//! Vote state, vote program
//! Receive and processes votes from validators
use {
    crate::{authorized_voters::AuthorizedVoters, id, vote_instruction::VoteError},
    bincode::{deserialize, serialize_into, serialized_size, ErrorKind},
    log::*,
    serde_derive::{Deserialize, Serialize},
    solana_sdk::{
        account::{AccountSharedData, ReadableAccount, WritableAccount},
        account_utils::State,
        clock::{Epoch, Slot, UnixTimestamp},
        epoch_schedule::MAX_LEADER_SCHEDULE_EPOCH_OFFSET,
        hash::Hash,
        instruction::InstructionError,
        keyed_account::KeyedAccount,
        pubkey::Pubkey,
        rent::Rent,
        slot_hashes::SlotHash,
        sysvar::clock::Clock,
    },
    std::{
        boxed::Box,
        cmp::Ordering,
        collections::{HashSet, VecDeque},
    },
};

mod vote_state_0_23_5;
pub mod vote_state_versions;
pub use vote_state_versions::*;

// Maximum number of votes to keep around, tightly coupled with epoch_schedule::MIN_SLOTS_PER_EPOCH
pub const MAX_LOCKOUT_HISTORY: usize = 31;
pub const INITIAL_LOCKOUT: usize = 2;

// Maximum number of credits history to keep around
pub const MAX_EPOCH_CREDITS_HISTORY: usize = 64;

// Offset of VoteState::prior_voters, for determining initialization status without deserialization
const DEFAULT_PRIOR_VOTERS_OFFSET: usize = 82;

#[frozen_abi(digest = "Ch2vVEwos2EjAVqSHCyJjnN2MNX1yrpapZTGhMSCjWUH")]
#[derive(Serialize, Default, Deserialize, Debug, PartialEq, Eq, Clone, AbiExample)]
pub struct Vote {
    /// A stack of votes starting with the oldest vote
    pub slots: Vec<Slot>,
    /// signature of the bank's state at the last slot
    pub hash: Hash,
    /// processing timestamp of last slot
    pub timestamp: Option<UnixTimestamp>,
}

impl Vote {
    pub fn new(slots: Vec<Slot>, hash: Hash) -> Self {
        Self {
            slots,
            hash,
            timestamp: None,
        }
    }

    pub fn last_voted_slot(&self) -> Option<Slot> {
        self.slots.last().copied()
    }

    pub fn last_voted_slot_hash(&self) -> Option<(Slot, Hash)> {
        self.slots.last().copied().map(|slot| (slot, self.hash))
    }
}

#[derive(Serialize, Default, Deserialize, Debug, PartialEq, Eq, Clone, AbiExample)]
pub struct Lockout {
    pub slot: Slot,
    pub confirmation_count: u32,
}

impl Lockout {
    pub fn new(slot: Slot) -> Self {
        Self {
            slot,
            confirmation_count: 1,
        }
    }

    // The number of slots for which this vote is locked
    pub fn lockout(&self) -> u64 {
        (INITIAL_LOCKOUT as u64).pow(self.confirmation_count)
    }

    // The last slot at which a vote is still locked out. Validators should not
    // vote on a slot in another fork which is less than or equal to this slot
    // to avoid having their stake slashed.
    pub fn last_locked_out_slot(&self) -> Slot {
        self.slot + self.lockout()
    }

    pub fn is_locked_out_at_slot(&self, slot: Slot) -> bool {
        self.last_locked_out_slot() >= slot
    }
}

#[derive(Default, Serialize, Deserialize, Debug, PartialEq, Eq, Clone, Copy)]
pub struct VoteInit {
    pub node_pubkey: Pubkey,
    pub authorized_voter: Pubkey,
    pub authorized_withdrawer: Pubkey,
    pub commission: u8,
}

#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone, Copy)]
pub enum VoteAuthorize {
    Voter,
    Withdrawer,
}

#[derive(Debug, Default, Serialize, Deserialize, PartialEq, Eq, Clone, AbiExample)]
pub struct BlockTimestamp {
    pub slot: Slot,
    pub timestamp: UnixTimestamp,
}

// this is how many epochs a voter can be remembered for slashing
const MAX_ITEMS: usize = 32;

#[derive(Debug, Serialize, Deserialize, PartialEq, Eq, Clone, AbiExample)]
pub struct CircBuf<I> {
    buf: [I; MAX_ITEMS],
    /// next pointer
    idx: usize,
    is_empty: bool,
}

impl<I: Default + Copy> Default for CircBuf<I> {
    fn default() -> Self {
        Self {
            buf: [I::default(); MAX_ITEMS],
            idx: MAX_ITEMS - 1,
            is_empty: true,
        }
    }
}

impl<I> CircBuf<I> {
    pub fn append(&mut self, item: I) {
        // remember prior delegate and when we switched, to support later slashing
        self.idx += 1;
        self.idx %= MAX_ITEMS;

        self.buf[self.idx] = item;
        self.is_empty = false;
    }

    pub fn buf(&self) -> &[I; MAX_ITEMS] {
        &self.buf
    }

    pub fn last(&self) -> Option<&I> {
        if !self.is_empty {
            Some(&self.buf[self.idx])
        } else {
            None
        }
    }
}

#[frozen_abi(digest = "331ZmXrmsUcwbKhzR3C1UEU6uNwZr48ExE54JDKGWA4w")]
#[derive(Debug, Default, Serialize, Deserialize, PartialEq, Eq, Clone, AbiExample)]
pub struct VoteState {
    /// the node that votes in this account
    pub node_pubkey: Pubkey,

    /// the signer for withdrawals
    pub authorized_withdrawer: Pubkey,
    /// percentage (0-100) that represents what part of a rewards
    ///  payout should be given to this VoteAccount
    pub commission: u8,

    pub votes: VecDeque<Lockout>,

    // This usually the last Lockout which was popped from self.votes.
    // However, it can be arbitrary slot, when being used inside Tower
    pub root_slot: Option<Slot>,

    /// the signer for vote transactions
    authorized_voters: AuthorizedVoters,

    /// history of prior authorized voters and the epochs for which
    /// they were set, the bottom end of the range is inclusive,
    /// the top of the range is exclusive
    prior_voters: CircBuf<(Pubkey, Epoch, Epoch)>,

    /// history of how many credits earned by the end of each epoch
    ///  each tuple is (Epoch, credits, prev_credits)
    epoch_credits: Vec<(Epoch, u64, u64)>,

    /// most recent timestamp submitted with a vote
    pub last_timestamp: BlockTimestamp,
}

impl VoteState {
    pub fn new(vote_init: &VoteInit, clock: &Clock) -> Self {
        Self {
            node_pubkey: vote_init.node_pubkey,
            authorized_voters: AuthorizedVoters::new(clock.epoch, vote_init.authorized_voter),
            authorized_withdrawer: vote_init.authorized_withdrawer,
            commission: vote_init.commission,
            ..VoteState::default()
        }
    }

    pub fn get_authorized_voter(&self, epoch: Epoch) -> Option<Pubkey> {
        self.authorized_voters.get_authorized_voter(epoch)
    }

    pub fn authorized_voters(&self) -> &AuthorizedVoters {
        &self.authorized_voters
    }

    pub fn prior_voters(&mut self) -> &CircBuf<(Pubkey, Epoch, Epoch)> {
        &self.prior_voters
    }

    pub fn get_rent_exempt_reserve(rent: &Rent) -> u64 {
        rent.minimum_balance(VoteState::size_of())
    }

    pub fn size_of() -> usize {
        // Upper limit on the size of the Vote State. Equal to
        // size_of(VoteState) when votes.len() is MAX_LOCKOUT_HISTORY
        let vote_state = VoteStateVersions::new_current(Self::get_max_sized_vote_state());
        serialized_size(&vote_state).unwrap() as usize
    }

    // utility function, used by Stakes, tests
    pub fn from<T: ReadableAccount>(account: &T) -> Option<VoteState> {
        Self::deserialize(account.data()).ok()
    }

    // utility function, used by Stakes, tests
    pub fn to<T: WritableAccount>(versioned: &VoteStateVersions, account: &mut T) -> Option<()> {
        Self::serialize(versioned, account.data_as_mut_slice()).ok()
    }

    pub fn deserialize(input: &[u8]) -> Result<Self, InstructionError> {
        deserialize::<VoteStateVersions>(input)
            .map(|versioned| versioned.convert_to_current())
            .map_err(|_| InstructionError::InvalidAccountData)
    }

    pub fn serialize(
        versioned: &VoteStateVersions,
        output: &mut [u8],
    ) -> Result<(), InstructionError> {
        serialize_into(output, versioned).map_err(|err| match *err {
            ErrorKind::SizeLimit => InstructionError::AccountDataTooSmall,
            _ => InstructionError::GenericError,
        })
    }

    pub fn credits_from<T: ReadableAccount>(account: &T) -> Option<u64> {
        Self::from(account).map(|state| state.credits())
    }

    /// returns commission split as (voter_portion, staker_portion, was_split) tuple
    ///
    ///  if commission calculation is 100% one way or other,
    ///   indicate with false for was_split
    pub fn commission_split(&self, on: u64) -> (u64, u64, bool) {
        match self.commission.min(100) {
            0 => (0, on, false),
            100 => (on, 0, false),
            split => {
                let on = u128::from(on);
                // Calculate mine and theirs independently and symmetrically instead of
                // using the remainder of the other to treat them strictly equally.
                // This is also to cancel the rewarding if either of the parties
                // should receive only fractional lamports, resulting in not being rewarded at all.
                // Thus, note that we intentionally discard any residual fractional lamports.
                let mine = on * u128::from(split) / 100u128;
                let theirs = on * u128::from(100 - split) / 100u128;

                (mine as u64, theirs as u64, true)
            }
        }
    }

    fn get_max_sized_vote_state() -> VoteState {
        let mut authorized_voters = AuthorizedVoters::default();
        for i in 0..=MAX_LEADER_SCHEDULE_EPOCH_OFFSET {
            authorized_voters.insert(i, solana_sdk::pubkey::new_rand());
        }

        VoteState {
            votes: VecDeque::from(vec![Lockout::default(); MAX_LOCKOUT_HISTORY]),
            root_slot: Some(std::u64::MAX),
            epoch_credits: vec![(0, 0, 0); MAX_EPOCH_CREDITS_HISTORY],
            authorized_voters,
            ..Self::default()
        }
    }

    fn check_slots_are_valid(
        &self,
        vote: &Vote,
        slot_hashes: &[(Slot, Hash)],
    ) -> Result<(), VoteError> {
        // index into the vote's slots, sarting at the newest
        // known slot
        let mut i = 0;

        // index into the slot_hashes, starting at the oldest known
        // slot hash
        let mut j = slot_hashes.len();

        // Note:
        //
        // 1) `vote.slots` is sorted from oldest/smallest vote to newest/largest
        // vote, due to the way votes are applied to the vote state (newest votes
        // pushed to the back), but `slot_hashes` is sorted smallest to largest.
        //
        // 2) Conversely, `slot_hashes` is sorted from newest/largest vote to
        // the oldest/smallest vote
        while i < vote.slots.len() && j > 0 {
            // 1) increment `i` to find the smallest slot `s` in `vote.slots`
            // where `s` >= `last_voted_slot`
            if self
                .last_voted_slot()
                .map_or(false, |last_voted_slot| vote.slots[i] <= last_voted_slot)
            {
                i += 1;
                continue;
            }

            // 2) Find the hash for this slot `s`.
            if vote.slots[i] != slot_hashes[j - 1].0 {
                // Decrement `j` to find newer slots
                j -= 1;
                continue;
            }

            // 3) Once the hash for `s` is found, bump `s` to the next slot
            // in `vote.slots` and continue.
            i += 1;
            j -= 1;
        }

        if j == slot_hashes.len() {
            // This means we never made it to steps 2) or 3) above, otherwise
            // `j` would have been decremented at least once. This means
            // there are not slots in `vote` greater than `last_voted_slot`
            debug!(
                "{} dropped vote {:?} too old: {:?} ",
                self.node_pubkey, vote, slot_hashes
            );
            return Err(VoteError::VoteTooOld);
        }
        if i != vote.slots.len() {
            // This means there existed some slot for which we couldn't find
            // a matching slot hash in step 2)
            info!(
                "{} dropped vote {:?} failed to match slot:  {:?}",
                self.node_pubkey, vote, slot_hashes,
            );
            inc_new_counter_info!("dropped-vote-slot", 1);
            return Err(VoteError::SlotsMismatch);
        }
        if slot_hashes[j].1 != vote.hash {
            // This means the newest vote in the slot has a match that
            // doesn't match the expected hash for that slot on this
            // fork
            warn!(
                "{} dropped vote {:?} failed to match hash {} {}",
                self.node_pubkey, vote, vote.hash, slot_hashes[j].1
            );
            inc_new_counter_info!("dropped-vote-hash", 1);
            return Err(VoteError::SlotHashMismatch);
        }
        Ok(())
    }

    //`Ensure check_slots_are_valid()` runs on the slots in `new_state`
    // before `process_new_vote_state()` is called

    // This function should guarantee the following about `new_state`:
    //
    // 1) It's well ordered, i.e. the slots are sorted from smallest to largest,
    // and the confirmations sorted from largest to smallest.
    // 2) Confirmations `c` on any vote slot satisfy `0 < c <= MAX_LOCKOUT_HISTORY`
    // 3) Lockouts are not expired by consecutive votes, i.e. for every consecutive
    // `v_i`, `v_{i + 1}` satisfy `v_i.last_locked_out_slot() >= v_{i + 1}`.

