..", ".auth", "user.json")
setup("authenticate as standard user", async ({ page }) => {
await page.goto("/login")
await page.getByLabel("Email").fill(process.env.TEST_USER_EMAIL)
await page.getByLabel("Password").fill(process.env.TEST_USER_PASSWORD)
await page.getByRole("button", { name: "Sign in" }).click()
await expect(page.getByRole("heading", { name: "Dashboard" })).toBeVisible()
await page.context().storageState({ path: authFile })
})For multiple roles, create separate setup files and storage state files:
// tests/admin-auth.setup.ts
import { test as setup } from "@playwright/test"
import path from "node:path"
const adminAuthFile = path.join(__dirname, "..", ".auth", "admin.json")
setup("authenticate as admin", async ({ page }) => {
await page.goto("/login")
await page.getByLabel("Email").fill(process.env.ADMIN_EMAIL!)
await page.getByLabel("Password").fill(process.env.ADMIN_PASSWORD!)
await page.getByRole("button", { name: "Sign in" }).click()
await page.context().storageState({ path: adminAuthFile })
})Add .auth/ to .gitignore — storage state files contain session tokens.
Test Data Cleanup
Use when: Always. Every test that creates data must clean it up.
Avoid when: Never. Skipping cleanup causes cascading failures in subsequent runs.
Strategy 1: Fixture teardown (preferred)
Put cleanup in the fixture's teardown block. Runs even if the test throws.
// Already shown in API Seeding — the cleanup runs after `use()`
apiUser: async ({ request }, use) => {
const user = await createViaApi(request);
await use(user);
// This ALWAYS runs — even on test failure
await request.delete(`/api/users/${user.id}`);
},Strategy 2: Batch cleanup by timestamp prefix
Tag all test-created data with a recognizable prefix, then sweep it in global teardown.
TypeScript
// global-teardown.ts
import { request } from "@playwright/test"
export default async function globalTeardown() {
const context = await request.newContext({
baseURL: process.env.BASE_URL,
})
// Delete all test entities created in this run
// Assumes entities created with the "test-" prefix
const response = await context.delete("/api/test-data/cleanup", {
data: { prefix: "test-", olderThanMinutes: 60 },
})
if (!response.ok()) {
console.warn(`Cleanup returned ${response.status()}`)
}
await context.dispose()
}JavaScript
// global-teardown.js
const { request } = require("@playwright/test")
module.exports = async function globalTeardown() {
const context = await request.newContext({
baseURL: process.env.BASE_URL,
})
const response = await context.delete("/api/test-data/cleanup", {
data: { prefix: "test-", olderThanMinutes: 60 },
})
if (!response.ok()) {
console.warn(`Cleanup returned ${response.status()}`)
}
await context.dispose()
}Strategy 3: Isolated tenant per worker
Each Playwright worker gets its own tenant/organization. All data is scoped to that tenant. Teardown deletes the entire tenant.
// tests/fixtures/tenant.fixture.ts
import { test as base } from "@playwright/test"
export const test = base.extend<{}, { workerTenant: { id: string; apiKey: string } }>({
workerTenant: [
async ({ request }, use) => {
const res = await request.post("/api/tenants", {
data: { name: `test-worker-${Date.now()}` },
})
const tenant = await res.json()
await use(tenant)
await request.delete(`/api/tenants/${tenant.id}`)
},
{ scope: "worker" },
],
})Environment-Specific Data
Use when: Tests run against multiple environments (dev, staging, production-mirror) with different base URLs, credentials, or data constraints.
Avoid when: You only have one test environment.
Never hardcode environment-specific values in test files. Use .env files and playwright.config to inject them.
TypeScript
// playwright.config.ts
import { defineConfig } from "@playwright/test"
import dotenv from "dotenv"
import path from "node:path"
// Load environment-specific .env file
const envFile = process.env.TEST_ENV || "local"
dotenv.config({ path: path.resolve(__dirname, `.env.${envFile}`) })
export default defineConfig({
use: {
baseURL: process.env.BASE_URL,
},
})# .env.local
BASE_URL=http://localhost:3000
TEST_USER_EMAIL=testuser@localhost.test
TEST_USER_PASSWORD=localpassword123
# .env.staging
BASE_URL=https://staging.example.com
TEST_USER_EMAIL=e2e-bot@staging.example.com
TEST_USER_PASSWORD=staging-secret-from-vault// tests/fixtures/env-data.fixture.ts
import { test as base } from "@playwright/test"
type EnvConfig = {
testCredentials: { email: string; password: string }
}
export const test = base.extend<EnvConfig>({
testCredentials: async ({}, use) => {
const email = process.env.TEST_USER_EMAIL
const password = process.env.TEST_USER_PASSWORD
if (!email || !password) {
throw new Error("TEST_USER_EMAIL and TEST_USER_PASSWORD must be set")
}
await use({ email, password })
},
})
export { expect } from "@playwright/test"JavaScript
// playwright.config.js
const { defineConfig } = require("@playwright/test")
const dotenv = require("dotenv")
const path = require("node:path")
const envFile = process.env.TEST_ENV || "local"
dotenv.config({ path: path.resolve(__dirname, `.env.${envFile}`) })
module.exports = defineConfig({
use: {
baseURL: process.env.BASE_URL,
},
})Run against a specific environment:
TEST_ENV=staging npx playwright testFixtures for Test Data
Use when: Test data setup and teardown should be encapsulated, reusable, and guaranteed to clean up. This is the recommended pattern for all non-trivial test data.
