solana-runtime 4.1.0-rc.0

use {
    crate::{bank::Bank, validated_reward_certificate::ValidatedRewardCert},
    epoch_inflation_account_state::{EpochInflationAccountState, EpochInflationState},
    log::info,
    solana_account::{AccountSharedData, ReadableAccount, WritableAccount},
    solana_clock::{Epoch, Slot},
    solana_pubkey::Pubkey,
    solana_vote::vote_account::VoteAccount,
    solana_vote_interface::state::{LandedVote, Lockout},
    solana_vote_program::vote_state::handler::VoteStateHandler,
    std::collections::{HashSet, VecDeque},
    thiserror::Error,
};

pub mod epoch_inflation_account_state;

/// Different types of errors that can happen when calculating and paying voting reward.
#[derive(Debug, Error)]
pub enum CalcVoteRewardUpdateVoteStatesError {
    #[error("missing EpochInflationAccountState for current slot {current_slot}")]
    MissingEpochInflationAccountState { current_slot: Slot },
    #[error("missing epoch stakes for reward_slot {reward_slot} in current_slot {current_slot}")]
    MissingEpochStakes {
        reward_slot: Slot,
        current_slot: Slot,
    },
    #[error(
        "validator {pubkey} missing in current slot {current_slot} for reward slot {reward_slot}"
    )]
    MissingRewardSlotValidator {
        pubkey: Pubkey,
        reward_slot: Slot,
        current_slot: Slot,
    },
    #[error(
        "missing validator stake info for reward epoch {reward_epoch} in current_slot \
         {current_slot}"
    )]
    NoEpochValidatorStake {
        reward_epoch: Epoch,
        current_slot: Slot,
    },
}

/// Calculates voting rewards based on the `reward_cert` and updates fields in the vote account
/// based on the calculated rewards and the `final_cert`.
pub(super) fn calc_vote_rewards_update_vote_states(
    bank: &Bank,
    reward_cert: Option<ValidatedRewardCert>,
    final_cert_input: Option<(&HashSet<Pubkey>, Slot)>,
) -> Result<(), CalcVoteRewardUpdateVoteStatesError> {
    let (reward_slot, validators_to_reward) = if let Some(reward_cert) = reward_cert {
        reward_cert.into_parts()
    } else {
        return Ok(());
    };

    let current_slot = bank.slot();
    let (reward_slot_accounts, reward_slot_total_stake) = {
        let epoch_stakes = bank.epoch_stakes_from_slot(reward_slot).ok_or(
            CalcVoteRewardUpdateVoteStatesError::MissingEpochStakes {
                reward_slot,
                current_slot,
            },
        )?;
        (
            epoch_stakes.stakes().vote_accounts().as_ref(),
            epoch_stakes.total_stake(),
        )
    };

    // This assumes that if the epoch_schedule ever changes, the new schedule will maintain correct
    // info about older slots as well.
    let reward_epoch = bank.epoch_schedule.get_epoch(reward_slot);
    let epoch_state = {
        let epoch_inflation_account_state = EpochInflationAccountState::new_from_bank(bank);
        // This function should only be called after alpenglow is active and the slot in the the epoch
        // that activated Alpenglow should have created the account.
        debug_assert!(epoch_inflation_account_state.is_some());
        epoch_inflation_account_state
            .ok_or(
                CalcVoteRewardUpdateVoteStatesError::MissingEpochInflationAccountState {
                    current_slot,
                },
            )?
            .get_epoch_state(reward_epoch)
            .ok_or(CalcVoteRewardUpdateVoteStatesError::NoEpochValidatorStake {
                reward_epoch,
                current_slot,
            })?
    };

