faker: Instructions file for Claude Code

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Repository Overview

This is the faker library for Go - a data generation library for creating fake/mock data for testing, database seeding, and anonymization. It's heavily inspired by PHP's Faker.

The library requires Go >= 1.22 (as per go.mod) and uses Go's math/rand/v2 package for random generation.

Core Architecture

The library follows a modular design where each data type has its own file and corresponding test file:

• faker.go - Main Faker struct and GeneratorInterface that provides thread-safe random generation
• Each data category (e.g., person.go, address.go, internet.go) implements its own struct with methods
• All generators are accessed through the main Faker instance created with faker.New()
• The library uses struct tags (fake:"...") to support generating fake data directly into structs

Key pattern: Each generator returns a new instance that shares the same underlying random generator for consistency and thread safety.

Common Commands

Testing

# Run all tests
go test ./...

# Run tests with verbose output
go test -v ./...

# Run tests with benchmarks
go test -v -bench=. ./...

# Run a specific test
go test -run TestPersonName -v

# Run tests multiple times (as done in CI)
for i in 1 2 3; do go test -v -bench=. ./... && break || if [ $i -eq 3 ]; then exit 1; fi; done

Code Quality

# Format code
gofmt -w .

# Check for issues
go vet ./...

# Build the library
go build ./...

Note: There are known struct tag syntax issues in struct_test.go (lines 239, 248, 274) that cause go vet warnings. These are intentional test cases for malformed tags.

Development Workflow

1. The library is purely functional with no external dependencies beyond Go standard library
2. Each data generator should have comprehensive tests in its corresponding _test.go file
3. Thread safety is handled at the Faker struct level through the threadSafeRand wrapper
4. When adding new generators, follow the existing pattern of creating a new struct type with methods
5. The main branch is master (not main)