test-data-generation

SKILL.md

Test Data Generation

Table of Contents

Overview

When to Use

Quick Start

Reference Guides

Best Practices

Overview

Test data generation creates realistic, consistent, and maintainable test data for automated testing. Well-designed test data reduces test brittleness, improves readability, and makes it easier to create diverse test scenarios.

When to Use

Creating fixtures for integration tests

Generating fake data for development databases

Building test data with complex relationships

Creating realistic user inputs for testing

Seeding test databases

Generating edge cases and boundary values

Building reusable test data factories

Quick Start

Minimal working example:

// tests/factories/userFactory.js
const { faker } = require("@faker-js/faker");

class UserFactory {
  static build(overrides = {}) {
    return {
      id: faker.string.uuid(),
      email: faker.internet.email(),
      firstName: faker.person.firstName(),
      lastName: faker.person.lastName(),
      age: faker.number.int({ min: 18, max: 80 }),
      phone: faker.phone.number(),
      address: {
        street: faker.location.streetAddress(),
        city: faker.location.city(),
        state: faker.location.state(),
        zip: faker.location.zipCode(),
        country: "USA",
      },
      role: "user",
      isActive: true,
      createdAt: faker.date.past(),
      ...overrides,
    };
  }
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the references/ directory:

Guide
Contents

Factory Pattern for Test Data
Factory Pattern for Test Data

Builder Pattern for Complex Objects
Builder Pattern for Complex Objects

Fixtures for Integration Tests
Fixtures for Integration Tests

Realistic Data Generation
Realistic Data Generation

Best Practices

✅ DO

Use faker libraries for realistic data

Create reusable factories for common objects

Make factories flexible with overrides

Generate unique values where needed (emails, IDs)

Use builders for complex object construction

Create fixtures for integration test setup

Generate edge cases (empty strings, nulls, boundaries)

Keep test data deterministic when possible

❌ DON'T

Hardcode test data in multiple places

Use production data in tests

Generate truly random data for reproducible tests

Create overly complex factory hierarchies

Ignore data relationships and constraints

Generate massive datasets for simple tests

Forget to clean up generated data

Use the same test data for all tests

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