    let current_vote_accounts = bank.vote_accounts();
    let current_slot_leader_vote_pubkey = bank.leader().vote_address;
    // Adding 1 to capacity in case the current leader was not in the aggregate and paying it
    // triggers a reallocation.
    let mut paid_vote_accounts = Vec::with_capacity(validators_to_reward.len().saturating_add(1));
    let mut total_leader_reward = 0u64;
    let current_epoch = bank.epoch();
    for validator_to_reward in validators_to_reward {
        let (reward_slot_validator_stake, _) =
            reward_slot_accounts.get(&validator_to_reward).ok_or(
                CalcVoteRewardUpdateVoteStatesError::MissingRewardSlotValidator {
                    pubkey: validator_to_reward,
                    reward_slot,
                    current_slot,
                },
            )?;
        let (validator_reward, add_leader_reward) = calculate_reward(
            &epoch_state,
            reward_slot_total_stake,
            *reward_slot_validator_stake,
        );
        total_leader_reward = total_leader_reward.saturating_add(add_leader_reward);

        if current_slot_leader_vote_pubkey == validator_to_reward {
            // Current slot's leader's node pubkey is associated with exactly one vote
            // pubkey and this reward is for this vote pubkey.  The reward will be paid.
            // However, we haven't finished calculating the total rewards for the leader yet.
            // `total_leader_reward` be paid at the end of the function.
            total_leader_reward = total_leader_reward.saturating_add(validator_reward);
            continue;
        }

        // The reward was not for a vote pubkey associated with the current slot's leader's node pubkey.
        // We can pay it into the vote account immediately.
        let Some((_, current_slot_account)) = current_vote_accounts.get(&validator_to_reward)
        else {
            info!(
                "validator {validator_to_reward} was present for reward_slot {reward_slot} but is \
                 absent for current_slot {current_slot}"
            );
            continue;
        };
        if let Some(account_data) = update_vote_account(
            current_epoch,
            reward_slot,
            current_slot_account,
            validator_to_reward,
            validator_reward,
            &final_cert_input,
        ) {
            paid_vote_accounts.push((validator_to_reward, account_data));
        }
    }

    // We have computed the final `total_leader_rewards` now.  We can pay it into the leader's
    // vote account.
    if total_leader_reward != 0 {
        match current_vote_accounts.get(&current_slot_leader_vote_pubkey) {
            Some((_, leader_account)) => {
                if let Some(account_data) = update_vote_account(
                    current_epoch,
                    reward_slot,
                    leader_account,
                    current_slot_leader_vote_pubkey,
                    total_leader_reward,
                    &final_cert_input,
                ) {
                    paid_vote_accounts.push((current_slot_leader_vote_pubkey, account_data));
                }
            }
            None => {
                info!(
                    "Current slot {current_slot}'s leader's account \
                     {current_slot_leader_vote_pubkey} not found.  It will not be paid."
                )
            }
        }
    }

    bank.store_accounts((current_slot, paid_vote_accounts.as_slice()));
    Ok(())
}

/// Computes the voting reward in Lamports.
///
/// Returns `(validator rewards, leader rewards)`.
fn calculate_reward(
    epoch_state: &EpochInflationState,
    total_stake_lamports: u64,
    validator_stake_lamports: u64,
) -> (u64, u64) {
    // Rewards are computed as following:
    // per_slot_inflation = epoch_validator_rewards_lamports / slots_per_epoch
    // fractional_stake = validator_stake / total_stake_lamports
    // rewards = fractional_stake * per_slot_inflation
    //
    // The code below is equivalent but changes the order of operations to maintain precision

    let numerator =
        epoch_state.max_possible_validator_reward as u128 * validator_stake_lamports as u128;
    let denominator = epoch_state.slots_per_epoch as u128 * total_stake_lamports as u128;

    // SAFETY: the result should fit in u64 because we do not expect the inflation in a single
    // epoch to exceed u64::MAX.
    let reward_lamports: u64 = (numerator / denominator).try_into().unwrap();
    // As per the Alpenglow SIMD, the rewards are split equally between the validators and the leader.
    let validator_reward_lamports = reward_lamports / 2;
    let leader_reward_lamports = reward_lamports - validator_reward_lamports;
    (validator_reward_lamports, leader_reward_lamports)
}