    // We also guarantee that compared to the current vote state, `new_state`
    // introduces no rollback. This means:
    //
    // 1) The last slot in `new_state` is always greater than any slot in the
    // current vote state.
    //
    // 2) From 1), this means that for every vote `s` in the current state:
    //    a) If there exists an `s'` in `new_state` where `s.slot == s'.slot`, then
    //    we must guarantee `s.confirmations <= s'.confirmations`
    //
    //    b) If there does not exist any such `s'` in `new_state`, then there exists
    //    some `t` that is the smallest vote in `new_state` where `t.slot > s.slot`.
    //    `t` must have expired/popped off s', so it must be guaranteed that
    //    `s.last_locked_out_slot() < t`.

    // Note these two above checks do not guarantee that the vote state being submitted
    // is a vote state that could have been created by iteratively building a tower
    // by processing one vote at a time. For instance, the tower:
    //
    // { slot 0, confirmations: 31 }
    // { slot 1, confirmations: 30 }
    //
    // is a legal tower that could be submitted on top of a previously empty tower. However,
    // there is no way to create this tower from the iterative process, because slot 1 would
    // have to have at least one other slot on top of it, even if the first 30 votes were all
    // popped off.
    pub fn process_new_vote_state(
        &mut self,
        new_state: VecDeque<Lockout>,
        new_root: Option<Slot>,
        timestamp: Option<i64>,
        epoch: Epoch,
    ) -> Result<(), VoteError> {
        assert!(!new_state.is_empty());
        if new_state.len() > MAX_LOCKOUT_HISTORY {
            return Err(VoteError::TooManyVotes);
        }

        // check_slots_are_valid()` ensures we don't process any states
        // that are older than the current state
        if !self.votes.is_empty() {
            assert!(new_state.back().unwrap().slot > self.votes.back().unwrap().slot);
        }

        match (new_root, self.root_slot) {
            (Some(new_root), Some(current_root)) => {
                if new_root < current_root {
                    return Err(VoteError::RootRollBack);
                }
            }
            (None, Some(_)) => {
                return Err(VoteError::RootRollBack);
            }
            _ => (),
        }

        let mut previous_vote: Option<&Lockout> = None;

        // Check that all the votes in the new proposed state are:
        // 1) Strictly sorted from oldest to newest vote
        // 2) The confirmations are strictly decreasing
        // 3) Not zero confirmation votes
        for vote in &new_state {
            if vote.confirmation_count == 0 {
                return Err(VoteError::ZeroConfirmations);
            } else if vote.confirmation_count > MAX_LOCKOUT_HISTORY as u32 {
                return Err(VoteError::ConfirmationTooLarge);
            } else if let Some(new_root) = new_root {
                if vote.slot <= new_root
                &&
                // This check is necessary because
                // https://github.com/ryoqun/solana/blob/df55bfb46af039cbc597cd60042d49b9d90b5961/core/src/consensus.rs#L120
                // always sets a root for even empty towers, which is then hard unwrapped here
                // https://github.com/ryoqun/solana/blob/df55bfb46af039cbc597cd60042d49b9d90b5961/core/src/consensus.rs#L776
                new_root != Slot::default()
                {
                    return Err(VoteError::SlotSmallerThanRoot);
                }
            }

            if let Some(previous_vote) = previous_vote {
                if previous_vote.slot >= vote.slot {
                    return Err(VoteError::SlotsNotOrdered);
                } else if previous_vote.confirmation_count <= vote.confirmation_count {
                    return Err(VoteError::ConfirmationsNotOrdered);
                } else if vote.slot > previous_vote.last_locked_out_slot() {
                    return Err(VoteError::NewVoteStateLockoutMismatch);
                }
            }
            previous_vote = Some(vote);
        }

        // Find the first vote in the current vote state for a slot greater
        // than the new proposed root
        let mut current_vote_state_index = 0;
        let mut new_vote_state_index = 0;

        for current_vote in &self.votes {
            // Find the first vote in the current vote state for a slot greater
            // than the new proposed root
            if let Some(new_root) = new_root {
                if current_vote.slot <= new_root {
                    current_vote_state_index += 1;
                    continue;
                }
            }

            break;
        }

        // All the votes in our current vote state that are missing from the new vote state
        // must have been expired by later votes. Check that the lockouts match this assumption.
        while current_vote_state_index < self.votes.len() && new_vote_state_index < new_state.len()
        {
            let current_vote = &self.votes[current_vote_state_index];
            let new_vote = &new_state[new_vote_state_index];

            // If the current slot is less than the new proposed slot, then the
            // new slot must have popped off the old slot, so check that the
            // lockouts are corrects.
            match current_vote.slot.cmp(&new_vote.slot) {
                Ordering::Less => {
                    if current_vote.last_locked_out_slot() >= new_vote.slot {
                        return Err(VoteError::LockoutConflict);
                    }
                    current_vote_state_index += 1;
                }
                Ordering::Equal => {
                    // The new vote state should never have less lockout than
                    // the previous vote state for the same slot
                    if new_vote.confirmation_count < current_vote.confirmation_count {
                        return Err(VoteError::ConfirmationRollBack);
                    }

                    current_vote_state_index += 1;
                    new_vote_state_index += 1;
                }
                Ordering::Greater => {
                    new_vote_state_index += 1;
                }
            }
        }

        // `new_vote_state` passed all the checks, finalize the change by rewriting
        // our state.
        if self.root_slot != new_root {
            // TODO to think about: Note, people may be incentivized to set more
            // roots to get more credits, but I think they can already do this...
            self.increment_credits(epoch);
        }
        if let Some(timestamp) = timestamp {
            let last_slot = new_state.back().unwrap().slot;
            self.process_timestamp(last_slot, timestamp)?;
        }
        self.root_slot = new_root;
        self.votes = new_state;
        Ok(())
    }

    pub fn process_vote(
        &mut self,
        vote: &Vote,
        slot_hashes: &[SlotHash],
        epoch: Epoch,
    ) -> Result<(), VoteError> {
        if vote.slots.is_empty() {
            return Err(VoteError::EmptySlots);
        }
        self.check_slots_are_valid(vote, slot_hashes)?;

        vote.slots
            .iter()
            .for_each(|s| self.process_next_vote_slot(*s, epoch));
        Ok(())
    }

    pub fn process_next_vote_slot(&mut self, next_vote_slot: Slot, epoch: Epoch) {
        // Ignore votes for slots earlier than we already have votes for
        if self
            .last_voted_slot()
            .map_or(false, |last_voted_slot| next_vote_slot <= last_voted_slot)
        {
            return;
        }

        let vote = Lockout::new(next_vote_slot);

        self.pop_expired_votes(next_vote_slot);

        // Once the stack is full, pop the oldest lockout and distribute rewards
        if self.votes.len() == MAX_LOCKOUT_HISTORY {
            let vote = self.votes.pop_front().unwrap();
            self.root_slot = Some(vote.slot);

            self.increment_credits(epoch);
        }
        self.votes.push_back(vote);
        self.double_lockouts();
    }

    /// increment credits, record credits for last epoch if new epoch
    pub fn increment_credits(&mut self, epoch: Epoch) {
        // increment credits, record by epoch

        // never seen a credit
        if self.epoch_credits.is_empty() {
            self.epoch_credits.push((epoch, 0, 0));
        } else if epoch != self.epoch_credits.last().unwrap().0 {
            let (_, credits, prev_credits) = *self.epoch_credits.last().unwrap();

            if credits != prev_credits {
                // if credits were earned previous epoch
                // append entry at end of list for the new epoch
                self.epoch_credits.push((epoch, credits, credits));
            } else {
                // else just move the current epoch
                self.epoch_credits.last_mut().unwrap().0 = epoch;
            }

            // Remove too old epoch_credits
            if self.epoch_credits.len() > MAX_EPOCH_CREDITS_HISTORY {
                self.epoch_credits.remove(0);
            }
        }

        self.epoch_credits.last_mut().unwrap().1 += 1;
    }

    /// "unchecked" functions used by tests and Tower
    pub fn process_vote_unchecked(&mut self, vote: &Vote) {
        let slot_hashes: Vec<_> = vote.slots.iter().rev().map(|x| (*x, vote.hash)).collect();
        let _ignored = self.process_vote(vote, &slot_hashes, self.current_epoch());
    }

    #[cfg(test)]
    pub fn process_slot_votes_unchecked(&mut self, slots: &[Slot]) {
        for slot in slots {
            self.process_slot_vote_unchecked(*slot);
        }
    }

    pub fn process_slot_vote_unchecked(&mut self, slot: Slot) {
        self.process_vote_unchecked(&Vote::new(vec![slot], Hash::default()));
    }

    pub fn nth_recent_vote(&self, position: usize) -> Option<&Lockout> {
        if position < self.votes.len() {
            let pos = self.votes.len() - 1 - position;
            self.votes.get(pos)
        } else {
            None
        }
    }

    pub fn last_lockout(&self) -> Option<&Lockout> {
        self.votes.back()
    }

    pub fn last_voted_slot(&self) -> Option<Slot> {
        self.last_lockout().map(|v| v.slot)
    }

    // Upto MAX_LOCKOUT_HISTORY many recent unexpired
    // vote slots pushed onto the stack.
    pub fn tower(&self) -> Vec<Slot> {
        self.votes.iter().map(|v| v.slot).collect()
    }

    fn current_epoch(&self) -> Epoch {
        if self.epoch_credits.is_empty() {
            0
        } else {
            self.epoch_credits.last().unwrap().0
        }
    }

    /// Number of "credits" owed to this account from the mining pool. Submit this
    /// VoteState to the Rewards program to trade credits for lamports.
    pub fn credits(&self) -> u64 {
        if self.epoch_credits.is_empty() {
            0
        } else {
            self.epoch_credits.last().unwrap().1
        }
    }

    /// Number of "credits" owed to this account from the mining pool on a per-epoch basis,
    ///  starting from credits observed.
    /// Each tuple of (Epoch, u64, u64) is read as (epoch, credits, prev_credits), where
    ///   credits for each epoch is credits - prev_credits; while redundant this makes
    ///   calculating rewards over partial epochs nice and simple
    pub fn epoch_credits(&self) -> &Vec<(Epoch, u64, u64)> {
        &self.epoch_credits
    }

    fn set_new_authorized_voter<F>(
        &mut self,
        authorized_pubkey: &Pubkey,
        current_epoch: Epoch,
        target_epoch: Epoch,
        verify: F,
    ) -> Result<(), InstructionError>
    where
        F: Fn(Pubkey) -> Result<(), InstructionError>,
    {
        let epoch_authorized_voter = self.get_and_update_authorized_voter(current_epoch)?;
        verify(epoch_authorized_voter)?;

        // The offset in slots `n` on which the target_epoch
        // (default value `DEFAULT_LEADER_SCHEDULE_SLOT_OFFSET`) is
        // calculated is the number of slots available from the
        // first slot `S` of an epoch in which to set a new voter for
        // the epoch at `S` + `n`
        if self.authorized_voters.contains(target_epoch) {
            return Err(VoteError::TooSoonToReauthorize.into());
        }

        // Get the latest authorized_voter
        let (latest_epoch, latest_authorized_pubkey) = self
            .authorized_voters
            .last()
            .ok_or(InstructionError::InvalidAccountData)?;

        // If we're not setting the same pubkey as authorized pubkey again,
        // then update the list of prior voters to mark the expiration
        // of the old authorized pubkey
        if latest_authorized_pubkey != authorized_pubkey {
            // Update the epoch ranges of authorized pubkeys that will be expired
            let epoch_of_last_authorized_switch =
                self.prior_voters.last().map(|range| range.2).unwrap_or(0);

