start_roll.md

start_roll

fn start_roll(target: CheatTarget, block_number: u64)

Changes the block number for the given target. The change can be canceled with stop_roll.

• target - instance of CheatTarget specifying which contracts to roll
• block_number - block number to be set

For contract implementation:

// ...
#[storage]
struct Storage {
    // ...
    stored_block_number: u64
}

#[external(v0)]
impl IContractImpl of IContract<ContractState> {
    fn set_block_number(ref self: ContractState) {
        self.stored_block_number.write(starknet::get_block_info().unbox().block_number);
    }
    
    fn get_block_number(self: @ContractState) -> u64 {
        self.stored_block_number.read()
    }
}
// ...

We can use start_roll in a test to change the block number for contracts:

use snforge_std::{start_roll, CheatTarget};

#[test]
fn test_roll() {
    // ...

    start_roll(CheatTarget::One(contract_address), 234);

    dispatcher.set_block_number();
    let new_block_number = dispatcher.get_block_number();
    assert(new_block_number == 234, 'Wrong block number');
}