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CLAUDE.md

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

Project Overview

gotests is a Go commandline tool that automatically generates table-driven tests based on function and method signatures. It parses Go source files and generates test files with proper test scaffolding, including automatic import resolution.

Build and Test Commands

# Install the tool
go get -u github.com/cweill/gotests/...

# Build the binary
go build -o gotests ./gotests

# Run all tests
go test -v ./...

# Run tests for a specific package
go test -v ./gotests/process

# Run tests with coverage (excluding certain packages)
export PKGS=$(go list ./... | grep -vE "(gotests/gotests|.*data|templates)" | tr -s '\n' ',' | sed 's/.{1}$//')
go test -v -covermode=count -coverpkg=$PKGS -coverprofile=coverage.cov

# Run a single test
go test -v -run TestSpecificTest ./path/to/package

Note: Tests may fail when run with the -race flag (see comments in codebase).

Architecture

Core Flow

  1. Input Processing (internal/input): Resolves file paths from command-line arguments
  2. Parsing (internal/goparser): Parses Go source files into AST and extracts function signatures
  3. Model Generation (internal/models): Converts parsed data into domain models (Function, Receiver, Field, etc.)
  4. Template Rendering (internal/render): Uses Go templates to generate test code
  5. Output Generation (internal/output): Combines templates with parsed data and manages imports

Key Components

gotests.go: Main library entry point

  • GenerateTests(): Orchestrates the entire test generation pipeline
  • parallelize(): Generates tests for multiple files concurrently using goroutines
  • testableFuncs(): Filters functions based on options (exported, regex patterns, existing tests)

internal/models/models.go: Core data structures

  • Function: Represents a function/method with parameters, results, and receiver
  • Receiver: Represents method receivers with their fields
  • Field: Represents function parameters, results, or receiver fields
  • Expression: Type information including whether it's a pointer, variadic, or writer

internal/goparser/goparser.go: AST parsing

  • Parses source files into ast.File objects
  • Uses go/types package for type checking and resolution
  • Extracts function signatures, receivers, parameters, and return types

internal/render/render.go: Template system

  • Default templates in internal/render/templates/
  • Custom templates supported via -template (named sets like "testify") or -template_dir (custom directory)
  • Templates can be embedded as bindata or loaded from filesystem
  • Template functions: Field, Receiver, Param, Want, Got for generating variable names

gotests/process/process.go: Command-line processing

  • Handles file I/O and error reporting
  • Converts CLI options to library options
  • Manages writing output to stdout or files with -w flag

Template System

The tool uses Go text templates to generate test code. There are two built-in template sets:

  • test: Default table-driven tests
  • testify: Tests using the testify assertion library

Templates can be customized via:

  • -template_dir: Directory with custom templates (takes precedence)
  • -template: Named template set from templates/ directory
  • Environment variables: GOTESTS_TEMPLATE_DIR, GOTESTS_TEMPLATE

Function Filtering

Functions are filtered in this precedence order:

  1. -excl: Exclude functions matching regex (highest precedence)
  2. -exported: Only exported functions
  3. -only: Only functions matching regex
  4. -all: All functions (default is none)

Existing test functions are automatically excluded to avoid duplication.

Development Notes

  • The project uses Go modules (go.mod)
  • Minimum supported Go version: 1.6
  • The codebase uses concurrent test generation via goroutines for performance
  • Tests are in testdata/ directories with golden file comparisons in testdata/goldens/
  • The templates/ directory contains built-in template sets
  • Bindata is used to embed templates in the binary (via internal/render/bindata/)
  • Always use scripts/regenerate-goldens.sh to generate the goldens for tests.