Avoid when: The data is a simple inline value that does not require cleanup.
Fixtures are the backbone of reliable test data management in Playwright. They compose, they guarantee teardown, and they make tests declarative.
TypeScript
// tests/fixtures/index.ts
import { test as base, expect } from "@playwright/test"
import { createUserData, UserData } from "../factories/user.factory"
type TestFixtures = {
seedUser: UserData & { id: string }
seedProduct: { id: string; name: string; price: number }
}
export const test = base.extend<TestFixtures>({
seedUser: async ({ request }, use) => {
const data = createUserData()
const res = await request.post("/api/users", { data })
expect(res.ok()).toBeTruthy()
const user = { ...data, id: (await res.json()).id }
await use(user)
await request.delete(`/api/users/${user.id}`)
},
seedProduct: async ({ request }, use) => {
const data = {
name: `Product-${Date.now()}`,
price: 49.99,
category: "Testing",
}
const res = await request.post("/api/products", { data })
expect(res.ok()).toBeTruthy()
const product = { ...data, id: (await res.json()).id }
await use(product)
await request.delete(`/api/products/${product.id}`)
},
})
export { expect }// tests/shopping-cart.spec.ts
import { test, expect } from "./fixtures"
test("adds product to cart", async ({ page, seedUser, seedProduct }) => {
// seedUser and seedProduct are already created and will be cleaned up automatically
await page.goto(`/products/${seedProduct.id}`)
await page.getByRole("button", { name: "Add to cart" }).click()
await page.goto("/cart")
await expect(page.getByText(seedProduct.name)).toBeVisible()
await expect(page.getByText("$49.99")).toBeVisible()
})JavaScript
// tests/fixtures/index.js
const { test: base, expect } = require("@playwright/test")
const { createUserData } = require("../factories/user.factory")
const test = base.extend({
seedUser: async ({ request }, use) => {
const data = createUserData()
const res = await request.post("/api/users", { data })
expect(res.ok()).toBeTruthy()
const user = { ...data, id: (await res.json()).id }
await use(user)
await request.delete(`/api/users/${user.id}`)
},
seedProduct: async ({ request }, use) => {
const data = {
name: `Product-${Date.now()}`,
price: 49.99,
category: "Testing",
}
const res = await request.post("/api/products", { data })
expect(res.ok()).toBeTruthy()
const product = { ...data, id: (await res.json()).id }
await use(product)
await request.delete(`/api/products/${product.id}`)
},
})
module.exports = { test, expect }// tests/shopping-cart.spec.js
const { test, expect } = require("./fixtures")
test("adds product to cart", async ({ page, seedUser, seedProduct }) => {
await page.goto(`/products/${seedProduct.id}`)
await page.getByRole("button", { name: "Add to cart" }).click()
await page.goto("/cart")
await expect(page.getByText(seedProduct.name)).toBeVisible()
await expect(page.getByText("$49.99")).toBeVisible()
})Fixtures only run when a test requests them by name. If a test does not use seedProduct, the product is never created — no wasted setup, no unnecessary cleanup.
Decision Guide
What data does your test need?
│
├── Simple values (strings, numbers for form fields)?
│ └── Use INLINE DATA — keep it in the test
│
├── Same shape used across many tests?
│ ├── < 5 fields? → Use a FACTORY FUNCTION
│ └── >= 5 fields with optional/conditional fields? → Use a BUILDER
│
├── Need realistic-looking data (names, addresses)?
│ └── Use FAKER with a fixed seed
│
├── Entities that must exist before the test starts?
│ ├── App has an API for this entity?
│ │ └── Use API SEEDING in a fixture (preferred)
│ ├── No API, but have database access?
│ │ └── Use DATABASE SEEDING in a fixture
│ └── No API, no DB access?