/// Deserializes the state from the `account` and updates various fields in it.
///
/// If successful, returns the `AccountSharedData` that can be stored back into a `Bank`.
fn update_vote_account(
    current_epoch: Epoch,
    reward_slot: Slot,
    account: &VoteAccount,
    validator_vote_pubkey: Pubkey,
    reward: u64,
    final_cert_input: &Option<(&HashSet<Pubkey>, Slot)>,
) -> Option<AccountSharedData> {
    let versions = bincode::deserialize(account.account().data()).ok()?;
    let mut handle = VoteStateHandler::try_new_from_vote_state_versions(versions).ok()?;
    update_vote_state(
        &mut handle,
        reward_slot,
        current_epoch,
        reward,
        validator_vote_pubkey,
        final_cert_input,
    );
    let mut paid_account = AccountSharedData::new(
        account.lamports(),
        account.account().data().len(),
        account.owner(),
    );
    handle
        .serialize_into(paid_account.data_as_mut_slice())
        .ok()?;
    Some(paid_account)
}

/// Updates `epoch_credits`, `root_slot`, and `votes` in vote state using the rewards and finalization
/// certificates from the footer.
///
/// `epoch_credits` are updated to record the rewards that the vote account has earned.
///
/// Downstream tooling expects these fields to be be set:
/// - `root_slot`, a validator's latest finalized & replayed slot
/// - `votes`, a validator's latest vote
///
/// `votes` is consumed for health monitoring, we require it to be within `DELINQUENT_VALIDATOR_SLOT_DISTANCE`
/// of the tip of the chain to be considered healthy.
///
/// `root_slot` is similarly used by various tooling (e.g. stake delegation) to determine whether the validator
/// is healthy to interact with  and also is required to be within `DELINQUENT_VALIDATOR_SLOT_DISTANCE` of the tip.
///
/// Until we overhaul vote state we continue populating these two fields similar to TowerBFT:
/// - `root_slot` is populated from the footer finalization certificate
/// - `votes` is populated from the footer rewards aggregate
fn update_vote_state(
    handle: &mut VoteStateHandler,
    reward_slot: Slot,
    reward_epoch: Epoch,
    reward: u64,
    validator_vote_pubkey: Pubkey,
    final_cert_input: &Option<(&HashSet<Pubkey>, Slot)>,
) {
    handle.increment_credits(reward_epoch, reward);
    if let Some((signers, slot)) = final_cert_input {
        if signers.contains(&validator_vote_pubkey) {
            handle.set_root_slot(Some(*slot));
        }
    }

    let latest_root_or_reward = handle.root_slot().unwrap_or(reward_slot).max(reward_slot);
    handle.set_votes(VecDeque::from([LandedVote {
        lockout: Lockout::new(latest_root_or_reward),
        latency: 0,
    }]));
}

#[cfg(test)]
mod tests {
    use {
        super::*,
        crate::{
            bank_forks::BankForks,
            genesis_utils::{
                ValidatorVoteKeypairs, create_genesis_config_with_alpenglow_vote_accounts,
            },
            test_utils::new_rand_vote_account,
            validated_block_finalization::ValidatedBlockFinalizationCert,
        },
        agave_votor_messages::{
            consensus_message::{Certificate, CertificateType},
            reward_certificate::NUM_SLOTS_FOR_REWARD,
        },
        bitvec::prelude::*,
        rand::seq::IndexedRandom,
        solana_account::ReadableAccount,
        solana_bls_signatures::{BLS_SIGNATURE_AFFINE_SIZE, Signature as BLSSignature},
        solana_epoch_schedule::EpochSchedule,
        solana_genesis_config::GenesisConfig,
        solana_hash::Hash,
        solana_keypair::Keypair,
        solana_leader_schedule::SlotLeader,
        solana_native_token::LAMPORTS_PER_SOL,
        solana_rent::Rent,
        solana_signer::Signer,
        solana_signer_store::encode_base2,
        std::sync::{Arc, RwLock},
    };

