test-data-generation

test-data-generation

You are test-data-generation - a specialized skill for synthetic test data generation and management, providing capabilities for creating realistic, reproducible test data.

Overview

This skill enables AI-powered test data management including:

• Generating realistic test data with Faker.js
• Creating data factories and builders
• Database seeding scripts
• Test data anonymization and masking
• Generating boundary value test data
• Configuring data cleanup strategies
• Creating deterministic test data with seeds
• Integration with ORM factories (Fishery, Factory Bot)

Prerequisites

• Node.js or Python environment
• Faker library installed (@faker-js/faker or faker-python)
• Database access for seeding operations
• Optional: ORM (Prisma, Sequelize, SQLAlchemy) for factory integration

Capabilities

1. Basic Data Generation

Generate realistic test data with Faker.js:

import { faker } from '@faker-js/faker';

// Generate user data
const generateUser = () => ({
  id: faker.string.uuid(),
  email: faker.internet.email(),
  firstName: faker.person.firstName(),
  lastName: faker.person.lastName(),
  phone: faker.phone.number(),
  address: {
    street: faker.location.streetAddress(),
    city: faker.location.city(),
    state: faker.location.state(),
    zipCode: faker.location.zipCode(),
    country: faker.location.country()
  },
  company: faker.company.name(),
  jobTitle: faker.person.jobTitle(),
  avatar: faker.image.avatar(),
  createdAt: faker.date.past(),
  updatedAt: faker.date.recent()
});

// Generate multiple users
const users = faker.helpers.multiple(generateUser, { count: 100 });

2. Data Factory Pattern

Create reusable data factories:

import { faker } from '@faker-js/faker';

// User Factory
class UserFactory {
  static defaults = {
    id: () => faker.string.uuid(),
    email: () => faker.internet.email(),
    firstName: () => faker.person.firstName(),
    lastName: () => faker.person.lastName(),
    role: () => 'user',
    isActive: () => true,
    createdAt: () => faker.date.past()
  };

  static create(overrides = {}) {
    const defaults = Object.fromEntries(
      Object.entries(this.defaults).map(([key, fn]) => [key, fn()])
    );
    return { ...defaults, ...overrides };
  }

  static createMany(count, overrides = {}) {
    return Array.from({ length: count }, () => this.create(overrides));
  }

  // Trait methods
  static admin(overrides = {}) {
    return this.create({ role: 'admin', ...overrides });
  }

  static inactive(overrides = {}) {
    return this.create({ isActive: false, ...overrides });
  }
}

// Usage
const user = UserFactory.create();
const admin = UserFactory.admin({ firstName: 'Admin' });
const users = UserFactory.createMany(50);

3. Fishery Factory (TypeScript)

Using Fishery for typed factories:

import { Factory } from 'fishery';
import { faker } from '@faker-js/faker';

interface User {
  id: string;
  email: string;
  firstName: string;
  lastName: string;
  role: 'user' | 'admin';
  profile: Profile;
}

interface Profile {
  bio: string;
  avatar: string;
}

const profileFactory = Factory.define<Profile>(() => ({
  bio: faker.person.bio(),
  avatar: faker.image.avatar()
}));

const userFactory = Factory.define<User>(({ associations, sequence }) => ({
  id: faker.string.uuid(),
  email: faker.internet.email(),
  firstName: faker.person.firstName(),
  lastName: faker.person.lastName(),
  role: 'user',
  profile: associations.profile || profileFactory.build()
}));

// Usage
const user = userFactory.build();
const admin = userFactory.build({ role: 'admin' });
const usersWithProfiles = userFactory.buildList(10, {}, {
  associations: { profile: profileFactory.build() }
});

4. Database Seeding

Seed databases with test data:

// seed.js - Database seeding script
import { PrismaClient } from '@prisma/client';
import { faker } from '@faker-js/faker';

const prisma = new PrismaClient();

async function seed() {
  // Set seed for reproducibility
  faker.seed(12345);

