zebra/zebra-consensus/src/checkpoint/tests.rs

//! Tests for checkpoint-based block verification

use super::*;

use super::types::Progress::*;
use super::types::Target::*;

use color_eyre::eyre::{eyre, Report};
use futures::{future::TryFutureExt, stream::FuturesUnordered};
use std::{cmp::min, mem::drop, time::Duration};
use tokio::{stream::StreamExt, time::timeout};
use tower::{Service, ServiceExt};
use tracing_futures::Instrument;

use zebra_chain::serialization::ZcashDeserialize;

/// The timeout we apply to each verify future during testing.
///
/// The checkpoint verifier uses `tokio::sync::oneshot` channels as futures.
/// If the verifier doesn't send a message on the channel, any tests that
/// await the channel future will hang.
///
/// This value is set to a large value, to avoid spurious failures due to
/// high system load.
const VERIFY_TIMEOUT_SECONDS: u64 = 10;

#[tokio::test]
async fn single_item_checkpoint_list_test() -> Result<(), Report> {
    single_item_checkpoint_list().await
}

#[spandoc::spandoc]
async fn single_item_checkpoint_list() -> Result<(), Report> {
    zebra_test::init();

    let block0 =
        Arc::<Block>::zcash_deserialize(&zebra_test::vectors::BLOCK_MAINNET_GENESIS_BYTES[..])?;
    let hash0 = block0.hash();

    // Make a checkpoint list containing only the genesis block
    let genesis_checkpoint_list: BTreeMap<BlockHeight, block::Hash> =
        [(block0.coinbase_height().unwrap(), hash0)]
            .iter()
            .cloned()
            .collect();

    let mut checkpoint_verifier =
        CheckpointVerifier::from_list(genesis_checkpoint_list, None).map_err(|e| eyre!(e))?;

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        BeforeGenesis
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        WaitingForBlocks
    );
    assert_eq!(
        checkpoint_verifier.checkpoint_list.max_height(),
        BlockHeight(0)
    );

    /// SPANDOC: Make sure the verifier service is ready
    let ready_verifier_service = checkpoint_verifier
        .ready_and()
        .map_err(|e| eyre!(e))
        .await?;
    /// SPANDOC: Set up the future for block 0
    let verify_future = timeout(
        Duration::from_secs(VERIFY_TIMEOUT_SECONDS),
        ready_verifier_service.call(block0.clone()),
    );
    /// SPANDOC: Wait for the response for block 0
    // TODO(teor || jlusby): check error kind
    let verify_response = verify_future
        .map_err(|e| eyre!(e))
        .await
        .expect("timeout should not happen")
        .expect("block should verify");

    assert_eq!(verify_response, hash0);

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        FinalCheckpoint
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        FinishedVerifying
    );
    assert_eq!(
        checkpoint_verifier.checkpoint_list.max_height(),
        BlockHeight(0)
    );

    Ok(())
}

#[tokio::test]
async fn multi_item_checkpoint_list_test() -> Result<(), Report> {
    multi_item_checkpoint_list().await
}

#[spandoc::spandoc]
async fn multi_item_checkpoint_list() -> Result<(), Report> {
    zebra_test::init();

    // Parse all the blocks
    let mut checkpoint_data = Vec::new();
    for b in &[
        // This list is used as a checkpoint list, and as a list of blocks to
        // verify. So it must be continuous.
        &zebra_test::vectors::BLOCK_MAINNET_GENESIS_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_1_BYTES[..],
    ] {
        let block = Arc::<Block>::zcash_deserialize(*b)?;
        let hash = block.hash();
        checkpoint_data.push((block.clone(), block.coinbase_height().unwrap(), hash));
    }

    // Make a checkpoint list containing all the blocks
    let checkpoint_list: BTreeMap<BlockHeight, block::Hash> = checkpoint_data
        .iter()
        .map(|(_block, height, hash)| (*height, *hash))
        .collect();

    let mut checkpoint_verifier =
        CheckpointVerifier::from_list(checkpoint_list, None).map_err(|e| eyre!(e))?;

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        BeforeGenesis
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        WaitingForBlocks
    );
    assert_eq!(
        checkpoint_verifier.checkpoint_list.max_height(),
        BlockHeight(1)
    );