            // target_epoch must:
            // 1) Be monotonically increasing due to the clock always
            //    moving forward
            // 2) not be equal to latest epoch otherwise this
            //    function would have returned TooSoonToReauthorize error
            //    above
            assert!(target_epoch > *latest_epoch);

            // Commit the new state
            self.prior_voters.append((
                *latest_authorized_pubkey,
                epoch_of_last_authorized_switch,
                target_epoch,
            ));
        }

        self.authorized_voters
            .insert(target_epoch, *authorized_pubkey);

        Ok(())
    }

    fn get_and_update_authorized_voter(
        &mut self,
        current_epoch: Epoch,
    ) -> Result<Pubkey, InstructionError> {
        let pubkey = self
            .authorized_voters
            .get_and_cache_authorized_voter_for_epoch(current_epoch)
            .ok_or(InstructionError::InvalidAccountData)?;
        self.authorized_voters
            .purge_authorized_voters(current_epoch);
        Ok(pubkey)
    }

    // Pop all recent votes that are not locked out at the next vote slot.  This
    // allows validators to switch forks once their votes for another fork have
    // expired. This also allows validators continue voting on recent blocks in
    // the same fork without increasing lockouts.
    fn pop_expired_votes(&mut self, next_vote_slot: Slot) {
        while let Some(vote) = self.last_lockout() {
            if !vote.is_locked_out_at_slot(next_vote_slot) {
                self.votes.pop_back();
            } else {
                break;
            }
        }
    }

    fn double_lockouts(&mut self) {
        let stack_depth = self.votes.len();
        for (i, v) in self.votes.iter_mut().enumerate() {
            // Don't increase the lockout for this vote until we get more confirmations
            // than the max number of confirmations this vote has seen
            if stack_depth > i + v.confirmation_count as usize {
                v.confirmation_count += 1;
            }
        }
    }

    pub fn process_timestamp(
        &mut self,
        slot: Slot,
        timestamp: UnixTimestamp,
    ) -> Result<(), VoteError> {
        if (slot < self.last_timestamp.slot || timestamp < self.last_timestamp.timestamp)
            || (slot == self.last_timestamp.slot
                && BlockTimestamp { slot, timestamp } != self.last_timestamp
                && self.last_timestamp.slot != 0)
        {
            return Err(VoteError::TimestampTooOld);
        }
        self.last_timestamp = BlockTimestamp { slot, timestamp };
        Ok(())
    }

    pub fn is_correct_size_and_initialized(data: &[u8]) -> bool {
        const VERSION_OFFSET: usize = 4;
        data.len() == VoteState::size_of()
            && data[VERSION_OFFSET..VERSION_OFFSET + DEFAULT_PRIOR_VOTERS_OFFSET]
                != [0; DEFAULT_PRIOR_VOTERS_OFFSET]
    }
}

/// Authorize the given pubkey to withdraw or sign votes. This may be called multiple times,
/// but will implicitly withdraw authorization from the previously authorized
/// key
pub fn authorize<S: std::hash::BuildHasher>(
    vote_account: &KeyedAccount,
    authorized: &Pubkey,
    vote_authorize: VoteAuthorize,
    signers: &HashSet<Pubkey, S>,
    clock: &Clock,
) -> Result<(), InstructionError> {
    let mut vote_state: VoteState =
        State::<VoteStateVersions>::state(vote_account)?.convert_to_current();

    // current authorized signer must say "yay"
    match vote_authorize {
        VoteAuthorize::Voter => {
            vote_state.set_new_authorized_voter(
                authorized,
                clock.epoch,
                clock.leader_schedule_epoch + 1,
                |epoch_authorized_voter| verify_authorized_signer(&epoch_authorized_voter, signers),
            )?;
        }
        VoteAuthorize::Withdrawer => {
            verify_authorized_signer(&vote_state.authorized_withdrawer, signers)?;
            vote_state.authorized_withdrawer = *authorized;
        }
    }

    vote_account.set_state(&VoteStateVersions::new_current(vote_state))
}

/// Update the node_pubkey, requires signature of the authorized voter
pub fn update_validator_identity<S: std::hash::BuildHasher>(
    vote_account: &KeyedAccount,
    node_pubkey: &Pubkey,
    signers: &HashSet<Pubkey, S>,
) -> Result<(), InstructionError> {
    let mut vote_state: VoteState =
        State::<VoteStateVersions>::state(vote_account)?.convert_to_current();

    // current authorized withdrawer must say "yay"
    verify_authorized_signer(&vote_state.authorized_withdrawer, signers)?;

    // new node must say "yay"
    verify_authorized_signer(node_pubkey, signers)?;

    vote_state.node_pubkey = *node_pubkey;

    vote_account.set_state(&VoteStateVersions::new_current(vote_state))
}

/// Update the vote account's commission
pub fn update_commission<S: std::hash::BuildHasher>(
    vote_account: &KeyedAccount,
    commission: u8,
    signers: &HashSet<Pubkey, S>,
) -> Result<(), InstructionError> {
    let mut vote_state: VoteState =
        State::<VoteStateVersions>::state(vote_account)?.convert_to_current();

    // current authorized withdrawer must say "yay"
    verify_authorized_signer(&vote_state.authorized_withdrawer, signers)?;

    vote_state.commission = commission;

    vote_account.set_state(&VoteStateVersions::new_current(vote_state))
}

fn verify_authorized_signer<S: std::hash::BuildHasher>(
    authorized: &Pubkey,
    signers: &HashSet<Pubkey, S>,
) -> Result<(), InstructionError> {
    if signers.contains(authorized) {
        Ok(())
    } else {
        Err(InstructionError::MissingRequiredSignature)
    }
}

/// Withdraw funds from the vote account
pub fn withdraw<S: std::hash::BuildHasher>(
    vote_account: &KeyedAccount,
    lamports: u64,
    to_account: &KeyedAccount,
    signers: &HashSet<Pubkey, S>,
    rent_sysvar: Option<Rent>,
) -> Result<(), InstructionError> {
    let vote_state: VoteState =
        State::<VoteStateVersions>::state(vote_account)?.convert_to_current();

    verify_authorized_signer(&vote_state.authorized_withdrawer, signers)?;

    let remaining_balance = vote_account
        .lamports()?
        .checked_sub(lamports)
        .ok_or(InstructionError::InsufficientFunds)?;

    if remaining_balance == 0 {
        // Deinitialize upon zero-balance
        vote_account.set_state(&VoteStateVersions::new_current(VoteState::default()))?;
    } else if let Some(rent_sysvar) = rent_sysvar {
        let min_rent_exempt_balance = rent_sysvar.minimum_balance(vote_account.data_len()?);
        if remaining_balance < min_rent_exempt_balance {
            return Err(InstructionError::InsufficientFunds);
        }
    }

    vote_account
        .try_account_ref_mut()?
        .checked_sub_lamports(lamports)?;
    to_account
        .try_account_ref_mut()?
        .checked_add_lamports(lamports)?;
    Ok(())
}

/// Initialize the vote_state for a vote account
/// Assumes that the account is being init as part of a account creation or balance transfer and
/// that the transaction must be signed by the staker's keys
pub fn initialize_account<S: std::hash::BuildHasher>(
    vote_account: &KeyedAccount,
    vote_init: &VoteInit,
    signers: &HashSet<Pubkey, S>,
    clock: &Clock,
) -> Result<(), InstructionError> {
    if vote_account.data_len()? != VoteState::size_of() {
        return Err(InstructionError::InvalidAccountData);
    }
    let versioned = State::<VoteStateVersions>::state(vote_account)?;

    if !versioned.is_uninitialized() {
        return Err(InstructionError::AccountAlreadyInitialized);
    }

    // node must agree to accept this vote account
    verify_authorized_signer(&vote_init.node_pubkey, signers)?;

    vote_account.set_state(&VoteStateVersions::new_current(VoteState::new(
        vote_init, clock,
    )))
}

pub fn process_vote<S: std::hash::BuildHasher>(
    vote_account: &KeyedAccount,
    slot_hashes: &[SlotHash],
    clock: &Clock,
    vote: &Vote,
    signers: &HashSet<Pubkey, S>,
) -> Result<(), InstructionError> {
    let versioned = State::<VoteStateVersions>::state(vote_account)?;

    if versioned.is_uninitialized() {
        return Err(InstructionError::UninitializedAccount);
    }

    let mut vote_state = versioned.convert_to_current();
    let authorized_voter = vote_state.get_and_update_authorized_voter(clock.epoch)?;
    verify_authorized_signer(&authorized_voter, signers)?;

    vote_state.process_vote(vote, slot_hashes, clock.epoch)?;
    if let Some(timestamp) = vote.timestamp {
        vote.slots
            .iter()
            .max()
            .ok_or(VoteError::EmptySlots)
            .and_then(|slot| vote_state.process_timestamp(*slot, timestamp))?;
    }
    vote_account.set_state(&VoteStateVersions::new_current(vote_state))
}

pub fn create_account_with_authorized(
    node_pubkey: &Pubkey,
    authorized_voter: &Pubkey,
    authorized_withdrawer: &Pubkey,
    commission: u8,
    lamports: u64,
) -> AccountSharedData {
    let mut vote_account = AccountSharedData::new(lamports, VoteState::size_of(), &id());

    let vote_state = VoteState::new(
        &VoteInit {
            node_pubkey: *node_pubkey,
            authorized_voter: *authorized_voter,
            authorized_withdrawer: *authorized_withdrawer,
            commission,
        },
        &Clock::default(),
    );

    let versioned = VoteStateVersions::new_current(vote_state);
    VoteState::to(&versioned, &mut vote_account).unwrap();

    vote_account
}

// create_account() should be removed, use create_account_with_authorized() instead
pub fn create_account(
    vote_pubkey: &Pubkey,
    node_pubkey: &Pubkey,
    commission: u8,
    lamports: u64,
) -> AccountSharedData {
    create_account_with_authorized(node_pubkey, vote_pubkey, vote_pubkey, commission, lamports)
}

#[cfg(test)]
mod tests {
    use {
        super::*,
        crate::vote_state,
        solana_sdk::{
            account::AccountSharedData,
            account_utils::StateMut,
            hash::hash,
            keyed_account::{get_signers, keyed_account_at_index},
        },
        std::cell::RefCell,
    };

    const MAX_RECENT_VOTES: usize = 16;

    impl VoteState {
        pub fn new_for_test(auth_pubkey: &Pubkey) -> Self {
            Self::new(
                &VoteInit {
                    node_pubkey: solana_sdk::pubkey::new_rand(),
                    authorized_voter: *auth_pubkey,
                    authorized_withdrawer: *auth_pubkey,
                    commission: 0,
                },
                &Clock::default(),
            )
        }
    }

    #[test]
    fn test_initialize_vote_account() {
        let vote_account_pubkey = solana_sdk::pubkey::new_rand();
        let vote_account = AccountSharedData::new_ref(100, VoteState::size_of(), &id());
        let vote_account = KeyedAccount::new(&vote_account_pubkey, false, &vote_account);

        let node_pubkey = solana_sdk::pubkey::new_rand();
        let node_account = RefCell::new(AccountSharedData::default());
        let keyed_accounts = &[];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);

        //init should fail, node_pubkey didn't sign the transaction
        let res = initialize_account(
            &vote_account,
            &VoteInit {
                node_pubkey,
                authorized_voter: vote_account_pubkey,
                authorized_withdrawer: vote_account_pubkey,
                commission: 0,
            },
            &signers,
            &Clock::default(),
        );
        assert_eq!(res, Err(InstructionError::MissingRequiredSignature));

        let keyed_accounts = &[KeyedAccount::new(&node_pubkey, true, &node_account)];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);

        //init should pass
        let res = initialize_account(
            &vote_account,
            &VoteInit {
                node_pubkey,
                authorized_voter: vote_account_pubkey,
                authorized_withdrawer: vote_account_pubkey,
                commission: 0,
            },
            &signers,
            &Clock::default(),
        );
        assert_eq!(res, Ok(()));

        // reinit should fail
        let res = initialize_account(
            &vote_account,
            &VoteInit {
                node_pubkey,
                authorized_voter: vote_account_pubkey,
                authorized_withdrawer: vote_account_pubkey,
                commission: 0,
            },
            &signers,
            &Clock::default(),
        );
        assert_eq!(res, Err(InstructionError::AccountAlreadyInitialized));

