cckit

README

Hyperledger Fabric chaincode kit (CCKit)

CCKit is a programming toolkit for developing and testing hyperledger fabric golang chaincodes. It enhances the development experience while providing developers components for creating more readable and secure smart contracts (chaincodes).

Overview

A smart contract is code – invoked by a client application external to the blockchain network – that manages access and modifications to a set of key-value pairs in the World State. In Hyperledger Fabric, smart contracts are referred to as chaincode.

CCKit features

• Centralized chaincode invocation handling with methods routing and middleware capabilities
• Chaincode state modelling using protocol buffers / json marshalling
• MockStub testing, allowing to immediately receive test results
• Data encryption on application level
• Chaincode method access control

Problems with existing chaincode examples

There are several chaincode examples available:

• Commercial paper from official Hyperledger Fabric documentation
• Blockchain insurance application ( testing tutorial: how to write tests for "insurance" chaincode )
• Marbles from hyperledger
• Marbles from IBM-Blockchain

Main problems:

• Chaincode methods routing appeared only in HLF 1.4 and only in Node.Js chaincode
• Lots of code duplication (json marshalling / unmarshalling, validation, access control etc)
• Uncompleted testing tools (MockStub)

Publications

• Hyperledger Fabric smart contract data model: protobuf to chaincode state mapping
• ERC20 token as Hyperledger Fabric Golang chaincode
• CCKit: Routing and middleware for Hyperledger Fabric Golang chaincode
• Developing and testing Hyperledger Fabric smart contracts [RUS]

Example based on CCKit

Chaincode "Cars"

Car registration chaincode use simple golang structure with json marshalling. Example with protobuf model is here.

source code, tests

// Simple CRUD chaincode for store information about cars
package main

import (
	"errors"
	"time"

	"github.com/s7techlab/cckit/extensions/owner"
	"github.com/s7techlab/cckit/router"
	p "github.com/s7techlab/cckit/router/param"
)

var (
	ErrCarAlreadyExists = errors.New(`car already exists`)
)

const CarEntity = `CAR`
const CarRegisteredEvent = `CAR_REGISTERED`

// CarPayload chaincode method argument
type CarPayload struct {
	Id    string
	Title string
	Owner string
}

// Car struct for chaincode state
type Car struct {
	Id    string
	Title string
	Owner string

	UpdatedAt time.Time // set by chaincode method
}

// Key for car entry in chaincode state
func (c Car) Key() ([]string, error) {
	return []string{CarEntity, c.Id}, nil
}

func New() *router.Chaincode {
	r := router.New(`cars`) // also initialized logger with "cars" prefix

	r.Init(invokeInit)

	r.Group(`car`).
		// everyone  can view information about registered cars.
		Query(`List`, queryCars).                                             // chain code method name is carList
		Query(`Get`, queryCar, p.String(`id`)).                               // chain code method name is carGet, method has 1 string argument "id"
		
		Invoke(`Register`, invokeCarRegister, p.Struct(`car`, &CarPayload{}), // 1 struct argument
			owner.Only) // allow access to method only for chaincode owner (authority)
			            // Only authority can register car information

	return router.NewChaincode(r)
}

// ======= Init ==================
func invokeInit(c router.Context) (interface{}, error) {
	return owner.SetFromCreator(c)
}

// ======= Chaincode methods =====

// car get info chaincode method handler
func queryCar(c router.Context) (interface{}, error) {
	// get state entry by composite key using CarKeyPrefix and car.Id
	//  and unmarshal from []byte to Car struct
	return c.State().Get(&Car{Id: c.ParamString(`id`)})
}

// cars car list chaincode method handler
func queryCars(c router.Context) (interface{}, error) {
	return c.State().List(
		CarEntity, // get list of state entries of type CarKeyPrefix
		&Car{})    // unmarshal from []byte and append to []Car slice
}

// carRegister car register chaincode method handler
func invokeCarRegister(c router.Context) (interface{}, error) {
	// arg name defined in router method definition
	p := c.Param(`car`).(CarPayload)

	t, _ := c.Time() // tx time
	car := &Car{     // data for chaincode state
		Id:        p.Id,
		Title:     p.Title,
		Owner:     p.Owner,
		UpdatedAt: t,
	}

	// trigger event
	c.Event().Set(CarRegisteredEvent, car)

	return car, // peer.Response payload will be json serialized car data
		//put json serialized data to state
		// create composite key using CarKeyPrefix and car.Id
		c.State().Insert(car)
}

Test for chaincode

Tests are based on a modified MockStub

package main

import (
	"testing"

	. "github.com/onsi/ginkgo"
	. "github.com/onsi/gomega"
	examplecert "github.com/s7techlab/cckit/examples/cert"
	"github.com/s7techlab/cckit/extensions/owner"
	testcc "github.com/s7techlab/cckit/testing"
	expectcc "github.com/s7techlab/cckit/testing/expect"
)

func TestCars(t *testing.T) {
	RegisterFailHandler(Fail)
	RunSpecs(t, "Cars Suite")
}

var _ = Describe(`Cars`, func() {

	//Create chaincode mock
	cc := testcc.NewMockStub(`cars`, New())

	// load actor certificates
	actors, err := examplecert.Actors(map[string]string{
		`authority`: `s7techlab.pem`,
		`someone`:   `victor-nosov.pem`,
	})
	if err != nil {
		panic(err)
	}

	// cars fixtures
	car1 := &Car{
		Id:    `A777MP77`,
		Title: `BMW`,
		Owner: `victor-nosov`,
	}

	car2 := &Car{
		Id:    `O888OO77`,
		Title: `TOYOTA`,
		Owner: `alexander`,
	}

	BeforeSuite(func() {
		// init chaincode
		expectcc.ResponseOk(cc.From(actors[`authority`]).Init()) // init chaincode from authority
	})

	Describe("Car", func() {

		It("Allow authority to add information about car", func() {
			//invoke chaincode method from authority actor
			expectcc.ResponseOk(cc.From(actors[`authority`]).Invoke(`carRegister`, car1))
		})

		It("Disallow non authority to add information about car", func() {
			//invoke chaincode method from non authority actor
			expectcc.ResponseError(
				cc.From(actors[`someone`]).Invoke(`carRegister`, car1),
				owner.ErrOwnerOnly) // expect "only owner" error
		})

		It("Disallow authority to add duplicate information about car", func() {
			expectcc.ResponseError(
				cc.From(actors[`authority`]).Invoke(`carRegister`, car1),
				ErrCarAlreadyExists) //expect already exists
		})

		It("Allow everyone to retrieve car information", func() {
			car := expectcc.PayloadIs(cc.Invoke(`carGet`, car1.Id),
				&Car{}).(Car)

			Expect(car.Title).To(Equal(car1.Title))
			Expect(car.Id).To(Equal(car1.Id))
		})

		It("Allow everyone to get car list", func() {
			//  &[]Car{} - declares target type for unmarshalling from []byte received from chaincode
			cars := expectcc.PayloadIs(cc.Invoke(`carList`), &[]Car{}).([]Car)

			Expect(len(cars)).To(Equal(1))
			Expect(cars[0].Id).To(Equal(car1.Id))
		})

		It("Allow authority to add more information about car", func() {
			// register second car
			expectcc.ResponseOk(cc.Invoke(`carRegister`, car2))
			cars := expectcc.PayloadIs(
				cc.From(actors[`authority`]).Invoke(`carList`),
				&[]Car{}).([]Car)

			Expect(len(cars)).To(Equal(2))
		})
	})
})