    fn new_bank_for_tests(
        leader: SlotLeader,
        genesis_config: &GenesisConfig,
    ) -> (Arc<Bank>, Arc<RwLock<BankForks>>) {
        let bank = Bank::new_with_paths_for_tests(genesis_config, None, vec![], Some(leader));
        assert_eq!(*bank.leader(), leader);
        bank.wrap_with_bank_forks_for_tests()
    }

    fn new_bank_from_parent(parent_bank: Arc<Bank>, slot: Slot) -> Arc<Bank> {
        let leader = *parent_bank.leader();
        Arc::new(Bank::new_from_parent(parent_bank, leader, slot))
    }

    fn vote_state_from_account(account: &AccountSharedData) -> VoteStateHandler {
        let versions = bincode::deserialize(account.data()).unwrap();
        VoteStateHandler::try_new_from_vote_state_versions(versions).unwrap()
    }

    fn vote_state_from_bank(bank: &Bank, vote_pubkey: &Pubkey) -> VoteStateHandler {
        let vote_accounts = bank.vote_accounts();
        let (_, vote_account) = vote_accounts.get(vote_pubkey).unwrap();
        vote_state_from_account(vote_account.account())
    }

    fn build_fast_finalization_cert(
        bank: &Bank,
        signing_ranks: &[usize],
    ) -> (HashSet<Pubkey>, Slot) {
        let slot = bank.slot();
        let block_id = Hash::new_unique();
        let cert_type = CertificateType::FinalizeFast(slot, block_id);
        let max_rank = signing_ranks.iter().copied().max().unwrap_or(0);
        let mut bitvec = BitVec::<u8, Lsb0>::repeat(false, max_rank.saturating_add(1));
        for &rank in signing_ranks {
            bitvec.set(rank, true);
        }
        let bitmap = encode_base2(&bitvec).unwrap();

        let cert = Certificate {
            cert_type,
            signature: BLSSignature([0; BLS_SIGNATURE_AFFINE_SIZE]),
            bitmap,
        };
        let (signers, cert, _) =
            ValidatedBlockFinalizationCert::from_validated_fast(cert, bank).into_parts();
        (signers, cert.cert_type.slot())
    }

    #[test]
    fn calculate_voting_reward_does_not_panic() {
        // the current circulating supply is about 566M.  The most extreme numbers are when all of
        // it is staked by a single validator.
        let circulating_supply = 566_000_000 * LAMPORTS_PER_SOL;

        let (bank, _bank_forks) =
            new_bank_for_tests(SlotLeader::new_unique(), &GenesisConfig::default());
        let validator_rewards_lamports =
            bank.calculate_epoch_inflation_rewards(circulating_supply, 1);

        let epoch_state = EpochInflationState {
            slots_per_epoch: bank.epoch_schedule.slots_per_epoch,
            max_possible_validator_reward: validator_rewards_lamports,
            epoch: 1234,
        };

        calculate_reward(&epoch_state, circulating_supply, circulating_supply);
    }

    #[test]
    fn increment_credits_works() {
        let mut handle = VoteStateHandler::default_v4();
        let epoch = 1234;
        let credits = 543432;
        handle.increment_credits(epoch, credits);
        let (got_epoch, got_final_credits, got_initial_credits) =
            *handle.epoch_credits().last().unwrap();
        assert_eq!(got_epoch, epoch);
        assert_eq!(got_final_credits, credits);
        assert_eq!(got_initial_credits, 0);
    }

