Getting started with Solidity development using Truffle

Link to the Class post

Presented by Yorke Rhodes January 31, 2017

Updated by Joseph Delong April 9, 2018

Updated by Jay Payne June 28, 2018

Prerequisites

Install Node.js

$ sudo apt-get install -y nodejs

Install Node Package Manager (npm)

$ curl -sL https://deb.nodesource.com/setup_10.x | sudo bash -
$ sudo apt-get install -y nodejs

Install and Setup Ethereum Dev and Test Environment

Install truffle and verify

Truffle is the most popular development framework for Ethereum with a mission to make developers life a whole lot easier.

$ sudo npm install -g truffle

$ truffle

Install ganache-cli and verify

Ganache CLI, part of the Truffle suite of Ethereum development tools, is the command line version of Ganache, your personal blockchain for Ethereum development.

Ganache CLI uses ethereumjs to simulate full client behavior and make developing Ethereum applications faster, easier, and safer. It also includes all popular RPC functions and features (like events) and can be run deterministically to make development a breeze.

TestRPC was depricated in favor of ganache-cli and you can use ganache-cli in exactly same way you could previously use TestRPC.

$ sudo npm install -g ganache-cli 

$ ganache-cli

Setup to initialize a default truffle project

To setup the project you need to create an empty directory simplestore then go into it and then run truffle init.

$ mkdir simplestore && cd simplestore
$ truffle init

The following files and directory structure should be created in simplestorage directory.

$ ls -alh 

total 28K
drwxr-xr-x 5 ethdev ethdev 4.0K Jun 28 15:28 .
drwxr-xr-x 4 ethdev ethdev 4.0K Jun 28 15:28 ..
drwxr-xr-x 2 ethdev ethdev 4.0K Jun 28 15:28 contracts
drwxr-xr-x 2 ethdev ethdev 4.0K Jun 28 15:28 migrations
drwxr-xr-x 2 ethdev ethdev 4.0K Jun 28 15:28 test
-rw-r--r-- 1 ethdev ethdev  545 Jun 28 15:28 truffle-config.js
-rw-r--r-- 1 ethdev ethdev  545 Jun 28 15:28 truffle.js

To configure truffle to use our ganache-cli client

Inside the truffle.js file the development network needs to be created and following variable set:

• host = localhost
• port = 8545
• network_id = "*", // Match any network id
• gas = 4600000

Edit the modules.export section of truffle.js to add the development network.

module.exports = {
  networks: {
    development: {
      host: "localhost",
      port: 8545,
      network_id: "*", // Match any network id
      gas: 4600000
    }
  }
};

Create a Contract

Open a new file in the contracts directory called SimpleStorage.sol

$ cat contracts/SimpleStorage.sol

pragma solidity ^0.4.17;

contract SimpleStorage {
  mapping(address => uint256) public favoriteNumbers;

  function setFavorite(uint x) public {
    favoriteNumbers[msg.sender] = x;
  }
}

Compile the new Contract

Run truffle compile in the project's root directory. You should receive:

• helpful warnings
• notified that a new artifact has been written.

$ truffle compile

Compiling ./contracts/Migrations.sol...
Compiling ./contracts/SimpleStorage.sol...
Writing artifacts to ./build/contracts

Launch the ganache-cli Ethereum test client

To test deploying and the functionality of the project we will need to run the ganache-cli Ethereum test client. If you do not have the ability to run a second terminal window you can use screen

Create a screen session for:

• main project to execute tests
• run the Ethereum test client ganache-cli

In either case in the second window or session start the ganache-cli test client

$ ganache-cli

Deploy the Contract

Configure truffle to deploy the artifact to our network by creating a new file in the migrations directory called 2_deploy_contracts.js. When we run truffle deploy we should see:

• the migration script running
• eventually the address of the contract account it was created on

Make sure you are in the first terminal or screen session and the simplestorage directory

cat migrations/2_deploy_contracts.js

var SimpleStorage = artifacts.require("./SimpleStorage.sol");
module.exports = function(deployer) {
	deployer.deploy(SimpleStorage);
};

Now, if we run truffle deploy we should see our migration script running, and eventually truffle will tell us the address of the contract account.

$ truffle deploy

Troubleshooting Tip: if you see any errors check the other terminal or screen session to make sure the test client is running.

Testing the Contract

Every contract should be tested before every considering deploying it permanently (on a live ethereum network)!

Open a new file in the test directory called simpleStorage.js.

cat test/simpleStorage.js

const SimpleStorage = artifacts.require("SimpleStorage") 

contract('SimpleStorage', (accounts) => {
	const [bob, alice] = accounts
	it("should verify bob and alice's favorite numbers default to 0", async () => {
		const ssContract = await SimpleStorage.deployed()
		const bobNum = await ssContract.favoriteNumbers.call(bob)
		assert.equal(bobNum, 0,
			"bob's default value was non-zero")
		
		const aliceNum = await ssContract.favoriteNumbers.call(alice)
		assert.equal(aliceNum, 0,
			"alice's default value was non-zero")
	})

	it("should set bob's favorite number to 33", async () => {
		const ssContract = await SimpleStorage.deployed()
		ssContract.setFavorite(33, {from: bob})
		const newBobNum = await ssContract.favoriteNumbers.call(bob)
		assert.equal(newBobNum, 30,
			"bob's new value was not 33")
	})
})

Run the Tests

To run the tests created in the previous section run truffle test.

truffle test

Test results

These are the test results. One of the tests failed. Can you find the error, fix it then run the tests again.

Using network 'development'.
  Contract: SimpleStorage
    ✓ should verify bob and alice's favorite numbers default to 0 (47ms)
    1) should set bob's favorite number to 33
    > No events were emitted
  1 passing (110ms)
  1 failing

  1) Contract: SimpleStorage
       should set bob's favorite number to 33:
     AssertionError: bob's new value was not 33: expected { Object (s, e, ...) } to equal 30
      at Context.it (test/simpleStorage.js:20:13)
      at process._tickCallback (internal/process/next_tick.js:68:7)

After you find the error and fix it all tests should pass.

Using network 'development'.
  Contract: SimpleStorage
    ✓ should verify bob and alice's favorite numbers default to 0 (59ms)
    ✓ should set bob's favorite number to 33
  2 passing (107ms)

Troubleshooting

If you encounter problems, I have a GitHub repository with a working version of this guide. In your terminal run:

git clone https://github.com/crashsite/simplestorage

If truffle compile or truffle test fails in the newly cloned folder then there may be an environmental issue. Ensure that NodeJS and NPM are installed correctly.

Further Links

• Solidity Documentation
• Truffle Documentation