Request for a method to easily advance env.ledger().sequence() | Stellar Developers | Page 1

dapper vapor Oct 24, 2023, 1:57 PM

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Time is an important aspect to test in contracts but it's actually non-trival to advance time currently. Adding a env.ledger().sequence().increase(n: u32) method to progress the ledger would be quite nice. Behind the scenes I would imagine this would clone the existing env, advance the sequence by n and replace the existing env. Or some such utility

shell idol Oct 24, 2023, 2:11 PM

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There is a LedgerInfo in the testutils you can import that allows you to modify this on the existing env.

I normally write a helper method that goes something like:

use soroban_sdk::testutils::{Ledger, LedgerInfo};
...
    pub fn jump_with_sequence(env: &Env, time: u64) {
        let blocks = time / 5;
        env.ledger().set(LedgerInfo {
            timestamp: env.ledger().timestamp().saturating_add(time),
            protocol_version: 20,
            sequence_number: 
env.ledger().sequence().saturating_add(blocks as u32),
            network_id: Default::default(),
            base_reserve: 10,
            min_temp_entry_expiration: 999999,
            min_persistent_entry_expiration: 999999,
            max_entry_expiration: u32::MAX,
        });
    }

dapper vapor Oct 24, 2023, 2:12 PM

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Yeah I'm using this

fn advance_sequence(env: &mut Env) {
    let mut snapshot = env.to_snapshot();
    snapshot.sequence_number += 1;
    snapshot.timestamp = snapshot.timestamp.saturating_add(5);
    *env = Env::from_snapshot(snapshot);
    env.budget().reset_default();
}

Then use it like:

let mut env = Env::default();
...
advance_sequence(&mut env);

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Which works fine but would be nice to have an official utility since this is such a common action

near ibex Oct 24, 2023, 2:19 PM

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Yeah I agree, also it seems the current approach is not straightforward for those who are new as I've seen a couple of folks asking for this

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I guess though that the function should also have the time for every ledger to be specified

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futurenet and testnet ledgers definitely close before 5 seconds

shell idol Oct 24, 2023, 2:29 PM

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there are also situations where passing too many sequence numbers is not good for testing edge cases, like with a fuzzer that jumps an arbitrary amount of blocks.

Reason being is things will expire and cause "bad" errors.

vapid hamlet Oct 24, 2023, 3:25 PM

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I guess though that the function should also have the time for every ledger to be specified
I don't think you need to optimize for testnet (and in general you probably should be advancing either sequence or time - these are correlated, but there are no guarantees on when exactly certain ledger is applied)

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FWIW this is a good thing to just open a feature request for rs-soroban-sdk OR just do a quick PR - that should be just one or two lines with env.ledger().with_mut(|li| li.sequence_number += 1;)

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FWIW with_mut is probably much better for anything else ledger-related (you don't need to create snapshots for this)

#Request for a method to easily advance env.ledger().sequence()