Declare, deploy, and interact with a smart contract using Staknet Foundry

This tutorial guides you through deploying a Cairo smart contract onto Starknet Devnet.

Prerequisites

The following tools are installed:

Starknet Foundry
Scarb
Starknet Devnet

Contract deployment and interaction

Create a new project

Create a new project using the snforge command. Let’s name it hello_starknet.

snforge init hello_starknet

You will get to scarb.toml file as below.

[package]
name = "hello_starknet"
version = "0.1.0"
edition = "2023_11"

# See more keys and their definitions at https://docs.swmansion.com/scarb/docs/reference/manifest.html

[dependencies]
starknet = "2.5.4"

[dev-dependencies]
snforge_std = { git = "https://github.com/foundry-rs/starknet-foundry", tag = "v0.24.0" }

[[target.starknet-contract]]
sierra = true

[scripts]
test = "snforge test"

Then you can check the lib.cairo file.

#[starknet::interface]
pub trait IHelloStarknet<TContractState> {
    fn increase_balance(ref self: TContractState, amount: felt252);
    fn get_balance(self: @TContractState) -> felt252;
}

#[starknet::contract]
mod HelloStarknet {
    #[storage]
    struct Storage {
        balance: felt252,
    }

    #[abi(embed_v0)]
    impl HelloStarknetImpl of super::IHelloStarknet<ContractState> {
        fn increase_balance(ref self: ContractState, amount: felt252) {
            assert(amount != 0, 'Amount cannot be 0');
            self.balance.write(self.balance.read() + amount);
        }

        fn get_balance(self: @ContractState) -> felt252 {
            self.balance.read()
        }
    }
}

Compile contract and import an account

Compile your contract using scarb.

scarb build

Having compiled the smart contract, it’s time to import a prefunded account from Starknet Devnet.

Create profile and import account

Launch Starknet Devnet.

starknet-devnet --seed 42

After starting Starknet Devnet, a list of accounts is automatically generated and deployed. We use the --seed flag to keep the same pre-configured accounts each time we initiate Starknet Devnet.

We look at the first generated account.

| Account address |  0x516dd7e4d25da119abf4d61bbd9a4aa79e19dddb2304dc2fe1b6f009a3e5beb
| Private key     |  0xb10070a1eaf2a466673432eb0ef138ba
| Public key      |  0x6115113976012215e40010694301b5626d8dc7ca8acec3a09c6e4f40835a13e

With this information, we have to import that account and create our profile to interact with Starknet Foundry. Execute:

sncast --url http://127.0.0.1:5050 account add --name my_devnet_account \
--address 0x516dd7e4d25da119abf4d61bbd9a4aa79e19dddb2304dc2fe1b6f009a3e5beb \
--private-key 0xb10070a1eaf2a466673432eb0ef138ba --type oz --add-profile my_profile

Upon successful command execution, you’ll obtain a snfoundry.toml with your profile information.

Declare contract

To declare your contract, execute:

sncast --profile my_profile declare --contract-name HelloStarknet

Upon successful command execution, you’ll obtain a contract class hash. This unique hash serves as the identifier for your contract class within Starknet.

class_hash: 0x183cc71fac33a2823d5afb59ed7679e2e872b305acff9c57ebe0e70fea59ef3
transaction_hash: 0x6262495c4ff2a25c7d79a27803662db6c738aaa3428ce531a218c84ff6c0340

Deploy contract

starkli --profile <profile> deploy <class_hash_of_the_contract_to_be_deployed> --constructor-calldata <constructor_calldata>...

For this contract, we did not specify a constructor function, so we don’t need to pass any constructor arguments.

sncast --profile my_profile deploy --class-hash 0x183cc71fac33a2823d5afb59ed7679e2e872b305acff9c57ebe0e70fea59ef3

After running, expect an output similar to:

contract_address: 0x39a9a0f739ad27293656951fb65f715d3d1bf45947b45da92554969e1d41f10
transaction_hash: 0x2bc40a931d6e27e304cb1cda492cdeff16f32156fb45571c23f8ed5feae182d

Call contract

The first parameter is your profile, the second parameter is the contract address, the third parameter is the function to be called.

sncast --profile my_profile call --contract-address 0x39a9a0f739ad27293656951fb65f715d3d1bf45947b45da92554969e1d41f10 --function get_balance

After running, expect an output similar to:

command: call
response: [0x0]

It means the value of balance is zero.

Invoke contract

The first parameter is your profile, the second parameter is the contract address, the third parameter is the function to be invoked, and the fourth parameter is the function parameter. Let’s set the value of balance to 6.

sncast --profile my_profile invoke --contract-address 0x39a9a0f739ad27293656951fb65f715d3d1bf45947b45da92554969e1d41f10 --function increase_balance --calldata 6

Let’s retrieve the new value of balance

sncast --profile my_profile call --contract-address 0x39a9a0f739ad27293656951fb65f715d3d1bf45947b45da92554969e1d41f10 --function get_balance

After running, expect an output similar to:

command: call
response: [0x6]

Awesome! You deployed and interacted with a Cairo smart contract using Starknet Devnet and Starknet Foundry! You can now build more complex smart contracts and interact with them using the same process.