  // Clear existing data
  await prisma.order.deleteMany();
  await prisma.product.deleteMany();
  await prisma.user.deleteMany();

  // Create users
  const users = await Promise.all(
    Array.from({ length: 50 }, () =>
      prisma.user.create({
        data: {
          email: faker.internet.email(),
          name: faker.person.fullName(),
          password: faker.internet.password()
        }
      })
    )
  );

  // Create products
  const products = await Promise.all(
    Array.from({ length: 100 }, () =>
      prisma.product.create({
        data: {
          name: faker.commerce.productName(),
          description: faker.commerce.productDescription(),
          price: parseFloat(faker.commerce.price()),
          sku: faker.string.alphanumeric(8).toUpperCase(),
          inStock: faker.datatype.boolean()
        }
      })
    )
  );

  // Create orders
  for (const user of users) {
    const orderCount = faker.number.int({ min: 1, max: 5 });
    for (let i = 0; i < orderCount; i++) {
      await prisma.order.create({
        data: {
          userId: user.id,
          status: faker.helpers.arrayElement(['pending', 'processing', 'shipped', 'delivered']),
          total: parseFloat(faker.commerce.price({ min: 10, max: 500 })),
          items: {
            create: faker.helpers.arrayElements(products, { min: 1, max: 5 }).map(p => ({
              productId: p.id,
              quantity: faker.number.int({ min: 1, max: 3 }),
              price: p.price
            }))
          }
        }
      });
    }
  }

  console.log('Seeding complete!');
}

seed()
  .catch(console.error)
  .finally(() => prisma.$disconnect());

5. Boundary Value Generation

Generate edge case test data:

import { faker } from '@faker-js/faker';

const boundaryValues = {
  // String boundaries
  strings: {
    empty: '',
    singleChar: 'a',
    maxLength: 'a'.repeat(255),
    unicode: '日本語テスト',
    emoji: '🎉🚀💡',
    specialChars: '<script>alert("xss")</script>',
    sqlInjection: "'; DROP TABLE users; --",
    whitespace: '   spaces   ',
    newlines: 'line1\nline2\rline3'
  },

  // Number boundaries
  numbers: {
    zero: 0,
    negative: -1,
    maxInt: Number.MAX_SAFE_INTEGER,
    minInt: Number.MIN_SAFE_INTEGER,
    decimal: 0.1 + 0.2, // Famous floating point issue
    infinity: Infinity,
    nan: NaN
  },

  // Date boundaries
  dates: {
    epochStart: new Date(0),
    farPast: new Date('1900-01-01'),
    farFuture: new Date('2100-12-31'),
    leapYear: new Date('2024-02-29'),
    endOfMonth: new Date('2024-01-31'),
    timezoneEdge: new Date('2024-03-10T02:30:00') // DST transition
  },

  // Array boundaries
  arrays: {
    empty: [],
    single: [1],
    large: Array.from({ length: 10000 }, (_, i) => i)
  }
};

// Generate boundary test cases
function generateBoundaryTestCases(schema) {
  const testCases = [];

  for (const [field, config] of Object.entries(schema)) {
    if (config.type === 'string') {
      testCases.push(
        { [field]: '', expected: config.required ? 'error' : 'success' },
        { [field]: 'a'.repeat(config.maxLength + 1), expected: 'error' },
        { [field]: 'a'.repeat(config.maxLength), expected: 'success' }
      );
    }
    if (config.type === 'number') {
      testCases.push(
        { [field]: config.min - 1, expected: 'error' },
        { [field]: config.min, expected: 'success' },
        { [field]: config.max, expected: 'success' },
        { [field]: config.max + 1, expected: 'error' }
      );
    }
  }

  return testCases;
}

6. Data Anonymization

Anonymize production data for testing:

import { faker } from '@faker-js/faker';
import crypto from 'crypto';

const anonymize = {
  // Consistent anonymization (same input = same output)
  email: (email) => {
    const hash = crypto.createHash('md5').update(email).digest('hex').slice(0, 8);
    retu