        //init should fail, account is too big
        let large_vote_account = AccountSharedData::new_ref(100, 2 * VoteState::size_of(), &id());
        let large_vote_account =
            KeyedAccount::new(&vote_account_pubkey, false, &large_vote_account);
        let res = initialize_account(
            &large_vote_account,
            &VoteInit {
                node_pubkey,
                authorized_voter: vote_account_pubkey,
                authorized_withdrawer: vote_account_pubkey,
                commission: 0,
            },
            &signers,
            &Clock::default(),
        );
        assert_eq!(res, Err(InstructionError::InvalidAccountData));
    }

    fn create_test_account() -> (Pubkey, RefCell<AccountSharedData>) {
        let rent = Rent::default();
        let balance = VoteState::get_rent_exempt_reserve(&rent);
        let vote_pubkey = solana_sdk::pubkey::new_rand();
        (
            vote_pubkey,
            RefCell::new(vote_state::create_account(
                &vote_pubkey,
                &solana_sdk::pubkey::new_rand(),
                0,
                balance,
            )),
        )
    }

    fn create_test_account_with_authorized() -> (Pubkey, Pubkey, Pubkey, RefCell<AccountSharedData>)
    {
        let vote_pubkey = solana_sdk::pubkey::new_rand();
        let authorized_voter = solana_sdk::pubkey::new_rand();
        let authorized_withdrawer = solana_sdk::pubkey::new_rand();

        (
            vote_pubkey,
            authorized_voter,
            authorized_withdrawer,
            RefCell::new(vote_state::create_account_with_authorized(
                &solana_sdk::pubkey::new_rand(),
                &authorized_voter,
                &authorized_withdrawer,
                0,
                100,
            )),
        )
    }

    fn simulate_process_vote(
        vote_pubkey: &Pubkey,
        vote_account: &RefCell<AccountSharedData>,
        vote: &Vote,
        slot_hashes: &[SlotHash],
        epoch: Epoch,
    ) -> Result<VoteState, InstructionError> {
        let keyed_accounts = &[KeyedAccount::new(vote_pubkey, true, vote_account)];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        process_vote(
            &keyed_accounts[0],
            slot_hashes,
            &Clock {
                epoch,
                ..Clock::default()
            },
            &vote.clone(),
            &signers,
        )?;
        StateMut::<VoteStateVersions>::state(&*vote_account.borrow())
            .map(|versioned| versioned.convert_to_current())
    }

    /// exercises all the keyed accounts stuff
    fn simulate_process_vote_unchecked(
        vote_pubkey: &Pubkey,
        vote_account: &RefCell<AccountSharedData>,
        vote: &Vote,
    ) -> Result<VoteState, InstructionError> {
        simulate_process_vote(
            vote_pubkey,
            vote_account,
            vote,
            &[(*vote.slots.last().unwrap(), vote.hash)],
            0,
        )
    }

    #[test]
    fn test_vote_serialize() {
        let mut buffer: Vec<u8> = vec![0; VoteState::size_of()];
        let mut vote_state = VoteState::default();
        vote_state
            .votes
            .resize(MAX_LOCKOUT_HISTORY, Lockout::default());
        let versioned = VoteStateVersions::new_current(vote_state);
        assert!(VoteState::serialize(&versioned, &mut buffer[0..4]).is_err());
        VoteState::serialize(&versioned, &mut buffer).unwrap();
        assert_eq!(
            VoteStateVersions::new_current(VoteState::deserialize(&buffer).unwrap()),
            versioned
        );
    }

    #[test]
    fn test_voter_registration() {
        let (vote_pubkey, vote_account) = create_test_account();

        let vote_state: VoteState = StateMut::<VoteStateVersions>::state(&*vote_account.borrow())
            .unwrap()
            .convert_to_current();
        assert_eq!(vote_state.authorized_voters.len(), 1);
        assert_eq!(
            *vote_state.authorized_voters.first().unwrap().1,
            vote_pubkey
        );
        assert!(vote_state.votes.is_empty());
    }

    #[test]
    fn test_vote() {
        let (vote_pubkey, vote_account) = create_test_account();

        let vote = Vote::new(vec![1], Hash::default());
        let vote_state =
            simulate_process_vote_unchecked(&vote_pubkey, &vote_account, &vote).unwrap();
        assert_eq!(
            vote_state.votes,
            vec![Lockout::new(*vote.slots.last().unwrap())]
        );
        assert_eq!(vote_state.credits(), 0);
    }

    #[test]
    fn test_vote_slot_hashes() {
        let (vote_pubkey, vote_account) = create_test_account();

        let hash = hash(&[0u8]);
        let vote = Vote::new(vec![0], hash);

        // wrong hash
        assert_eq!(
            simulate_process_vote(
                &vote_pubkey,
                &vote_account,
                &vote,
                &[(0, Hash::default())],
                0,
            ),
            Err(VoteError::SlotHashMismatch.into())
        );

        // wrong slot
        assert_eq!(
            simulate_process_vote(&vote_pubkey, &vote_account, &vote, &[(1, hash)], 0),
            Err(VoteError::SlotsMismatch.into())
        );

        // empty slot_hashes
        assert_eq!(
            simulate_process_vote(&vote_pubkey, &vote_account, &vote, &[], 0),
            Err(VoteError::VoteTooOld.into())
        );
    }

    #[test]
    fn test_vote_update_validator_identity() {
        let (vote_pubkey, _authorized_voter, authorized_withdrawer, vote_account) =
            create_test_account_with_authorized();

        let node_pubkey = solana_sdk::pubkey::new_rand();
        let node_account = RefCell::new(AccountSharedData::default());
        let authorized_withdrawer_account = RefCell::new(AccountSharedData::default());

        let keyed_accounts = &[
            KeyedAccount::new(&vote_pubkey, true, &vote_account),
            KeyedAccount::new(&node_pubkey, false, &node_account),
            KeyedAccount::new(&authorized_withdrawer, true, &authorized_withdrawer_account),
        ];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = update_validator_identity(&keyed_accounts[0], &node_pubkey, &signers);
        assert_eq!(res, Err(InstructionError::MissingRequiredSignature));

        let keyed_accounts = &[
            KeyedAccount::new(&vote_pubkey, true, &vote_account),
            KeyedAccount::new(&node_pubkey, true, &node_account),
            KeyedAccount::new(
                &authorized_withdrawer,
                false,
                &authorized_withdrawer_account,
            ),
        ];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = update_validator_identity(&keyed_accounts[0], &node_pubkey, &signers);
        assert_eq!(res, Err(InstructionError::MissingRequiredSignature));
        let vote_state: VoteState = StateMut::<VoteStateVersions>::state(&*vote_account.borrow())
            .unwrap()
            .convert_to_current();
        assert!(vote_state.node_pubkey != node_pubkey);

        let keyed_accounts = &[
            KeyedAccount::new(&vote_pubkey, true, &vote_account),
            KeyedAccount::new(&node_pubkey, true, &node_account),
            KeyedAccount::new(&authorized_withdrawer, true, &authorized_withdrawer_account),
        ];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = update_validator_identity(&keyed_accounts[0], &node_pubkey, &signers);
        assert_eq!(res, Ok(()));
        let vote_state: VoteState = StateMut::<VoteStateVersions>::state(&*vote_account.borrow())
            .unwrap()
            .convert_to_current();
        assert_eq!(vote_state.node_pubkey, node_pubkey);
    }

    #[test]
    fn test_vote_update_commission() {
        let (vote_pubkey, _authorized_voter, authorized_withdrawer, vote_account) =
            create_test_account_with_authorized();

        let authorized_withdrawer_account = RefCell::new(AccountSharedData::default());

        let keyed_accounts = &[
            KeyedAccount::new(&vote_pubkey, true, &vote_account),
            KeyedAccount::new(
                &authorized_withdrawer,
                false,
                &authorized_withdrawer_account,
            ),
        ];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = update_commission(&keyed_accounts[0], 42, &signers);
        assert_eq!(res, Err(InstructionError::MissingRequiredSignature));

        let keyed_accounts = &[
            KeyedAccount::new(&vote_pubkey, true, &vote_account),
            KeyedAccount::new(&authorized_withdrawer, true, &authorized_withdrawer_account),
        ];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = update_commission(&keyed_accounts[0], 42, &signers);
        assert_eq!(res, Ok(()));
        let vote_state: VoteState = StateMut::<VoteStateVersions>::state(&*vote_account.borrow())
            .unwrap()
            .convert_to_current();
        assert_eq!(vote_state.commission, 42);

        let keyed_accounts = &[
            KeyedAccount::new(&vote_pubkey, true, &vote_account),
            KeyedAccount::new(&authorized_withdrawer, true, &authorized_withdrawer_account),
        ];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = update_commission(&keyed_accounts[0], u8::MAX, &signers);
        assert_eq!(res, Ok(()));
        let vote_state: VoteState = StateMut::<VoteStateVersions>::state(&*vote_account.borrow())
            .unwrap()
            .convert_to_current();
        assert_eq!(vote_state.commission, u8::MAX);
    }

    #[test]
    fn test_vote_signature() {
        let (vote_pubkey, vote_account) = create_test_account();
        let vote = Vote::new(vec![1], Hash::default());

        // unsigned
        let keyed_accounts = &[KeyedAccount::new(&vote_pubkey, false, &vote_account)];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = process_vote(
            &keyed_accounts[0],
            &[(*vote.slots.last().unwrap(), vote.hash)],
            &Clock {
                epoch: 1,
                leader_schedule_epoch: 2,
                ..Clock::default()
            },
            &vote,
            &signers,
        );
        assert_eq!(res, Err(InstructionError::MissingRequiredSignature));

        // signed
        let keyed_accounts = &[KeyedAccount::new(&vote_pubkey, true, &vote_account)];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = process_vote(
            &keyed_accounts[0],
            &[(*vote.slots.last().unwrap(), vote.hash)],
            &Clock {
                epoch: 1,
                leader_schedule_epoch: 2,
                ..Clock::default()
            },
            &vote,
            &signers,
        );
        assert_eq!(res, Ok(()));

        // another voter, unsigned
        let keyed_accounts = &[KeyedAccount::new(&vote_pubkey, false, &vote_account)];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let authorized_voter_pubkey = solana_sdk::pubkey::new_rand();
        let res = authorize(
            &keyed_accounts[0],
            &authorized_voter_pubkey,
            VoteAuthorize::Voter,
            &signers,
            &Clock {
                epoch: 1,
                leader_schedule_epoch: 2,
                ..Clock::default()
            },
        );
        assert_eq!(res, Err(InstructionError::MissingRequiredSignature));

        let keyed_accounts = &[KeyedAccount::new(&vote_pubkey, true, &vote_account)];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = authorize(
            &keyed_accounts[0],
            &authorized_voter_pubkey,
            VoteAuthorize::Voter,
            &signers,
            &Clock {
                epoch: 1,
                leader_schedule_epoch: 2,
                ..Clock::default()
            },
        );
        assert_eq!(res, Ok(()));

        // Already set an authorized voter earlier for leader_schedule_epoch == 2
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = authorize(
            &keyed_accounts[0],
            &authorized_voter_pubkey,
            VoteAuthorize::Voter,
            &signers,
            &Clock {
                epoch: 1,
                leader_schedule_epoch: 2,
                ..Clock::default()
            },
        );
        assert_eq!(res, Err(VoteError::TooSoonToReauthorize.into()));

        // verify authorized_voter_pubkey can authorize authorized_voter_pubkey ;)
        let authorized_voter_account = RefCell::new(AccountSharedData::default());
        let keyed_accounts = &[
            KeyedAccount::new(&vote_pubkey, false, &vote_account),
            KeyedAccount::new(&authorized_voter_pubkey, true, &authorized_voter_account),
        ];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = authorize(
            &keyed_accounts[0],
            &authorized_voter_pubkey,
            VoteAuthorize::Voter,
            &signers,
            &Clock {
                // The authorized voter was set when leader_schedule_epoch == 2, so will
                // take effect when epoch == 3
                epoch: 3,
                leader_schedule_epoch: 4,
                ..Clock::default()
            },
        );
        assert_eq!(res, Ok(()));

        // authorize another withdrawer
        // another voter
        let keyed_accounts = &[KeyedAccount::new(&vote_pubkey, true, &vote_account)];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let authorized_withdrawer_pubkey = solana_sdk::pubkey::new_rand();
        let res = authorize(
            &keyed_accounts[0],
            &authorized_withdrawer_pubkey,
            VoteAuthorize::Withdrawer,
            &signers,
            &Clock {
                epoch: 3,
                leader_schedule_epoch: 4,
                ..Clock::default()
            },
        );
        assert_eq!(res, Ok(()));

