Foundry Book

Creating a New Project

To start a new project with Foundry, use forge init:

$ forge init hello_foundry

This creates a new directory hello_foundry from the default template. This also initializes a new git repository.

If you want to create a new project using a different template, you would pass the --template flag, like so:

$ forge init --template https://github.com/foundry-rs/forge-template hello_template

For now, let’s check what the default template looks like:

$ cd hello_foundry
$ tree . -d -L 1
.
├── lib
├── script
├── src
└── test

4 directories

The default template comes with one dependency installed: Forge Standard Library. This is the preferred testing library used for Foundry projects. Additionally, the template also comes with an empty starter contract and a simple test.

Let’s build the project:

$ forge build
Compiling 27 files with Solc 0.8.19
Solc 0.8.19 finished in 1.08s
Compiler run successful!

And run the tests:

$ forge test
No files changed, compilation skipped

Ran 2 tests for test/Counter.t.sol:CounterTest
[PASS] testFuzz_SetNumber(uint256) (runs: 256, μ: 31054, ~: 31288)
[PASS] test_Increment() (gas: 31303)
Suite result: ok. 2 passed; 0 failed; 0 skipped; finished in 5.23ms (4.91ms CPU time)

Ran 1 test suite in 6.42ms (5.23ms CPU time): 2 tests passed, 0 failed, 0 skipped (2 total tests)

You’ll notice that two new directories have popped up: out and cache.

The out directory contains your contract artifact, such as the ABI, while the cache is used by forge to only recompile what is necessary.