    // Now verify each block
    for (block, height, hash) in checkpoint_data {
        /// SPANDOC: Make sure the verifier service is ready
        let ready_verifier_service = checkpoint_verifier
            .ready_and()
            .map_err(|e| eyre!(e))
            .await?;

        /// SPANDOC: Set up the future for block {?height}
        let verify_future = timeout(
            Duration::from_secs(VERIFY_TIMEOUT_SECONDS),
            ready_verifier_service.call(block.clone()),
        );
        /// SPANDOC: Wait for the response for block {?height}
        // TODO(teor || jlusby): check error kind
        let verify_response = verify_future
            .map_err(|e| eyre!(e))
            .await
            .expect("timeout should not happen")
            .expect("future should succeed");

        assert_eq!(verify_response, hash);

        if height < checkpoint_verifier.checkpoint_list.max_height() {
            assert_eq!(
                checkpoint_verifier.previous_checkpoint_height(),
                PreviousCheckpoint(height)
            );
            assert_eq!(
                checkpoint_verifier.target_checkpoint_height(),
                WaitingForBlocks
            );
        } else {
            assert_eq!(
                checkpoint_verifier.previous_checkpoint_height(),
                FinalCheckpoint
            );
            assert_eq!(
                checkpoint_verifier.target_checkpoint_height(),
                FinishedVerifying
            );
        }
        assert_eq!(
            checkpoint_verifier.checkpoint_list.max_height(),
            BlockHeight(1)
        );
    }

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        FinalCheckpoint
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        FinishedVerifying
    );
    assert_eq!(
        checkpoint_verifier.checkpoint_list.max_height(),
        BlockHeight(1)
    );

    Ok(())
}

#[tokio::test]
async fn continuous_blockchain_test() -> Result<(), Report> {
    continuous_blockchain(None).await?;
    for height in 0..=10 {
        continuous_blockchain(Some(BlockHeight(height))).await?;
    }
    Ok(())
}

/// Test a continuous blockchain, restarting verification at `restart_height`.
#[spandoc::spandoc]
async fn continuous_blockchain(restart_height: Option<BlockHeight>) -> Result<(), Report> {
    zebra_test::init();

    // A continuous blockchain
    let mut blockchain = Vec::new();
    for b in &[
        &zebra_test::vectors::BLOCK_MAINNET_GENESIS_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_1_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_2_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_3_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_4_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_5_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_6_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_7_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_8_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_9_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_10_BYTES[..],
    ] {
        let block = Arc::<Block>::zcash_deserialize(*b)?;
        let hash = block.hash();
        blockchain.push((block.clone(), block.coinbase_height().unwrap(), hash));
    }

    // Parse only some blocks as checkpoints
    let mut checkpoints = Vec::new();
    for b in &[
        &zebra_test::vectors::BLOCK_MAINNET_GENESIS_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_5_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_9_BYTES[..],
    ] {
        let block = Arc::<Block>::zcash_deserialize(*b)?;
        let hash = block.hash();
        checkpoints.push((block.clone(), block.coinbase_height().unwrap(), hash));
    }

    // The checkpoint list will contain only block 0, 5 and 9
    let checkpoint_list: BTreeMap<BlockHeight, block::Hash> = checkpoints
        .iter()
        .map(|(_block, height, hash)| (*height, *hash))
        .collect();

    /// SPANDOC: Verify blocks, restarting at {?restart_height}
    {
        let initial_tip = restart_height
            .map(|BlockHeight(height)| &blockchain[height as usize].0)
            .cloned();
        let mut checkpoint_verifier =
            CheckpointVerifier::from_list(checkpoint_list, initial_tip).map_err(|e| eyre!(e))?;

        // Setup checks
        if restart_height
            .map(|h| h >= checkpoint_verifier.checkpoint_list.max_height())
            .unwrap_or(false)
        {
            assert_eq!(
                checkpoint_verifier.previous_checkpoint_height(),
                FinalCheckpoint
            );
            assert_eq!(
                checkpoint_verifier.target_checkpoint_height(),
                FinishedVerifying
            );
        } else {
            assert_eq!(
                checkpoint_verifier.previous_checkpoint_height(),
                restart_height.map(InitialTip).unwrap_or(BeforeGenesis)
            );
            assert_eq!(
                checkpoint_verifier.target_checkpoint_height(),
                WaitingForBlocks
            );
        }
        assert_eq!(
            checkpoint_verifier.checkpoint_list.max_height(),
            BlockHeight(9)
        );

        let mut handles = FuturesUnordered::new();