        // verify authorized_withdrawer can authorize authorized_withdrawer ;)
        let withdrawer_account = RefCell::new(AccountSharedData::default());
        let keyed_accounts = &[
            KeyedAccount::new(&vote_pubkey, false, &vote_account),
            KeyedAccount::new(&authorized_withdrawer_pubkey, true, &withdrawer_account),
        ];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = authorize(
            &keyed_accounts[0],
            &authorized_withdrawer_pubkey,
            VoteAuthorize::Withdrawer,
            &signers,
            &Clock {
                epoch: 3,
                leader_schedule_epoch: 4,
                ..Clock::default()
            },
        );
        assert_eq!(res, Ok(()));

        // not signed by authorized voter
        let keyed_accounts = &[KeyedAccount::new(&vote_pubkey, true, &vote_account)];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let vote = Vote::new(vec![2], Hash::default());
        let res = process_vote(
            &keyed_accounts[0],
            &[(*vote.slots.last().unwrap(), vote.hash)],
            &Clock {
                epoch: 3,
                leader_schedule_epoch: 4,
                ..Clock::default()
            },
            &vote,
            &signers,
        );
        assert_eq!(res, Err(InstructionError::MissingRequiredSignature));

        // signed by authorized voter
        let authorized_voter_account = RefCell::new(AccountSharedData::default());
        let keyed_accounts = &[
            KeyedAccount::new(&vote_pubkey, false, &vote_account),
            KeyedAccount::new(&authorized_voter_pubkey, true, &authorized_voter_account),
        ];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let vote = Vote::new(vec![2], Hash::default());
        let res = process_vote(
            &keyed_accounts[0],
            &[(*vote.slots.last().unwrap(), vote.hash)],
            &Clock {
                epoch: 3,
                leader_schedule_epoch: 4,
                ..Clock::default()
            },
            &vote,
            &signers,
        );
        assert_eq!(res, Ok(()));
    }

    #[test]
    fn test_vote_without_initialization() {
        let vote_pubkey = solana_sdk::pubkey::new_rand();
        let vote_account = RefCell::new(AccountSharedData::new(100, VoteState::size_of(), &id()));

        let res = simulate_process_vote_unchecked(
            &vote_pubkey,
            &vote_account,
            &Vote::new(vec![1], Hash::default()),
        );
        assert_eq!(res, Err(InstructionError::UninitializedAccount));
    }

    #[test]
    fn test_vote_lockout() {
        let (_vote_pubkey, vote_account) = create_test_account();

        let mut vote_state: VoteState =
            StateMut::<VoteStateVersions>::state(&*vote_account.borrow())
                .unwrap()
                .convert_to_current();

        for i in 0..(MAX_LOCKOUT_HISTORY + 1) {
            vote_state.process_slot_vote_unchecked((INITIAL_LOCKOUT as usize * i) as u64);
        }

        // The last vote should have been popped b/c it reached a depth of MAX_LOCKOUT_HISTORY
        assert_eq!(vote_state.votes.len(), MAX_LOCKOUT_HISTORY);
        assert_eq!(vote_state.root_slot, Some(0));
        check_lockouts(&vote_state);

        // One more vote that confirms the entire stack,
        // the root_slot should change to the
        // second vote
        let top_vote = vote_state.votes.front().unwrap().slot;
        vote_state
            .process_slot_vote_unchecked(vote_state.last_lockout().unwrap().last_locked_out_slot());
        assert_eq!(Some(top_vote), vote_state.root_slot);

        // Expire everything except the first vote
        vote_state
            .process_slot_vote_unchecked(vote_state.votes.front().unwrap().last_locked_out_slot());
        // First vote and new vote are both stored for a total of 2 votes
        assert_eq!(vote_state.votes.len(), 2);
    }

    #[test]
    fn test_vote_double_lockout_after_expiration() {
        let voter_pubkey = solana_sdk::pubkey::new_rand();
        let mut vote_state = VoteState::new_for_test(&voter_pubkey);

        for i in 0..3 {
            vote_state.process_slot_vote_unchecked(i as u64);
        }

        check_lockouts(&vote_state);

        // Expire the third vote (which was a vote for slot 2). The height of the
        // vote stack is unchanged, so none of the previous votes should have
        // doubled in lockout
        vote_state.process_slot_vote_unchecked((2 + INITIAL_LOCKOUT + 1) as u64);
        check_lockouts(&vote_state);

        // Vote again, this time the vote stack depth increases, so the votes should
        // double for everybody
        vote_state.process_slot_vote_unchecked((2 + INITIAL_LOCKOUT + 2) as u64);
        check_lockouts(&vote_state);

        // Vote again, this time the vote stack depth increases, so the votes should
        // double for everybody
        vote_state.process_slot_vote_unchecked((2 + INITIAL_LOCKOUT + 3) as u64);
        check_lockouts(&vote_state);
    }

    #[test]
    fn test_expire_multiple_votes() {
        let voter_pubkey = solana_sdk::pubkey::new_rand();
        let mut vote_state = VoteState::new_for_test(&voter_pubkey);

        for i in 0..3 {
            vote_state.process_slot_vote_unchecked(i as u64);
        }

        assert_eq!(vote_state.votes[0].confirmation_count, 3);

        // Expire the second and third votes
        let expire_slot = vote_state.votes[1].slot + vote_state.votes[1].lockout() + 1;
        vote_state.process_slot_vote_unchecked(expire_slot);
        assert_eq!(vote_state.votes.len(), 2);

        // Check that the old votes expired
        assert_eq!(vote_state.votes[0].slot, 0);
        assert_eq!(vote_state.votes[1].slot, expire_slot);

        // Process one more vote
        vote_state.process_slot_vote_unchecked(expire_slot + 1);

        // Confirmation count for the older first vote should remain unchanged
        assert_eq!(vote_state.votes[0].confirmation_count, 3);

        // The later votes should still have increasing confirmation counts
        assert_eq!(vote_state.votes[1].confirmation_count, 2);
        assert_eq!(vote_state.votes[2].confirmation_count, 1);
    }

    #[test]
    fn test_vote_credits() {
        let voter_pubkey = solana_sdk::pubkey::new_rand();
        let mut vote_state = VoteState::new_for_test(&voter_pubkey);

        for i in 0..MAX_LOCKOUT_HISTORY {
            vote_state.process_slot_vote_unchecked(i as u64);
        }

        assert_eq!(vote_state.credits(), 0);

        vote_state.process_slot_vote_unchecked(MAX_LOCKOUT_HISTORY as u64 + 1);
        assert_eq!(vote_state.credits(), 1);
        vote_state.process_slot_vote_unchecked(MAX_LOCKOUT_HISTORY as u64 + 2);
        assert_eq!(vote_state.credits(), 2);
        vote_state.process_slot_vote_unchecked(MAX_LOCKOUT_HISTORY as u64 + 3);
        assert_eq!(vote_state.credits(), 3);
    }

    #[test]
    fn test_duplicate_vote() {
        let voter_pubkey = solana_sdk::pubkey::new_rand();
        let mut vote_state = VoteState::new_for_test(&voter_pubkey);
        vote_state.process_slot_vote_unchecked(0);
        vote_state.process_slot_vote_unchecked(1);
        vote_state.process_slot_vote_unchecked(0);
        assert_eq!(vote_state.nth_recent_vote(0).unwrap().slot, 1);
        assert_eq!(vote_state.nth_recent_vote(1).unwrap().slot, 0);
        assert!(vote_state.nth_recent_vote(2).is_none());
    }

    #[test]
    fn test_nth_recent_vote() {
        let voter_pubkey = solana_sdk::pubkey::new_rand();
        let mut vote_state = VoteState::new_for_test(&voter_pubkey);
        for i in 0..MAX_LOCKOUT_HISTORY {
            vote_state.process_slot_vote_unchecked(i as u64);
        }
        for i in 0..(MAX_LOCKOUT_HISTORY - 1) {
            assert_eq!(
                vote_state.nth_recent_vote(i).unwrap().slot as usize,
                MAX_LOCKOUT_HISTORY - i - 1,
            );
        }
        assert!(vote_state.nth_recent_vote(MAX_LOCKOUT_HISTORY).is_none());
    }

    fn check_lockouts(vote_state: &VoteState) {
        for (i, vote) in vote_state.votes.iter().enumerate() {
            let num_votes = vote_state.votes.len() - i;
            assert_eq!(vote.lockout(), INITIAL_LOCKOUT.pow(num_votes as u32) as u64);
        }
    }

    fn recent_votes(vote_state: &VoteState) -> Vec<Vote> {
        let start = vote_state.votes.len().saturating_sub(MAX_RECENT_VOTES);
        (start..vote_state.votes.len())
            .map(|i| Vote::new(vec![vote_state.votes.get(i).unwrap().slot], Hash::default()))
            .collect()
    }

    /// check that two accounts with different data can be brought to the same state with one vote submission
    #[test]
    fn test_process_missed_votes() {
        let account_a = solana_sdk::pubkey::new_rand();
        let mut vote_state_a = VoteState::new_for_test(&account_a);
        let account_b = solana_sdk::pubkey::new_rand();
        let mut vote_state_b = VoteState::new_for_test(&account_b);

        // process some votes on account a
        (0..5).for_each(|i| vote_state_a.process_slot_vote_unchecked(i as u64));
        assert_ne!(recent_votes(&vote_state_a), recent_votes(&vote_state_b));

        // as long as b has missed less than "NUM_RECENT" votes both accounts should be in sync
        let slots = (0u64..MAX_RECENT_VOTES as u64).collect();
        let vote = Vote::new(slots, Hash::default());
        let slot_hashes: Vec<_> = vote.slots.iter().rev().map(|x| (*x, vote.hash)).collect();

        assert_eq!(vote_state_a.process_vote(&vote, &slot_hashes, 0), Ok(()));
        assert_eq!(vote_state_b.process_vote(&vote, &slot_hashes, 0), Ok(()));
        assert_eq!(recent_votes(&vote_state_a), recent_votes(&vote_state_b));
    }

    #[test]
    fn test_process_vote_skips_old_vote() {
        let mut vote_state = VoteState::default();

        let vote = Vote::new(vec![0], Hash::default());
        let slot_hashes: Vec<_> = vec![(0, vote.hash)];
        assert_eq!(vote_state.process_vote(&vote, &slot_hashes, 0), Ok(()));
        let recent = recent_votes(&vote_state);
        assert_eq!(
            vote_state.process_vote(&vote, &slot_hashes, 0),
            Err(VoteError::VoteTooOld)
        );
        assert_eq!(recent, recent_votes(&vote_state));
    }

    #[test]
    fn test_check_slots_are_valid_vote_empty_slot_hashes() {
        let vote_state = VoteState::default();

        let vote = Vote::new(vec![0], Hash::default());
        assert_eq!(
            vote_state.check_slots_are_valid(&vote, &[]),
            Err(VoteError::VoteTooOld)
        );
    }

    #[test]
    fn test_check_slots_are_valid_new_vote() {
        let vote_state = VoteState::default();

        let vote = Vote::new(vec![0], Hash::default());
        let slot_hashes: Vec<_> = vec![(*vote.slots.last().unwrap(), vote.hash)];
        assert_eq!(
            vote_state.check_slots_are_valid(&vote, &slot_hashes),
            Ok(())
        );
    }

    #[test]
    fn test_check_slots_are_valid_bad_hash() {
        let vote_state = VoteState::default();

        let vote = Vote::new(vec![0], Hash::default());
        let slot_hashes: Vec<_> = vec![(*vote.slots.last().unwrap(), hash(vote.hash.as_ref()))];
        assert_eq!(
            vote_state.check_slots_are_valid(&vote, &slot_hashes),
            Err(VoteError::SlotHashMismatch)
        );
    }

    #[test]
    fn test_check_slots_are_valid_bad_slot() {
        let vote_state = VoteState::default();

        let vote = Vote::new(vec![1], Hash::default());
        let slot_hashes: Vec<_> = vec![(0, vote.hash)];
        assert_eq!(
            vote_state.check_slots_are_valid(&vote, &slot_hashes),
            Err(VoteError::SlotsMismatch)
        );
    }

    #[test]
    fn test_check_slots_are_valid_duplicate_vote() {
        let mut vote_state = VoteState::default();

        let vote = Vote::new(vec![0], Hash::default());
        let slot_hashes: Vec<_> = vec![(*vote.slots.last().unwrap(), vote.hash)];
        assert_eq!(vote_state.process_vote(&vote, &slot_hashes, 0), Ok(()));
        assert_eq!(
            vote_state.check_slots_are_valid(&vote, &slot_hashes),
            Err(VoteError::VoteTooOld)
        );
    }

