gcraft

Installation

Mon, 01 Jan 0001 00:00:00 +0000

Installation#

Prerequisites#

Go 1.21 or later is required.

Via go install#

go install github.com/Mahdyaralipor/gcraft/cmd/gcraft@latest

Make sure $(go env GOPATH)/bin is on your PATH, then verify:

gcraft version

From source#

git clone https://github.com/Mahdyaralipor/gcraft.git
cd gcraft
go build -o gcraft ./cmd/gcraft

Updating#

Re-run the go install command above with @latest, or pull and rebuild from source.

Uninstalling#

rm $(go env GOPATH)/bin/gcraft

Getting Started

Mon, 01 Jan 0001 00:00:00 +0000

Getting Started#

gcraft parses a struct or interface with go/ast and writes a <type>_gen.go file next to it — no reflection, no runtime dependency on gcraft itself.

Your first generation#

// user.go
package model

type User struct {
	Name string
	Email string
	Age int
}

gcraft generate -type User -src ./user.go

This creates user_gen.go with a Builder, Validator, and Clone method, all enabled by default.

Disable specific generators#

gcraft generate -type Repository -src ./repo.go -builder=false

Custom output path#

gcraft generate -type Order -src ./models/ -out ./models/order_gen.go

All flags#

gcraft generate -type [flags] -builder generate Builder pattern (default true)

Builder

Mon, 01 Jan 0001 00:00:00 +0000

Builder#

Writing test fixtures by hand means repeating the same struct literal everywhere, and editing every call site whenever a field is added. The Builder generator gives you a fluent With...() API instead. Enabled by default; disable with -builder=false.

gcraft generate -type User -src ./user.go

type User struct {
	Name string
	Email string
	Age int
}

Generates:

type UserBuilder struct {
	v User
}

func NewUserBuilder() *UserBuilder {
	return &UserBuilder{}
}

func (b *UserBuilder) WithName(v string) *UserBuilder {
	b.v.Name = v
	return b
}

func (b *UserBuilder) WithEmail(v string) *UserBuilder {
	b.v.Email = v
	return b
}

func (b *UserBuilder) WithAge(v int) *UserBuilder {
	b.v.Age = v
	return b
}

func (b *UserBuilder) Build() User {
	return b.v
}

Usage:

Validator

Mon, 01 Jan 0001 00:00:00 +0000

Validator#

Generates a Validate() error method. Currently it checks that non-empty string fields are not left as their zero value — other types (numbers, bools, etc.) are not validated. Enabled by default; disable with -validate=false.

gcraft generate -type User -src ./user.go

type User struct {
	Name string
	Email string
	Age int
}

Generates:

func (v User) Validate() error {
	if v.Name == "" {
		return fmt.Errorf("User.Name is required")
	}
	if v.Email == "" {
		return fmt.Errorf("User.Email is required")
	}
	return nil
}

if err := user.Validate(); err != nil {
 log.Fatal(err)
}

Clone

Mon, 01 Jan 0001 00:00:00 +0000

Clone#

Generates a Clone() method. For plain value fields it’s a simple struct copy; for slice fields, gcraft generates an explicit deep copy so the clone doesn’t share the same backing array as the original. Enabled by default; disable with -clone=false.

gcraft generate -type User -src ./user.go

Generates:

func (v User) Clone() User {
	c := v
	return c
}

copy := user.Clone()
copy.Name = "Changed"
// original `user` is untouched

Mock

Mon, 01 Jan 0001 00:00:00 +0000

Mock#

Generates a mock implementation for an interface (not structs) — each method becomes a <Method>Func field plus a <Method>Called counter, so you can both stub behavior and assert call counts. Enabled by default; disable with -mock=false.

gcraft generate -type Notifier -src ./notifier.go

type Notifier interface {
	Send(to, message string) error
}

Generates:

type MockNotifier struct {
	SendFunc func(to string, message string) error
	SendCalled int
}

func (m *MockNotifier) Send(to string, message string) error {
	m.SendCalled++
	if m.SendFunc != nil {
		return m.SendFunc(to, message)
	}
	return nil
}

Usage in a test:

mock := &MockNotifier{
	SendFunc: func(to, message string) error {
		return nil
	},
}

svc.Notify(mock) // svc takes a Notifier

if mock.SendCalled != 1 {
	t.Errorf("expected Send to be called once, got %d", mock.SendCalled)
}