Foundry makes developing with existing projects have no overhead.
First, clone the project and run
forge install inside the project directory.
$ git clone https://github.com/PaulRBerg/foundry-template $ cd foundry-template $ forge install
forge install to install the submodule dependencies that are in the project.
To build, use
$ forge build Compiling 10 files with 0.8.15 Solc 0.8.15 finished in 4.35s Compiler run successful
And to test, use
$ forge test No files changed, compilation skipped Running 1 test for test/Greeter.t.sol:GreeterTest [PASS] testSetGm() (gas: 107402) Test result: ok. 1 passed; 0 failed; finished in 4.77ms