Deploy with Truffle

This page outlines the steps for deploying and testing contracts in the Neon EVM using the Truffle tool. Truffle can be useful for those involved in the development and maintenance of the Neon EVM.

Before beginning the tutorial below, make sure that you have properly configured Truffle for the Neon EVM.

How to Use Truffle: A Tutorial

The example this tutorial is based on is located in this repository.

By the end of this tutorial, you will deploy a contract describing an ERC-20 token to the Neon Devnet, and subsequently mint 1 test token that is deposited to the first wallet specified in the configuration file (see above).

Step 1: Installation

Note: This page is just a quickstart based on a specific example program. For more details on installing Truffle, refer to the Truffle documentation.

Using Git, clone the example Truffle project from the remote repository and navigate to it:

git clone https://github.com/neonlabsorg/examples.git
cd examples/simple-erc20-truffle

Then, run the following command:

npm install

This will install all the necessary packages to continue with the example. These packages include the Truffle and HDWalletProvider libraries.

If the above command results in an error, run:

npm cache clear --force
npm install

Step 2: Set Up MetaMask Accounts

To interact with the soon-to-be-deployed contracts, you'll need to create two new accounts in MetaMask. Before you begin, make sure that MetaMask is connected to the Neon Devnet.

In MetaMask, create two new accounts. This can be done by clicking on your current account's icon in the top right of the MetaMask extension pop-up, and then clicking on 'Create an Account' in the drop-down menu that appears. Then, obtain some Devnet NEON tokens for these accounts (up to 100 NEON per account) using the NeonFaucet.

Finally, copy the new accounts' private keys and paste them into the truffle-config.js file described above, replacing the placeholder text in lines 11 and 12 of that file. To obtain the private keys, click on the three vertical dots to the right of your currently displayed account name and wallet address. In this drop-down menu, click on 'Account Details', then on 'Export Private Key', and enter your password and click 'Confirm' to get access to the private key for that account.

Note: When adding the private keys to the configuration file, make sure to add the prefix 0x to the key obtained via MetaMask.

Step 3: Compile Contracts

All of the contracts are located in the project's contracts/ directory. Before these contracts can be run, they must first be compiled. To compile the project's contracts, run the following command:

./node_modules/.bin/truffle compile

After running this step, you should see output similar to the following:

Compiling your contracts...
===========================
✔ Fetching solc version list from solc-bin. Attempt #1
✔ Downloading compiler. Attempt #1.
✔ Fetching solc version list from solc-bin. Attempt #1
> Compiling ./contracts/ERC20.sol
> Compiling ./contracts/IERC20.sol
> Artifacts written to /tmp/test--947955-ciBGiafT1chM
> Compiled successfully using:
   - solc: 0.8.16+commit.07a7930e.Emscripten.clang

For the first run, all contracts will be compiled. During subsequent runs, only contracts that have changed since the last compilation will be compiled again.

Step 4: Run Tests

Make sure to test your code before you migrate it to the network. All test files should be located under the test/ directory.

To run all tests, simply run the command below. Make sure to specify the neonlabs network to deploy to with the --network option.

./node_modules/.bin/truffle test --network neonlabs

This command compiles all the contracts in the contracts/, deploys them to the Neon Devnet, and runs all the tests in the test/ directory. The output should look something like this:

Compiling your contracts...
===========================
✔ Fetching solc version list from solc-bin. Attempt #1
✔ Fetching solc version list from solc-bin. Attempt #1
> Everything is up to date, there is nothing to compile.


  Contract: TestERC20
    ✓ should successfully mint 10000 ERC20 in the first account (5288ms)
    ✓ should transfer token correctly (7335ms)


  2 passing (13s)

Step 5: Run Migrations

Migrations are a set of managed deployment scripts used to deploy contracts to the network. These scripts, which are JavaScript files, are contained in the project's migrations/ directory.

To run migrations to deploy the contracts, run the migrate command. Make sure to specify the neonlabs network to deploy to with the --network option.

./node_modules/.bin/truffle migrate --network neonlabs

After running this command, you should see console output similar to the following:

Compiling your contracts...
===========================
✔ Fetching solc version list from solc-bin. Attempt #1
✔ Fetching solc version list from solc-bin. Attempt #1
> Everything is up to date, there is nothing to compile.


Starting migrations...
======================
> Network name:    'neonlabs'
> Network id:      245022926
> Block gas limit: 260057650590124 (0xec8563e271ac)


1_erc20.js
==========

   Deploying 'ERC20'
   -----------------
   > transaction hash:    0x54db68667335ab2c6e8aeee1080b30ac39209186e2f0c12dba97b7130d923382
   > Blocks: 11           Seconds: 4
   > contract address:    0x7364DA3a4989898Ac2d466611Ce4b957885DF7B8
   > block number:        158638454
   > block timestamp:     1661872308
   > account:             0xf71c4DACa893E5333982e2956C5ED9B648818376
   > balance:             8.205758048453800748
   > gas used:            43936740 (0x29e6be4)
   > gas price:           137.5017384 gwei
   > value sent:          0 ETH
   > total cost:          6.041378129628816 ETH

   > Saving artifacts
   -------------------------------------
   > Total cost:     6.041378129628816 ETH

Summary
=======
> Total deployments:   1
> Final cost:          6.041378129628816 ETH

Step 6: Connect Project to MetaMask

To import your project as an asset in MetaMask, follow the instructions here and use the contract address from the previous step as the 'Token Contract Address' in MetaMask.

Once you complete this final step, you will be able to see your new ERC-20 assets in the MetaMask profiles of the new test accounts.