    #[test]
    fn test_check_slots_are_valid_next_vote() {
        let mut vote_state = VoteState::default();

        let vote = Vote::new(vec![0], Hash::default());
        let slot_hashes: Vec<_> = vec![(*vote.slots.last().unwrap(), vote.hash)];
        assert_eq!(vote_state.process_vote(&vote, &slot_hashes, 0), Ok(()));

        let vote = Vote::new(vec![0, 1], Hash::default());
        let slot_hashes: Vec<_> = vec![(1, vote.hash), (0, vote.hash)];
        assert_eq!(
            vote_state.check_slots_are_valid(&vote, &slot_hashes),
            Ok(())
        );
    }

    #[test]
    fn test_check_slots_are_valid_next_vote_only() {
        let mut vote_state = VoteState::default();

        let vote = Vote::new(vec![0], Hash::default());
        let slot_hashes: Vec<_> = vec![(*vote.slots.last().unwrap(), vote.hash)];
        assert_eq!(vote_state.process_vote(&vote, &slot_hashes, 0), Ok(()));

        let vote = Vote::new(vec![1], Hash::default());
        let slot_hashes: Vec<_> = vec![(1, vote.hash), (0, vote.hash)];
        assert_eq!(
            vote_state.check_slots_are_valid(&vote, &slot_hashes),
            Ok(())
        );
    }
    #[test]
    fn test_process_vote_empty_slots() {
        let mut vote_state = VoteState::default();

        let vote = Vote::new(vec![], Hash::default());
        assert_eq!(
            vote_state.process_vote(&vote, &[], 0),
            Err(VoteError::EmptySlots)
        );
    }

    #[test]
    fn test_vote_state_commission_split() {
        let vote_state = VoteState::default();

        assert_eq!(vote_state.commission_split(1), (0, 1, false));

        let mut vote_state = VoteState {
            commission: std::u8::MAX,
            ..VoteState::default()
        };
        assert_eq!(vote_state.commission_split(1), (1, 0, false));

        vote_state.commission = 99;
        assert_eq!(vote_state.commission_split(10), (9, 0, true));

        vote_state.commission = 1;
        assert_eq!(vote_state.commission_split(10), (0, 9, true));

        vote_state.commission = 50;
        let (voter_portion, staker_portion, was_split) = vote_state.commission_split(10);

        assert_eq!((voter_portion, staker_portion, was_split), (5, 5, true));
    }

    #[test]
    fn test_vote_state_withdraw() {
        let (vote_pubkey, vote_account) = create_test_account();

        // unsigned request
        let keyed_accounts = &[KeyedAccount::new(&vote_pubkey, false, &vote_account)];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = withdraw(
            &keyed_accounts[0],
            0,
            &KeyedAccount::new(
                &solana_sdk::pubkey::new_rand(),
                false,
                &RefCell::new(AccountSharedData::default()),
            ),
            &signers,
            None,
        );
        assert_eq!(res, Err(InstructionError::MissingRequiredSignature));

        // insufficient funds
        let keyed_accounts = &[KeyedAccount::new(&vote_pubkey, true, &vote_account)];
        let lamports = vote_account.borrow().lamports();
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = withdraw(
            &keyed_accounts[0],
            lamports + 1,
            &KeyedAccount::new(
                &solana_sdk::pubkey::new_rand(),
                false,
                &RefCell::new(AccountSharedData::default()),
            ),
            &signers,
            None,
        );
        assert_eq!(res, Err(InstructionError::InsufficientFunds));

        // non rent exempt withdraw, before feature activation
        {
            let (vote_pubkey, vote_account) = create_test_account();
            let keyed_accounts = &[KeyedAccount::new(&vote_pubkey, true, &vote_account)];
            let lamports = vote_account.borrow().lamports();
            let rent_sysvar = Rent::default();
            let minimum_balance = rent_sysvar
                .minimum_balance(vote_account.borrow().data().len())
                .max(1);
            assert!(minimum_balance <= lamports);
            let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
            let res = withdraw(
                &keyed_accounts[0],
                lamports - minimum_balance + 1,
                &KeyedAccount::new(
                    &solana_sdk::pubkey::new_rand(),
                    false,
                    &RefCell::new(AccountSharedData::default()),
                ),
                &signers,
                None,
            );
            assert_eq!(res, Ok(()));
        }

        // non rent exempt withdraw, after feature activation
        {
            let (vote_pubkey, vote_account) = create_test_account();
            let keyed_accounts = &[KeyedAccount::new(&vote_pubkey, true, &vote_account)];
            let lamports = vote_account.borrow().lamports();
            let rent_sysvar = Rent::default();
            let minimum_balance = rent_sysvar
                .minimum_balance(vote_account.borrow().data().len())
                .max(1);
            assert!(minimum_balance <= lamports);
            let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
            let res = withdraw(
                &keyed_accounts[0],
                lamports - minimum_balance + 1,
                &KeyedAccount::new(
                    &solana_sdk::pubkey::new_rand(),
                    false,
                    &RefCell::new(AccountSharedData::default()),
                ),
                &signers,
                Some(rent_sysvar),
            );
            assert_eq!(res, Err(InstructionError::InsufficientFunds));
        }

        // partial valid withdraw, after feature activation
        {
            let to_account = RefCell::new(AccountSharedData::default());
            let (vote_pubkey, vote_account) = create_test_account();
            let keyed_accounts = &[KeyedAccount::new(&vote_pubkey, true, &vote_account)];
            let lamports = vote_account.borrow().lamports();
            let rent_sysvar = Rent::default();
            let minimum_balance = rent_sysvar
                .minimum_balance(vote_account.borrow().data().len())
                .max(1);
            assert!(minimum_balance <= lamports);
            let withdraw_lamports = lamports - minimum_balance;
            let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
            let res = withdraw(
                &keyed_accounts[0],
                withdraw_lamports,
                &KeyedAccount::new(&solana_sdk::pubkey::new_rand(), false, &to_account),
                &signers,
                Some(rent_sysvar),
            );
            assert_eq!(res, Ok(()));
            assert_eq!(
                vote_account.borrow().lamports(),
                lamports - withdraw_lamports
            );
            assert_eq!(to_account.borrow().lamports(), withdraw_lamports);
        }

        // full withdraw, before/after activation
        {
            let rent_sysvar = Rent::default();
            for rent_sysvar in [None, Some(rent_sysvar)] {
                let to_account = RefCell::new(AccountSharedData::default());
                let (vote_pubkey, vote_account) = create_test_account();
                let lamports = vote_account.borrow().lamports();
                let keyed_accounts = &[KeyedAccount::new(&vote_pubkey, true, &vote_account)];
                let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
                let res = withdraw(
                    &keyed_accounts[0],
                    lamports,
                    &KeyedAccount::new(&solana_sdk::pubkey::new_rand(), false, &to_account),
                    &signers,
                    rent_sysvar,
                );
                assert_eq!(res, Ok(()));
                assert_eq!(vote_account.borrow().lamports(), 0);
                assert_eq!(to_account.borrow().lamports(), lamports);
                let post_state: VoteStateVersions = vote_account.borrow().state().unwrap();
                // State has been deinitialized since balance is zero
                assert!(post_state.is_uninitialized());
            }
        }

        // authorize authorized_withdrawer
        let authorized_withdrawer_pubkey = solana_sdk::pubkey::new_rand();
        let keyed_accounts = &[KeyedAccount::new(&vote_pubkey, true, &vote_account)];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let res = authorize(
            &keyed_accounts[0],
            &authorized_withdrawer_pubkey,
            VoteAuthorize::Withdrawer,
            &signers,
            &Clock::default(),
        );
        assert_eq!(res, Ok(()));

        // withdraw using authorized_withdrawer to authorized_withdrawer's account
        let withdrawer_account = RefCell::new(AccountSharedData::default());
        let keyed_accounts = &[
            KeyedAccount::new(&vote_pubkey, false, &vote_account),
            KeyedAccount::new(&authorized_withdrawer_pubkey, true, &withdrawer_account),
        ];
        let signers: HashSet<Pubkey> = get_signers(keyed_accounts);
        let vote_keyed_account = keyed_account_at_index(keyed_accounts, 0).unwrap();
        let withdrawer_keyed_account = keyed_account_at_index(keyed_accounts, 1).unwrap();
        let res = withdraw(
            vote_keyed_account,
            lamports,
            withdrawer_keyed_account,
            &signers,
            None,
        );
        assert_eq!(res, Ok(()));
        assert_eq!(vote_account.borrow().lamports(), 0);
        assert_eq!(withdrawer_account.borrow().lamports(), lamports);
        let post_state: VoteStateVersions = vote_account.borrow().state().unwrap();
        // State has been deinitialized since balance is zero
        assert!(post_state.is_uninitialized());
    }

    #[test]
    fn test_vote_state_epoch_credits() {
        let mut vote_state = VoteState::default();

        assert_eq!(vote_state.credits(), 0);
        assert_eq!(vote_state.epoch_credits().clone(), vec![]);

        let mut expected = vec![];
        let mut credits = 0;
        let epochs = (MAX_EPOCH_CREDITS_HISTORY + 2) as u64;
        for epoch in 0..epochs {
            for _j in 0..epoch {
                vote_state.increment_credits(epoch);
                credits += 1;
            }
            expected.push((epoch, credits, credits - epoch));
        }

        while expected.len() > MAX_EPOCH_CREDITS_HISTORY {
            expected.remove(0);
        }

        assert_eq!(vote_state.credits(), credits);
        assert_eq!(vote_state.epoch_credits().clone(), expected);
    }

    #[test]
    fn test_vote_state_epoch0_no_credits() {
        let mut vote_state = VoteState::default();

        assert_eq!(vote_state.epoch_credits().len(), 0);
        vote_state.increment_credits(1);
        assert_eq!(vote_state.epoch_credits().len(), 1);

        vote_state.increment_credits(2);
        assert_eq!(vote_state.epoch_credits().len(), 2);
    }

    #[test]
    fn test_vote_state_increment_credits() {
        let mut vote_state = VoteState::default();

        let credits = (MAX_EPOCH_CREDITS_HISTORY + 2) as u64;
        for i in 0..credits {
            vote_state.increment_credits(i as u64);
        }
        assert_eq!(vote_state.credits(), credits);
        assert!(vote_state.epoch_credits().len() <= MAX_EPOCH_CREDITS_HISTORY);
    }

    #[test]
    fn test_vote_process_timestamp() {
        let (slot, timestamp) = (15, 1_575_412_285);
        let mut vote_state = VoteState {
            last_timestamp: BlockTimestamp { slot, timestamp },
            ..VoteState::default()
        };

        assert_eq!(
            vote_state.process_timestamp(slot - 1, timestamp + 1),
            Err(VoteError::TimestampTooOld)
        );
        assert_eq!(
            vote_state.last_timestamp,
            BlockTimestamp { slot, timestamp }
        );
        assert_eq!(
            vote_state.process_timestamp(slot + 1, timestamp - 1),
            Err(VoteError::TimestampTooOld)
        );
        assert_eq!(
            vote_state.process_timestamp(slot, timestamp + 1),
            Err(VoteError::TimestampTooOld)
        );
        assert_eq!(vote_state.process_timestamp(slot, timestamp), Ok(()));
        assert_eq!(
            vote_state.last_timestamp,
            BlockTimestamp { slot, timestamp }
        );
        assert_eq!(vote_state.process_timestamp(slot + 1, timestamp), Ok(()));
        assert_eq!(
            vote_state.last_timestamp,
            BlockTimestamp {
                slot: slot + 1,
                timestamp
            }
        );
        assert_eq!(
            vote_state.process_timestamp(slot + 2, timestamp + 1),
            Ok(())
        );
        assert_eq!(
            vote_state.last_timestamp,
            BlockTimestamp {
                slot: slot + 2,
                timestamp: timestamp + 1
            }
        );

        // Test initial vote
        vote_state.last_timestamp = BlockTimestamp::default();
        assert_eq!(vote_state.process_timestamp(0, timestamp), Ok(()));
    }

    #[test]
    fn test_get_and_update_authorized_voter() {
        let original_voter = solana_sdk::pubkey::new_rand();
        let mut vote_state = VoteState::new(
            &VoteInit {
                node_pubkey: original_voter,
                authorized_voter: original_voter,
                authorized_withdrawer: original_voter,
                commission: 0,
            },
            &Clock::default(),
        );

        // If no new authorized voter was set, the same authorized voter
        // is locked into the next epoch
        assert_eq!(
            vote_state.get_and_update_authorized_voter(1).unwrap(),
            original_voter
        );

        // Try to get the authorized voter for epoch 5, implies
        // the authorized voter for epochs 1-4 were unchanged
        assert_eq!(
            vote_state.get_and_update_authorized_voter(5).unwrap(),
            original_voter
        );