        // Now verify each block
        for (block, height, _hash) in blockchain {
            if let Some(restart_height) = restart_height {
                if height <= restart_height {
                    continue;
                }
            }
            if height > checkpoint_verifier.checkpoint_list.max_height() {
                break;
            }

            /// SPANDOC: Make sure the verifier service is ready for block {?height}
            let ready_verifier_service = checkpoint_verifier
                .ready_and()
                .map_err(|e| eyre!(e))
                .await?;

            /// SPANDOC: Set up the future for block {?height}
            let verify_future = timeout(
                Duration::from_secs(VERIFY_TIMEOUT_SECONDS),
                ready_verifier_service.call(block.clone()),
            );

            /// SPANDOC: spawn verification future in the background for block {?height}
            let handle = tokio::spawn(verify_future.in_current_span());
            handles.push(handle);

            // Execution checks
            if height < checkpoint_verifier.checkpoint_list.max_height() {
                assert_eq!(
                    checkpoint_verifier.target_checkpoint_height(),
                    WaitingForBlocks
                );
            } else {
                assert_eq!(
                    checkpoint_verifier.previous_checkpoint_height(),
                    FinalCheckpoint
                );
                assert_eq!(
                    checkpoint_verifier.target_checkpoint_height(),
                    FinishedVerifying
                );
            }
        }

        while let Some(result) = handles.next().await {
            result??.map_err(|e| eyre!(e))?;
        }

        // Final checks
        assert_eq!(
            checkpoint_verifier.previous_checkpoint_height(),
            FinalCheckpoint
        );
        assert_eq!(
            checkpoint_verifier.target_checkpoint_height(),
            FinishedVerifying
        );
        assert_eq!(
            checkpoint_verifier.checkpoint_list.max_height(),
            BlockHeight(9)
        );
    }

    Ok(())
}

#[tokio::test]
async fn block_higher_than_max_checkpoint_fail_test() -> Result<(), Report> {
    block_higher_than_max_checkpoint_fail().await
}

#[spandoc::spandoc]
async fn block_higher_than_max_checkpoint_fail() -> Result<(), Report> {
    zebra_test::init();

    let block0 =
        Arc::<Block>::zcash_deserialize(&zebra_test::vectors::BLOCK_MAINNET_GENESIS_BYTES[..])?;
    let block415000 =
        Arc::<Block>::zcash_deserialize(&zebra_test::vectors::BLOCK_MAINNET_415000_BYTES[..])?;

    // Make a checkpoint list containing only the genesis block
    let genesis_checkpoint_list: BTreeMap<BlockHeight, block::Hash> =
        [(block0.coinbase_height().unwrap(), block0.as_ref().into())]
            .iter()
            .cloned()
            .collect();

    let mut checkpoint_verifier =
        CheckpointVerifier::from_list(genesis_checkpoint_list, None).map_err(|e| eyre!(e))?;

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        BeforeGenesis
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        WaitingForBlocks
    );
    assert_eq!(
        checkpoint_verifier.checkpoint_list.max_height(),
        BlockHeight(0)
    );

    /// SPANDOC: Make sure the verifier service is ready
    let ready_verifier_service = checkpoint_verifier
        .ready_and()
        .map_err(|e| eyre!(e))
        .await?;
    /// SPANDOC: Set up the future for block 415000
    let verify_future = timeout(
        Duration::from_secs(VERIFY_TIMEOUT_SECONDS),
        ready_verifier_service.call(block415000.clone()),
    );
    /// SPANDOC: Wait for the response for block 415000, and expect failure
    // TODO(teor || jlusby): check error kind
    let _ = verify_future
        .map_err(|e| eyre!(e))
        .await
        .expect("timeout should not happen")
        .expect_err("bad block hash should fail");

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        BeforeGenesis
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        WaitingForBlocks
    );
    assert_eq!(
        checkpoint_verifier.checkpoint_list.max_height(),
        BlockHeight(0)
    );

    Ok(())
}

#[tokio::test]
async fn wrong_checkpoint_hash_fail_test() -> Result<(), Report> {
    wrong_checkpoint_hash_fail().await
}

