Agent skill

api-response-mocker

Generate realistic mock API responses with fake data. Use for testing, prototyping, or creating sample data for frontend development.

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Install this agent skill to your Project

npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/testing/api-response-mocker-dkyazzentwatwa-chatgpt-skills

SKILL.md

API Response Mocker

Generate realistic mock API responses with fake data using Faker.

Features

  • Schema-Based Generation: Define response structure
  • Faker Integration: Realistic fake data
  • Nested Objects: Complex nested structures
  • Arrays: Generate lists of objects
  • Relationships: Reference other mock data
  • Multiple Formats: JSON, XML output

Quick Start

python
from api_mocker import APIMocker

mocker = APIMocker()

# Generate user response
user = mocker.generate({
    "id": "uuid",
    "name": "name",
    "email": "email",
    "created_at": "datetime"
})

# Generate list of users
users = mocker.generate_list({
    "id": "uuid",
    "name": "name",
    "email": "email"
}, count=10)

CLI Usage

bash
# Generate from schema file
python api_mocker.py --schema user_schema.json --output user.json

# Generate list
python api_mocker.py --schema product.json --count 50 --output products.json

# Generate with seed (reproducible)
python api_mocker.py --schema order.json --seed 42 --output order.json

# Preview without saving
python api_mocker.py --schema customer.json --preview

Schema Format

Define fields using Faker provider names:

json
{
    "id": "uuid",
    "first_name": "first_name",
    "last_name": "last_name",
    "email": "email",
    "phone": "phone_number",
    "company": "company",
    "address": {
        "street": "street_address",
        "city": "city",
        "state": "state",
        "zip": "zipcode",
        "country": "country"
    },
    "created_at": "date_time_this_year",
    "is_active": "boolean"
}

Available Data Types

Personal

  • name, first_name, last_name
  • email, safe_email
  • phone_number
  • ssn

Address

  • address, street_address
  • city, state, state_abbr
  • zipcode, postcode
  • country, country_code
  • latitude, longitude

Internet

  • url, domain_name
  • ipv4, ipv6
  • user_name, password
  • uuid, uuid4
  • mac_address

Business

  • company, company_suffix
  • job, job_title
  • bs, catch_phrase

Financial

  • credit_card_number
  • iban, bban
  • currency_code
  • price (custom: returns float)

Date/Time

  • date, time
  • date_time, date_time_this_year
  • date_of_birth
  • iso8601

Text

  • text, sentence, paragraph
  • word, words
  • slug

Numeric

  • random_int, random_number
  • random_float (use {"type": "float", "min": 0, "max": 100})
  • boolean

Advanced Schemas

Arrays

json
{
    "id": "uuid",
    "name": "name",
    "tags": {
        "_array": true,
        "_count": 3,
        "_item": "word"
    },
    "orders": {
        "_array": true,
        "_count": 5,
        "_item": {
            "order_id": "uuid",
            "amount": "random_int",
            "date": "date"
        }
    }
}

Custom Values

json
{
    "id": "uuid",
    "status": {
        "_choice": ["pending", "active", "completed"]
    },
    "priority": {
        "_range": [1, 5]
    },
    "score": {
        "_float": {"min": 0.0, "max": 100.0, "decimals": 2}
    }
}

Nested Objects

json
{
    "user": {
        "id": "uuid",
        "profile": {
            "bio": "paragraph",
            "avatar_url": "image_url",
            "social": {
                "twitter": "user_name",
                "linkedin": "url"
            }
        }
    }
}

API Reference

APIMocker Class

python
class APIMocker:
    def __init__(self, locale: str = "en_US", seed: int = None)

    # Generation
    def generate(self, schema: dict) -> dict
    def generate_list(self, schema: dict, count: int = 10) -> list

    # File operations
    def from_schema_file(self, filepath: str) -> dict
    def save(self, data: any, filepath: str, format: str = "json")

    # Utilities
    def set_seed(self, seed: int)
    def get_faker(self) -> Faker

Example Schemas

User Response

json
{
    "id": "uuid",
    "username": "user_name",
    "email": "email",
    "profile": {
        "first_name": "first_name",
        "last_name": "last_name",
        "avatar": "image_url",
        "bio": "sentence"
    },
    "created_at": "iso8601",
    "last_login": "date_time_this_month"
}

E-commerce Product

json
{
    "sku": "uuid",
    "name": "catch_phrase",
    "description": "paragraph",
    "price": {"_float": {"min": 9.99, "max": 999.99}},
    "currency": "currency_code",
    "category": {"_choice": ["Electronics", "Clothing", "Home", "Sports"]},
    "in_stock": "boolean",
    "rating": {"_float": {"min": 1, "max": 5, "decimals": 1}},
    "reviews_count": {"_range": [0, 500]}
}

API Error Response

json
{
    "error": {
        "code": {"_choice": ["NOT_FOUND", "UNAUTHORIZED", "BAD_REQUEST"]},
        "message": "sentence",
        "request_id": "uuid",
        "timestamp": "iso8601"
    }
}

Dependencies

  • faker>=22.0.0

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