    #[test]
    fn pay_reward_works() {
        let account =
            VoteAccount::try_from(new_rand_vote_account(&mut rand::rng(), None, true)).unwrap();
        let epoch = 1234;
        let reward = 3453423;
        let account_shared_data =
            update_vote_account(epoch, 0, &account, Pubkey::default(), reward, &None).unwrap();
        let vote_state = vote_state_from_account(&account_shared_data);
        assert_eq!(reward, vote_state.epoch_credits().last().unwrap().1);
    }

    fn calc_reward_for_test(
        prev_bank: &Bank,
        bank: &Bank,
        total_stake: u64,
        stake_voted: u64,
    ) -> u64 {
        let epoch_inflation =
            bank.calculate_epoch_inflation_rewards(prev_bank.capitalization(), prev_bank.epoch());
        let numerator = epoch_inflation as u128 * stake_voted as u128;
        let denominator = bank.epoch_schedule.slots_per_epoch as u128 * total_stake as u128;
        let reward: u64 = (numerator / denominator).try_into().unwrap();
        reward / 2
    }

    #[test]
    fn calculate_and_pay_works() {
        let num_validators = 100;
        let per_validator_stake = LAMPORTS_PER_SOL * 100;
        let num_validators_to_reward = 10;

        let validator_keypairs = (0..num_validators)
            .map(|_| ValidatorVoteKeypairs::new_rand())
            .collect::<Vec<_>>();
        let mut genesis_config = create_genesis_config_with_alpenglow_vote_accounts(
            1_000_000_000,
            &validator_keypairs,
            vec![per_validator_stake; validator_keypairs.len()],
        )
        .genesis_config;
        genesis_config.epoch_schedule = EpochSchedule::without_warmup();
        genesis_config.rent = Rent::default();

        let validator_keypairs_to_reward = validator_keypairs
            .choose_multiple(&mut rand::rng(), num_validators_to_reward as usize)
            .collect::<Vec<_>>();

        let validator_pubkeys_to_reward = validator_keypairs_to_reward
            .iter()
            .map(|v| v.vote_keypair.pubkey())
            .collect::<Vec<_>>();
        let leader_vote_pubkey = validator_keypairs_to_reward[0].vote_keypair.pubkey();
        let leader_node_pubkey = validator_keypairs_to_reward[0].node_keypair.pubkey();
        let slot_leader = SlotLeader {
            id: leader_node_pubkey,
            vote_address: leader_vote_pubkey,
        };

        let (prev_bank, _bank_forks) = new_bank_for_tests(slot_leader, &genesis_config);
        let current_slot = prev_bank
            .epoch_schedule
            .get_first_slot_in_epoch(prev_bank.epoch() + 1)
            + NUM_SLOTS_FOR_REWARD;
        let bank = new_bank_from_parent(prev_bank.clone(), current_slot);
        let reward_slot = current_slot - NUM_SLOTS_FOR_REWARD;

        calc_vote_rewards_update_vote_states(
            &bank,
            Some(ValidatedRewardCert::new_for_tests(
                reward_slot,
                validator_pubkeys_to_reward.clone(),
            )),
            None,
        )
        .unwrap();

        let vote_accounts = bank.vote_accounts();
        let rewards = validator_pubkeys_to_reward
            .iter()
            .map(|validator| {
                let (_, vote_account) = vote_accounts.get(validator).unwrap();
                let vote_state = vote_state_from_account(vote_account.account());
                assert_eq!(vote_state.epoch_credits().len(), 1);
                let got_reward = vote_state.epoch_credits()[0].1;
                let total_stake = bank
                    .epoch_stakes_from_slot(reward_slot)
                    .unwrap()
                    .total_stake();
                let expected_validator_reward =
                    calc_reward_for_test(&prev_bank, &bank, total_stake, per_validator_stake);
                if *validator != leader_vote_pubkey {
                    assert_eq!(got_reward, expected_validator_reward);
                }
                got_reward
            })
            .collect::<Vec<_>>();
        let expected_leader_reward = rewards.last().unwrap()
            * validator_pubkeys_to_reward.len() as u64
            + rewards.last().unwrap();
        assert_eq!(expected_leader_reward, rewards[0]);
    }