│ └── Use UI setup in a beforeEach (slowest — avoid if possible)
│
├── Need an authenticated session?
│ └── Use STORAGE STATE via setup project
│
└── Need data isolated per worker?
└── Use WORKER-SCOPED FIXTURES with tenant isolationSpeed ranking (fastest to slowest)
- Inline data / factories / faker — no I/O, instant
- API seeding — one HTTP call per entity
- Database seeding — direct DB call, skips app logic
- Storage state — one-time login, reused across tests
- UI-based setup — full browser interaction per test (avoid)
Isolation ranking (most to least isolated)
- Test-scoped fixtures with API teardown — each test gets fresh data, cleaned up after
- Worker-scoped tenant isolation — tests in a worker share a tenant, cleaned up when worker exits
- Timestamp-prefixed batch cleanup — catches orphaned data, runs in global teardown
- Shared database state — fragile, prone to ordering bugs (avoid)
Anti-Patterns
Shared mutable data across tests
// BAD — tests share the same user object and depend on execution order
let sharedUser: UserData
test.beforeAll(async ({ request }) => {
sharedUser = await createUser(request)
})
test("updates user name", async ({ page }) => {
// Mutates sharedUser — other tests see the changed state
})
test("checks original name", async ({ page }) => {
// Fails because the previous test changed the name
})Fix: Use test-scoped fixtures. Each test gets its own instance.
Hardcoded IDs
// BAD — this ID only exists in your local database
test("edits product", async ({ page }) => {
await page.goto("/products/507f1f77bcf86cd799439011/edit")
})Fix: Create the product in a fixture and use the returned ID.
No cleanup
// BAD — creates data but never deletes it
test.beforeEach(async ({ request }) => {
await request.post("/api/products", { data: { name: "Leaked Product" } })
})
// Over time, the database fills with test debris causing slowdowns and false positivesFix: Always pair creation with deletion in a fixture teardown.
Relying on pre-existing database state
// BAD — assumes "Premium Plan" already exists in the database
test("subscribes to premium", async ({ page }) => {
await page.goto("/pricing")
await page.getByRole("button", { name: "Premium Plan" }).click()
// Breaks on a fresh database or different environment
})Fix: Seed the plan via API or database fixture before the test.
Using production data in tests
// BAD — tests against real customer data
test("views customer orders", async ({ page }) => {
await page.goto("/admin/customers/real-customer-id/orders")
})Fix: Create synthetic test data. Never point test suites at production databases or use real customer identifiers.
Over-engineering data setup
// BAD — abstraction for its own sake
const data = new TestDataOrchestrator()
.withStrategy("api")
.withRetry(3)
.withCleanupPolicy("deferred")
.withEnvironment("staging")
.build()Fix: A factory function and a fixture cover 95% of cases. Add complexity only when you have a proven need.
Troubleshooting
| Problem | Cause | Fix |
|---|---|---|
| Tests fail with "duplicate key" errors | Data from previous runs was not cleaned up | Add fixture teardown; run batch cleanup in globalTeardown |
| Tests pass alone but fail in parallel | Tests share mutable state or collide on unique fields | Use Date.now() or crypto.randomUUID() in factory output; use test-scoped fixtures |
| Faker produces different data on retry | Faker was not seeded, or seed changes between runs | Seed with testInfo.workerIndex or a fixed value |
| Storage state expired / session invalid | Auth tokens have a short TTL | Re-run auth setup before each suite; set fullyParallel: false on auth-dependent project if needed |
| Cleanup fails and blocks other tests | Teardown makes network calls that can timeout | Wrap cleanup in try/catch; log failures but do not throw; rely on batch cleanup as a safety net |
| Database seeding is slow | Too many individual INSERT statements | Batch inserts; use transactions; consider API seeding instead |
| Tests break when run against staging | Hardcoded values that only exist locally | Use environment variables for all environment-specific data; validate in fixture with clear error messages |
Making cleanup resilient
// Wrap fixture teardown in try/catch so a cleanup failure does not mask the real test failure
seedUser: async ({ request }, use) => {
const user = await createViaApi(request);
await use(user);
try {
await request.delete(`/api/users/${user.id}`);
} catch (error) {
console.warn(`Failed to clean up user ${user.id}:`, error);
}
},Related
- core/fixtures-and-hooks.md — fixture mechanics, scoping, composition
- core/authentication.md — storage state setup, multi-role auth patterns
- core/api-testing.md — API request context, response validation
- ci/global-setup-teardown.md — global setup/teardown for batch operations
- pom/pom-vs-fixtures-vs-helpers.md — when to use fixtures vs page objects vs helpers