First Steps With Starknet Foundry

In this section we provide an overview of Starknet Foundry snforge command line tool. We demonstrate how to create a new project, compile, and test it.

To start a new project with Starknet Foundry, run snforge new

$ snforge new hello_starknet

📝 Note

By default, snforge new creates a project with a simple HelloStarknet contract. You can create a different project using the --template flag. To see the list of available templates, refer to the snforge new documentation

Let's check out the project structure

$ cd hello_starknet
$ tree . -L 1

.
├── Scarb.lock
├── Scarb.toml
├── snfoundry.toml
├── src
└── tests

2 directories, 3 files

• src/ contains source code of all your contracts.
• tests/ contains tests.
• Scarb.toml contains configuration of the project as well as of snforge
• Scarb.lock a locking mechanism to achieve reproducible dependencies when installing the project locally

And run tests with snforge test

$ snforge test

Collected 2 test(s) from hello_starknet package
Running 0 test(s) from src/
Running 2 test(s) from tests/
[PASS] hello_starknet_integrationtest::test_contract::test_cannot_increase_balance_with_zero_value (l1_gas: ~0, l1_data_gas: ~96, l2_gas: ~360000)
[PASS] hello_starknet_integrationtest::test_contract::test_increase_balance (l1_gas: ~0, l1_data_gas: ~192, l2_gas: ~480000)
Tests: 2 passed, 0 failed, 0 ignored, 0 filtered out

Using snforge With Existing Scarb Projects

To use snforge with existing Scarb projects, make sure you have declared the snforge_std package as your project development dependency.

Add the following line under [dev-dependencies] section in the Scarb.toml file.

# ...

[dev-dependencies]
snforge_std = "0.49.0"

Make sure that the above version matches the installed snforge version. You can check the currently installed version with

$ snforge --version

snforge 0.33.0

It is also possible to add this dependency using scarb add command.

$ scarb add snforge_std@0.33.0 --dev

Additionally, ensure that starknet-contract target is enabled in the Scarb.toml file.

# ...
[[target.starknet-contract]]

📝 Note

You can additionally specify scarb settings to avoid compiling Cairo plugin which snforge_std depends on. The plugin is written in Rust and, by default, is compiled locally on the user's side.

[tool.scarb]  
allow-prebuilt-plugins = ["snforge_std"]

This configuration requires Scarb version >= 2.10.0 .