    #[test]
    fn calculate_and_pay_sets_root_slot_for_signer_in_final_cert() {
        let validator_keypairs = (0..4)
            .map(|_| ValidatorVoteKeypairs::new_rand())
            .collect::<Vec<_>>();
        let per_validator_stake = LAMPORTS_PER_SOL * 100;
        let mut genesis_config = create_genesis_config_with_alpenglow_vote_accounts(
            1_000_000_000,
            &validator_keypairs,
            vec![per_validator_stake; validator_keypairs.len()],
        )
        .genesis_config;
        genesis_config.epoch_schedule = EpochSchedule::without_warmup();
        genesis_config.rent = Rent::default();

        let leader_vote_pubkey = validator_keypairs[0].vote_keypair.pubkey();
        let leader_node_pubkey = validator_keypairs[0].node_keypair.pubkey();
        let slot_leader = SlotLeader {
            id: leader_node_pubkey,
            vote_address: leader_vote_pubkey,
        };
        let target_vote_pubkey = validator_keypairs[1].vote_keypair.pubkey();

        let (prev_bank, _bank_forks) = new_bank_for_tests(slot_leader, &genesis_config);
        let current_slot = prev_bank
            .epoch_schedule
            .get_first_slot_in_epoch(prev_bank.epoch() + 1)
            + NUM_SLOTS_FOR_REWARD;
        let bank = new_bank_from_parent(prev_bank.clone(), current_slot);
        let reward_slot = current_slot - NUM_SLOTS_FOR_REWARD;

        let cert_rank = {
            let rank_map = bank
                .epoch_stakes_from_slot(bank.slot())
                .unwrap()
                .bls_pubkey_to_rank_map();
            (0..rank_map.len())
                .find_map(|rank| {
                    rank_map.get_pubkey_stake_entry(rank).and_then(|entry| {
                        (entry.vote_account_pubkey == target_vote_pubkey).then_some(rank)
                    })
                })
                .unwrap()
        };
        let (final_cert_signers, final_cert_slot) =
            build_fast_finalization_cert(&bank, &[cert_rank]);

        calc_vote_rewards_update_vote_states(
            &bank,
            Some(ValidatedRewardCert::new_for_tests(
                reward_slot,
                vec![target_vote_pubkey],
            )),
            Some((&final_cert_signers, final_cert_slot)),
        )
        .unwrap();

        let handle = vote_state_from_bank(&bank, &target_vote_pubkey);
        assert_eq!(handle.root_slot(), Some(final_cert_slot));
        assert_eq!(handle.votes().len(), 1);
        assert_eq!(
            handle.votes().front().unwrap().lockout.slot(),
            final_cert_slot.max(reward_slot)
        );
    }

    #[test]
    fn calculate_and_pay_uses_reward_slot_vote_when_signer_absent_from_final_cert() {
        let validator_keypairs = (0..4)
            .map(|_| ValidatorVoteKeypairs::new_rand())
            .collect::<Vec<_>>();
        let per_validator_stake = LAMPORTS_PER_SOL * 100;
        let mut genesis_config = create_genesis_config_with_alpenglow_vote_accounts(
            1_000_000_000,
            &validator_keypairs,
            vec![per_validator_stake; validator_keypairs.len()],
        )
        .genesis_config;
        genesis_config.epoch_schedule = EpochSchedule::without_warmup();
        genesis_config.rent = Rent::default();

        let leader_node_pubkey = validator_keypairs[0].node_keypair.pubkey();
        let leader_vote_pubkey = validator_keypairs[0].vote_keypair.pubkey();
        let target_vote_pubkey = validator_keypairs[1].vote_keypair.pubkey();
        let slot_leader = SlotLeader {
            id: leader_node_pubkey,
            vote_address: leader_vote_pubkey,
        };
        let non_target_vote_pubkey = validator_keypairs[2].vote_keypair.pubkey();