        // Authorized voter for expired epoch 0..5 should have been
        // purged and no longer queryable
        assert_eq!(vote_state.authorized_voters.len(), 1);
        for i in 0..5 {
            assert!(vote_state
                .authorized_voters
                .get_authorized_voter(i)
                .is_none());
        }

        // Set an authorized voter change at slot 7
        let new_authorized_voter = solana_sdk::pubkey::new_rand();
        vote_state
            .set_new_authorized_voter(&new_authorized_voter, 5, 7, |_| Ok(()))
            .unwrap();

        // Try to get the authorized voter for epoch 6, unchanged
        assert_eq!(
            vote_state.get_and_update_authorized_voter(6).unwrap(),
            original_voter
        );

        // Try to get the authorized voter for epoch 7 and onwards, should
        // be the new authorized voter
        for i in 7..10 {
            assert_eq!(
                vote_state.get_and_update_authorized_voter(i).unwrap(),
                new_authorized_voter
            );
        }
        assert_eq!(vote_state.authorized_voters.len(), 1);
    }

    #[test]
    fn test_set_new_authorized_voter() {
        let original_voter = solana_sdk::pubkey::new_rand();
        let epoch_offset = 15;
        let mut vote_state = VoteState::new(
            &VoteInit {
                node_pubkey: original_voter,
                authorized_voter: original_voter,
                authorized_withdrawer: original_voter,
                commission: 0,
            },
            &Clock::default(),
        );

        assert!(vote_state.prior_voters.last().is_none());

        let new_voter = solana_sdk::pubkey::new_rand();
        // Set a new authorized voter
        vote_state
            .set_new_authorized_voter(&new_voter, 0, epoch_offset, |_| Ok(()))
            .unwrap();

        assert_eq!(vote_state.prior_voters.idx, 0);
        assert_eq!(
            vote_state.prior_voters.last(),
            Some(&(original_voter, 0, epoch_offset))
        );

        // Trying to set authorized voter for same epoch again should fail
        assert_eq!(
            vote_state.set_new_authorized_voter(&new_voter, 0, epoch_offset, |_| Ok(())),
            Err(VoteError::TooSoonToReauthorize.into())
        );

        // Setting the same authorized voter again should succeed
        vote_state
            .set_new_authorized_voter(&new_voter, 2, 2 + epoch_offset, |_| Ok(()))
            .unwrap();

        // Set a third and fourth authorized voter
        let new_voter2 = solana_sdk::pubkey::new_rand();
        vote_state
            .set_new_authorized_voter(&new_voter2, 3, 3 + epoch_offset, |_| Ok(()))
            .unwrap();
        assert_eq!(vote_state.prior_voters.idx, 1);
        assert_eq!(
            vote_state.prior_voters.last(),
            Some(&(new_voter, epoch_offset, 3 + epoch_offset))
        );

        let new_voter3 = solana_sdk::pubkey::new_rand();
        vote_state
            .set_new_authorized_voter(&new_voter3, 6, 6 + epoch_offset, |_| Ok(()))
            .unwrap();
        assert_eq!(vote_state.prior_voters.idx, 2);
        assert_eq!(
            vote_state.prior_voters.last(),
            Some(&(new_voter2, 3 + epoch_offset, 6 + epoch_offset))
        );

        // Check can set back to original voter
        vote_state
            .set_new_authorized_voter(&original_voter, 9, 9 + epoch_offset, |_| Ok(()))
            .unwrap();

        // Run with these voters for a while, check the ranges of authorized
        // voters is correct
        for i in 9..epoch_offset {
            assert_eq!(
                vote_state.get_and_update_authorized_voter(i).unwrap(),
                original_voter
            );
        }
        for i in epoch_offset..3 + epoch_offset {
            assert_eq!(
                vote_state.get_and_update_authorized_voter(i).unwrap(),
                new_voter
            );
        }
        for i in 3 + epoch_offset..6 + epoch_offset {
            assert_eq!(
                vote_state.get_and_update_authorized_voter(i).unwrap(),
                new_voter2
            );
        }
        for i in 6 + epoch_offset..9 + epoch_offset {
            assert_eq!(
                vote_state.get_and_update_authorized_voter(i).unwrap(),
                new_voter3
            );
        }
        for i in 9 + epoch_offset..=10 + epoch_offset {
            assert_eq!(
                vote_state.get_and_update_authorized_voter(i).unwrap(),
                original_voter
            );
        }
    }

    #[test]
    fn test_authorized_voter_is_locked_within_epoch() {
        let original_voter = solana_sdk::pubkey::new_rand();
        let mut vote_state = VoteState::new(
            &VoteInit {
                node_pubkey: original_voter,
                authorized_voter: original_voter,
                authorized_withdrawer: original_voter,
                commission: 0,
            },
            &Clock::default(),
        );

        // Test that it's not possible to set a new authorized
        // voter within the same epoch, even if none has been
        // explicitly set before
        let new_voter = solana_sdk::pubkey::new_rand();
        assert_eq!(
            vote_state.set_new_authorized_voter(&new_voter, 1, 1, |_| Ok(())),
            Err(VoteError::TooSoonToReauthorize.into())
        );

        assert_eq!(vote_state.get_authorized_voter(1), Some(original_voter));

        // Set a new authorized voter for a future epoch
        assert_eq!(
            vote_state.set_new_authorized_voter(&new_voter, 1, 2, |_| Ok(())),
            Ok(())
        );

        // Test that it's not possible to set a new authorized
        // voter within the same epoch, even if none has been
        // explicitly set before
        assert_eq!(
            vote_state.set_new_authorized_voter(&original_voter, 3, 3, |_| Ok(())),
            Err(VoteError::TooSoonToReauthorize.into())
        );

        assert_eq!(vote_state.get_authorized_voter(3), Some(new_voter));
    }

    #[test]
    fn test_vote_state_max_size() {
        let mut max_sized_data = vec![0; VoteState::size_of()];
        let vote_state = VoteState::get_max_sized_vote_state();
        let (start_leader_schedule_epoch, _) = vote_state.authorized_voters.last().unwrap();
        let start_current_epoch =
            start_leader_schedule_epoch - MAX_LEADER_SCHEDULE_EPOCH_OFFSET + 1;

        let mut vote_state = Some(vote_state);
        for i in start_current_epoch..start_current_epoch + 2 * MAX_LEADER_SCHEDULE_EPOCH_OFFSET {
            vote_state.as_mut().map(|vote_state| {
                vote_state.set_new_authorized_voter(
                    &solana_sdk::pubkey::new_rand(),
                    i,
                    i + MAX_LEADER_SCHEDULE_EPOCH_OFFSET,
                    |_| Ok(()),
                )
            });

            let versioned = VoteStateVersions::new_current(vote_state.take().unwrap());
            VoteState::serialize(&versioned, &mut max_sized_data).unwrap();
            vote_state = Some(versioned.convert_to_current());
        }
    }

    #[test]
    fn test_default_vote_state_is_uninitialized() {
        // The default `VoteState` is stored to de-initialize a zero-balance vote account,
        // so must remain such that `VoteStateVersions::is_uninitialized()` returns true
        // when called on a `VoteStateVersions` that stores it
        assert!(VoteStateVersions::new_current(VoteState::default()).is_uninitialized());
    }

    #[test]
    fn test_is_correct_size_and_initialized() {
        // Check all zeroes
        let mut vote_account_data = vec![0; VoteState::size_of()];
        assert!(!VoteState::is_correct_size_and_initialized(
            &vote_account_data
        ));

        // Check default VoteState
        let default_account_state = VoteStateVersions::new_current(VoteState::default());
        VoteState::serialize(&default_account_state, &mut vote_account_data).unwrap();
        assert!(!VoteState::is_correct_size_and_initialized(
            &vote_account_data
        ));

        // Check non-zero data shorter than offset index used
        let short_data = vec![1; DEFAULT_PRIOR_VOTERS_OFFSET];
        assert!(!VoteState::is_correct_size_and_initialized(&short_data));

        // Check non-zero large account
        let mut large_vote_data = vec![1; 2 * VoteState::size_of()];
        let default_account_state = VoteStateVersions::new_current(VoteState::default());
        VoteState::serialize(&default_account_state, &mut large_vote_data).unwrap();
        assert!(!VoteState::is_correct_size_and_initialized(
            &vote_account_data
        ));

        // Check populated VoteState
        let account_state = VoteStateVersions::new_current(VoteState::new(
            &VoteInit {
                node_pubkey: Pubkey::new_unique(),
                authorized_voter: Pubkey::new_unique(),
                authorized_withdrawer: Pubkey::new_unique(),
                commission: 0,
            },
            &Clock::default(),
        ));
        VoteState::serialize(&account_state, &mut vote_account_data).unwrap();
        assert!(VoteState::is_correct_size_and_initialized(
            &vote_account_data
        ));
    }

    #[test]
    fn test_process_new_vote_too_many_votes() {
        let mut vote_state1 = VoteState::default();
        let bad_votes: VecDeque<Lockout> = (0..=MAX_LOCKOUT_HISTORY)
            .map(|slot| Lockout {
                slot: slot as Slot,
                confirmation_count: (MAX_LOCKOUT_HISTORY - slot + 1) as u32,
            })
            .collect();

        assert_eq!(
            vote_state1.process_new_vote_state(bad_votes, None, None, vote_state1.current_epoch(),),
            Err(VoteError::TooManyVotes)
        );
    }

    #[test]
    fn test_process_new_vote_state_root_rollback() {
        let mut vote_state1 = VoteState::default();
        for i in 0..MAX_LOCKOUT_HISTORY + 2 {
            vote_state1.process_slot_vote_unchecked(i as Slot);
        }
        assert_eq!(vote_state1.root_slot.unwrap(), 1);

        // Update vote_state2 with a higher slot so that `process_new_vote_state`
        // doesn't panic.
        let mut vote_state2 = vote_state1.clone();
        vote_state2.process_slot_vote_unchecked(MAX_LOCKOUT_HISTORY as Slot + 3);

        // Trying to set a lesser root should error
        let lesser_root = Some(0);

        assert_eq!(
            vote_state1.process_new_vote_state(
                vote_state2.votes.clone(),
                lesser_root,
                None,
                vote_state2.current_epoch(),
            ),
            Err(VoteError::RootRollBack)
        );

        // Trying to set root to None should error
        let none_root = None;
        assert_eq!(
            vote_state1.process_new_vote_state(
                vote_state2.votes.clone(),
                none_root,
                None,
                vote_state2.current_epoch(),
            ),
            Err(VoteError::RootRollBack)
        );
    }

    #[test]
    fn test_process_new_vote_state_zero_confirmations() {
        let mut vote_state1 = VoteState::default();

        let bad_votes: VecDeque<Lockout> = vec![
            Lockout {
                slot: 0,
                confirmation_count: 0,
            },
            Lockout {
                slot: 1,
                confirmation_count: 1,
            },
        ]
        .into_iter()
        .collect();
        assert_eq!(
            vote_state1.process_new_vote_state(bad_votes, None, None, vote_state1.current_epoch(),),
            Err(VoteError::ZeroConfirmations)
        );

        let bad_votes: VecDeque<Lockout> = vec![
            Lockout {
                slot: 0,
                confirmation_count: 2,
            },
            Lockout {
                slot: 1,
                confirmation_count: 0,
            },
        ]
        .into_iter()
        .collect();
        assert_eq!(
            vote_state1.process_new_vote_state(bad_votes, None, None, vote_state1.current_epoch(),),
            Err(VoteError::ZeroConfirmations)
        );
    }

    #[test]
    fn test_process_new_vote_state_confirmations_too_large() {
        let mut vote_state1 = VoteState::default();

        let good_votes: VecDeque<Lockout> = vec![Lockout {
            slot: 0,
            confirmation_count: MAX_LOCKOUT_HISTORY as u32,
        }]
        .into_iter()
        .collect();

        vote_state1
            .process_new_vote_state(good_votes, None, None, vote_state1.current_epoch())
            .unwrap();

        let mut vote_state1 = VoteState::default();
        let bad_votes: VecDeque<Lockout> = vec![Lockout {
            slot: 0,
            confirmation_count: MAX_LOCKOUT_HISTORY as u32 + 1,
        }]
        .into_iter()
        .collect();
        assert_eq!(
            vote_state1.process_new_vote_state(bad_votes, None, None, vote_state1.current_epoch(),),
            Err(VoteError::ConfirmationTooLarge)
        );
    }

    #[test]
    fn test_process_new_vote_state_slot_smaller_than_root() {
        let mut vote_state1 = VoteState::default();
        let root_slot = 5;

        let bad_votes: VecDeque<Lockout> = vec![
            Lockout {
                slot: root_slot,
                confirmation_count: 2,
            },
            Lockout {
                slot: root_slot + 1,
                confirmation_count: 1,
            },
        ]
        .into_iter()
        .collect();
        assert_eq!(
            vote_state1.process_new_vote_state(
                bad_votes,
                Some(root_slot),
                None,
                vote_state1.current_epoch(),
            ),
            Err(VoteError::SlotSmallerThanRoot)
        );

        let bad_votes: VecDeque<Lockout> = vec![
            Lockout {
                slot: root_slot - 1,
                confirmation_count: 2,
            },
            Lockout {
                slot: root_slot + 1,
                confirmation_count: 1,
            },
        ]
        .into_iter()
        .collect();
        assert_eq!(
            vote_state1.process_new_vote_state(
                bad_votes,
                Some(root_slot),
                None,
                vote_state1.current_epoch(),
            ),
            Err(VoteError::SlotSmallerThanRoot)
        );
    }

    #[test]
    fn test_process_new_vote_state_slots_not_ordered() {
        let mut vote_state1 = VoteState::default();

        let bad_votes: VecDeque<Lockout> = vec![
            Lockout {
                slot: 1,
                confirmation_count: 2,
            },
            Lockout {
                slot: 0,
                confirmation_count: 1,
            },
        ]
        .into_iter()
        .collect();
        assert_eq!(
            vote_state1.process_new_vote_state(bad_votes, None, None, vote_state1.current_epoch(),),
            Err(VoteError::SlotsNotOrdered)
        );

        let bad_votes: VecDeque<Lockout> = vec![
            Lockout {
                slot: 1,
                confirmation_count: 2,
            },
            Lockout {
                slot: 1,
                confirmation_count: 1,
            },
        ]
        .into_iter()
        .collect();
        assert_eq!(
            vote_state1.process_new_vote_state(bad_votes, None, None, vote_state1.current_epoch(),),
            Err(VoteError::SlotsNotOrdered)
        );
    }

    #[test]
    fn test_process_new_vote_state_confirmations_not_ordered() {
        let mut vote_state1 = VoteState::default();

        let bad_votes: VecDeque<Lockout> = vec![
            Lockout {
                slot: 0,
                confirmation_count: 1,
            },
            Lockout {
                slot: 1,
                confirmation_count: 2,
            },
        ]
        .into_iter()
        .collect();
        assert_eq!(
            vote_state1.process_new_vote_state(bad_votes, None, None, vote_state1.current_epoch(),),
            Err(VoteError::ConfirmationsNotOrdered)
        );

        let bad_votes: VecDeque<Lockout> = vec![
            Lockout {
                slot: 0,
                confirmation_count: 1,
            },
            Lockout {
                slot: 1,
                confirmation_count: 1,
            },
        ]
        .into_iter()
        .collect();
        assert_eq!(
            vote_state1.process_new_vote_state(bad_votes, None, None, vote_state1.current_epoch(),),
            Err(VoteError::ConfirmationsNotOrdered)
        );
    }

    #[test]
    fn test_process_new_vote_state_new_vote_state_lockout_mismatch() {
        let mut vote_state1 = VoteState::default();

        let bad_votes: VecDeque<Lockout> = vec![
            Lockout {
                slot: 0,
                confirmation_count: 2,
            },
            Lockout {
                slot: 7,
                confirmation_count: 1,
            },
        ]
        .into_iter()
        .collect();

        // Slot 7 should have expired slot 0
        assert_eq!(
            vote_state1.process_new_vote_state(bad_votes, None, None, vote_state1.current_epoch(),),
            Err(VoteError::NewVoteStateLockoutMismatch)
        );
    }

    #[test]
    fn test_process_new_vote_state_confirmation_rollback() {
        let mut vote_state1 = VoteState::default();
        let votes: VecDeque<Lockout> = vec![
            Lockout {
                slot: 0,
                confirmation_count: 4,
            },
            Lockout {
                slot: 1,
                confirmation_count: 3,
            },
        ]
        .into_iter()
        .collect();
        vote_state1
            .process_new_vote_state(votes, None, None, vote_state1.current_epoch())
            .unwrap();

        let votes: VecDeque<Lockout> = vec![
            Lockout {
                slot: 0,
                confirmation_count: 4,
            },
            Lockout {
                slot: 1,
                // Confirmation count lowered illegally
                confirmation_count: 2,
            },
            Lockout {
                slot: 2,
                confirmation_count: 1,
            },
        ]
        .into_iter()
        .collect();
        // Should error because newer vote state should not have lower confirmation the same slot
        // 1
        assert_eq!(
            vote_state1.process_new_vote_state(votes, None, None, vote_state1.current_epoch(),),
            Err(VoteError::ConfirmationRollBack)
        );
    }

    #[test]
    fn test_process_new_vote_state_root_progress() {
        let mut vote_state1 = VoteState::default();
        for i in 0..MAX_LOCKOUT_HISTORY {
            vote_state1.process_slot_vote_unchecked(i as u64);
        }

        assert!(vote_state1.root_slot.is_none());
        let mut vote_state2 = vote_state1.clone();

        // 1) Try to update `vote_state1` with no root,
        // to `vote_state2`, which has a new root, should succeed.
        //
        // 2) Then try to update`vote_state1` with an existing root,
        // to `vote_state2`, which has a newer root, which
        // should succeed.
        for new_vote in MAX_LOCKOUT_HISTORY + 1..=MAX_LOCKOUT_HISTORY + 2 {
            vote_state2.process_slot_vote_unchecked(new_vote as Slot);
            assert_ne!(vote_state1.root_slot, vote_state2.root_slot);

            vote_state1
                .process_new_vote_state(
                    vote_state2.votes.clone(),
                    vote_state2.root_slot,
                    None,
                    vote_state2.current_epoch(),
                )
                .unwrap();

            assert_eq!(vote_state1, vote_state2);
        }
    }

    #[test]
    fn test_process_new_vote_state_same_slot_but_not_common_ancestor() {
        // It might be possible that during the switch from old vote instructions
        // to new vote instructions, new_state contains votes for slots LESS
        // than the current state, for instance:
        //
        // Current on-chain state: 1, 5
        // New state: 1, 2 (lockout: 4), 3, 5, 7
        //
        // Imagine the validator made two of these votes:
        // 1) The first vote {1, 2, 3} didn't land in the old state, but didn't
        // land on chain
        // 2) A second vote {1, 2, 5} was then submitted, which landed
        //
        //
        // 2 is not popped off in the local tower because 3 doubled the lockout.
        // However, 3 did not land in the on-chain state, so the vote {1, 2, 6}
        // will immediately pop off 2.

        // Construct on-chain vote state
        let mut vote_state1 = VoteState::default();
        vote_state1.process_slot_votes_unchecked(&[1, 2, 5]);
        assert_eq!(
            vote_state1
                .votes
                .iter()
                .map(|vote| vote.slot)
                .collect::<Vec<Slot>>(),
            vec![1, 5]
        );

        // Construct local tower state
        let mut vote_state2 = VoteState::default();
        vote_state2.process_slot_votes_unchecked(&[1, 2, 3, 5, 7]);
        assert_eq!(
            vote_state2
                .votes
                .iter()
                .map(|vote| vote.slot)
                .collect::<Vec<Slot>>(),
            vec![1, 2, 3, 5, 7]
        );

        // See that on-chain vote state can update properly
        vote_state1
            .process_new_vote_state(
                vote_state2.votes.clone(),
                vote_state2.root_slot,
                None,
                vote_state2.current_epoch(),
            )
            .unwrap();

        assert_eq!(vote_state1, vote_state2);
    }

    #[test]
    fn test_process_new_vote_state_lockout_violation() {
        // Construct on-chain vote state
        let mut vote_state1 = VoteState::default();
        vote_state1.process_slot_votes_unchecked(&[1, 2, 4, 5]);
        assert_eq!(
            vote_state1
                .votes
                .iter()
                .map(|vote| vote.slot)
                .collect::<Vec<Slot>>(),
            vec![1, 2, 4, 5]
        );

        // Construct conflicting tower state. Vote 4 is missing,
        // but 5 should not have popped off vote 4.
        let mut vote_state2 = VoteState::default();
        vote_state2.process_slot_votes_unchecked(&[1, 2, 3, 5, 7]);
        assert_eq!(
            vote_state2
                .votes
                .iter()
                .map(|vote| vote.slot)
                .collect::<Vec<Slot>>(),
            vec![1, 2, 3, 5, 7]
        );

        // See that on-chain vote state can update properly
        assert_eq!(
            vote_state1.process_new_vote_state(
                vote_state2.votes.clone(),
                vote_state2.root_slot,
                None,
                vote_state2.current_epoch(),
            ),
            Err(VoteError::LockoutConflict)
        );
    }

    #[test]
    fn test_process_new_vote_state_lockout_violation2() {
        // Construct on-chain vote state
        let mut vote_state1 = VoteState::default();
        vote_state1.process_slot_votes_unchecked(&[1, 2, 5, 6, 7]);
        assert_eq!(
            vote_state1
                .votes
                .iter()
                .map(|vote| vote.slot)
                .collect::<Vec<Slot>>(),
            vec![1, 5, 6, 7]
        );

        // Construct a new vote state. Violates on-chain state because 8
        // should not have popped off 7
        let mut vote_state2 = VoteState::default();
        vote_state2.process_slot_votes_unchecked(&[1, 2, 3, 5, 6, 8]);
        assert_eq!(
            vote_state2
                .votes
                .iter()
                .map(|vote| vote.slot)
                .collect::<Vec<Slot>>(),
            vec![1, 2, 3, 5, 6, 8]
        );

        // Both vote states contain `5`, but `5` is not part of the common prefix
        // of both vote states. However, the violation should still be detected.
        assert_eq!(
            vote_state1.process_new_vote_state(
                vote_state2.votes.clone(),
                vote_state2.root_slot,
                None,
                vote_state2.current_epoch(),
            ),
            Err(VoteError::LockoutConflict)
        );
    }

    #[test]
    fn test_process_new_vote_state_expired_ancestor_not_removed() {
        // Construct on-chain vote state
        let mut vote_state1 = VoteState::default();
        vote_state1.process_slot_votes_unchecked(&[1, 2, 3, 9]);
        assert_eq!(
            vote_state1
                .votes
                .iter()
                .map(|vote| vote.slot)
                .collect::<Vec<Slot>>(),
            vec![1, 9]
        );

        // Example: {1: lockout 8, 9: lockout 2}, vote on 10 will not pop off 1
        // because 9 is not popped off yet
        let mut vote_state2 = vote_state1.clone();
        vote_state2.process_slot_vote_unchecked(10);

        // Slot 1 has been expired by 10, but is kept alive by its descendant
        // 9 which has not been expired yet.
        assert_eq!(vote_state2.votes[0].slot, 1);
        assert_eq!(vote_state2.votes[0].last_locked_out_slot(), 9);
        assert_eq!(
            vote_state2
                .votes
                .iter()
                .map(|vote| vote.slot)
                .collect::<Vec<Slot>>(),
            vec![1, 9, 10]
        );

        // Should be able to update vote_state1
        vote_state1
            .process_new_vote_state(
                vote_state2.votes.clone(),
                vote_state2.root_slot,
                None,
                vote_state2.current_epoch(),
            )
            .unwrap();
        assert_eq!(vote_state1, vote_state2,);
    }

    #[test]
    fn test_process_new_vote_current_state_contains_bigger_slots() {
        let mut vote_state1 = VoteState::default();
        vote_state1.process_slot_votes_unchecked(&[6, 7, 8]);
        assert_eq!(
            vote_state1
                .votes
                .iter()
                .map(|vote| vote.slot)
                .collect::<Vec<Slot>>(),
            vec![6, 7, 8]
        );

        // Try to process something with lockout violations
        let bad_votes: VecDeque<Lockout> = vec![
            Lockout {
                slot: 2,
                confirmation_count: 5,
            },
            Lockout {
                // Slot 14 could not have popped off slot 6 yet
                slot: 14,
                confirmation_count: 1,
            },
        ]
        .into_iter()
        .collect();
        let root = Some(1);

        assert_eq!(
            vote_state1.process_new_vote_state(bad_votes, root, None, vote_state1.current_epoch(),),
            Err(VoteError::LockoutConflict)
        );

        let good_votes: VecDeque<Lockout> = vec![
            Lockout {
                slot: 2,
                confirmation_count: 5,
            },
            Lockout {
                slot: 15,
                confirmation_count: 1,
            },
        ]
        .into_iter()
        .collect();

        vote_state1
            .process_new_vote_state(good_votes.clone(), root, None, vote_state1.current_epoch())
            .unwrap();
        assert_eq!(vote_state1.votes, good_votes);
    }
}