        let (prev_bank, _bank_forks) = new_bank_for_tests(slot_leader, &genesis_config);
        let current_slot = prev_bank
            .epoch_schedule
            .get_first_slot_in_epoch(prev_bank.epoch() + 1)
            + NUM_SLOTS_FOR_REWARD;
        let bank = new_bank_from_parent(prev_bank.clone(), current_slot);
        let reward_slot = current_slot - NUM_SLOTS_FOR_REWARD;

        let cert_rank = {
            let rank_map = bank
                .epoch_stakes_from_slot(bank.slot())
                .unwrap()
                .bls_pubkey_to_rank_map();
            (0..rank_map.len())
                .find_map(|rank| {
                    rank_map.get_pubkey_stake_entry(rank).and_then(|entry| {
                        (entry.vote_account_pubkey == non_target_vote_pubkey).then_some(rank)
                    })
                })
                .unwrap()
        };
        let (final_cert_signers, final_cert_slot) =
            build_fast_finalization_cert(&bank, &[cert_rank]);

        calc_vote_rewards_update_vote_states(
            &bank,
            Some(ValidatedRewardCert::new_for_tests(
                reward_slot,
                vec![target_vote_pubkey],
            )),
            Some((&final_cert_signers, final_cert_slot)),
        )
        .unwrap();

        let vote_state = vote_state_from_bank(&bank, &target_vote_pubkey);
        assert_eq!(vote_state.root_slot(), None);
        assert_eq!(vote_state.votes().len(), 1);
        assert_eq!(
            vote_state.votes().front().unwrap().lockout.slot(),
            reward_slot
        );
    }

    #[test]
    fn leader_with_multiple_vote_accounts_not_paid() {
        let num_validators = 5;
        let per_validator_stake = LAMPORTS_PER_SOL * 100;
        let node_keypair = Keypair::new();

        let validator_keypairs = (0..num_validators)
            .map(|_| {
                ValidatorVoteKeypairs::new(
                    node_keypair.insecure_clone(),
                    Keypair::new(),
                    Keypair::new(),
                )
            })
            .collect::<Vec<_>>();
        let mut genesis_config = create_genesis_config_with_alpenglow_vote_accounts(
            1_000_000_000,
            &validator_keypairs,
            vec![per_validator_stake; validator_keypairs.len()],
        )
        .genesis_config;
        genesis_config.epoch_schedule = EpochSchedule::without_warmup();
        genesis_config.rent = Rent::default();

        let node_pubkey = node_keypair.pubkey();
        let vote_pubkey = validator_keypairs[0].vote_keypair.pubkey();
        let slot_leader = SlotLeader {
            id: node_pubkey,
            vote_address: vote_pubkey,
        };

        let (prev_bank, _bank_forks) = new_bank_for_tests(slot_leader, &genesis_config);
        let current_slot = prev_bank
            .epoch_schedule
            .get_first_slot_in_epoch(prev_bank.epoch() + 1)
            + NUM_SLOTS_FOR_REWARD;

        let bank = new_bank_from_parent(prev_bank.clone(), current_slot);
        let reward_slot = current_slot - NUM_SLOTS_FOR_REWARD;

        calc_vote_rewards_update_vote_states(
            &bank,
            Some(ValidatedRewardCert::new_for_tests(
                reward_slot,
                vec![vote_pubkey],
            )),
            None,
        )
        .unwrap();
        let vote_accounts = bank.vote_accounts();
        for (add, (_, vote_account)) in vote_accounts.iter() {
            let vote_state = vote_state_from_account(vote_account.account());
            if add == &vote_pubkey {
                assert!(!vote_state.epoch_credits().is_empty());
            } else {
                assert!(vote_state.epoch_credits().is_empty());
            }
        }
    }
}