#[spandoc::spandoc]
async fn wrong_checkpoint_hash_fail() -> Result<(), Report> {
    zebra_test::init();

    let good_block0 =
        Arc::<Block>::zcash_deserialize(&zebra_test::vectors::BLOCK_MAINNET_GENESIS_BYTES[..])?;
    let good_block0_hash = good_block0.hash();
    // Change the header hash
    let mut bad_block0 = good_block0.clone();
    let mut bad_block0 = Arc::make_mut(&mut bad_block0);
    bad_block0.header.version = 0;
    let bad_block0: Arc<Block> = bad_block0.clone().into();

    // Make a checkpoint list containing the genesis block checkpoint
    let genesis_checkpoint_list: BTreeMap<BlockHeight, block::Hash> =
        [(good_block0.coinbase_height().unwrap(), good_block0_hash)]
            .iter()
            .cloned()
            .collect();

    let mut checkpoint_verifier =
        CheckpointVerifier::from_list(genesis_checkpoint_list, None).map_err(|e| eyre!(e))?;

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        BeforeGenesis
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        WaitingForBlocks
    );
    assert_eq!(
        checkpoint_verifier.checkpoint_list.max_height(),
        BlockHeight(0)
    );

    /// SPANDOC: Make sure the verifier service is ready (1/3)
    let ready_verifier_service = checkpoint_verifier
        .ready_and()
        .map_err(|e| eyre!(e))
        .await?;
    /// SPANDOC: Set up the future for bad block 0 (1/3)
    // TODO(teor || jlusby): check error kind
    let bad_verify_future_1 = timeout(
        Duration::from_secs(VERIFY_TIMEOUT_SECONDS),
        ready_verifier_service.call(bad_block0.clone()),
    );
    // We can't await the future yet, because bad blocks aren't cleared
    // until the chain is verified

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        BeforeGenesis
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        WaitingForBlocks
    );
    assert_eq!(
        checkpoint_verifier.checkpoint_list.max_height(),
        BlockHeight(0)
    );

    /// SPANDOC: Make sure the verifier service is ready (2/3)
    let ready_verifier_service = checkpoint_verifier
        .ready_and()
        .map_err(|e| eyre!(e))
        .await?;
    /// SPANDOC: Set up the future for bad block 0 again (2/3)
    // TODO(teor || jlusby): check error kind
    let bad_verify_future_2 = timeout(
        Duration::from_secs(VERIFY_TIMEOUT_SECONDS),
        ready_verifier_service.call(bad_block0.clone()),
    );
    // We can't await the future yet, because bad blocks aren't cleared
    // until the chain is verified

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        BeforeGenesis
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        WaitingForBlocks
    );
    assert_eq!(
        checkpoint_verifier.checkpoint_list.max_height(),
        BlockHeight(0)
    );

    /// SPANDOC: Make sure the verifier service is ready (3/3)
    let ready_verifier_service = checkpoint_verifier
        .ready_and()
        .map_err(|e| eyre!(e))
        .await?;
    /// SPANDOC: Set up the future for good block 0 (3/3)
    let good_verify_future = timeout(
        Duration::from_secs(VERIFY_TIMEOUT_SECONDS),
        ready_verifier_service.call(good_block0.clone()),
    );
    /// SPANDOC: Wait for the response for good block 0, and expect success (3/3)
    // TODO(teor || jlusby): check error kind
    let verify_response = good_verify_future
        .map_err(|e| eyre!(e))
        .await
        .expect("timeout should not happen")
        .expect("future should succeed");

    assert_eq!(verify_response, good_block0_hash);

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        FinalCheckpoint
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        FinishedVerifying
    );
    assert_eq!(
        checkpoint_verifier.checkpoint_list.max_height(),
        BlockHeight(0)
    );

    // Now, await the bad futures, which should have completed

    /// SPANDOC: Wait for the response for block 0, and expect failure (1/3)
    // TODO(teor || jlusby): check error kind
    let _ = bad_verify_future_1
        .map_err(|e| eyre!(e))
        .await
        .expect("timeout should not happen")
        .expect_err("bad block hash should fail");

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        FinalCheckpoint
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        FinishedVerifying
    );
    assert_eq!(
        checkpoint_verifier.checkpoint_list.max_height(),
        BlockHeight(0)
    );

    /// SPANDOC: Wait for the response for block 0, and expect failure again (2/3)
    // TODO(teor || jlusby): check error kind
    let _ = bad_verify_future_2
        .map_err(|e| eyre!(e))
        .await
        .expect("timeout should not happen")
        .expect_err("bad block hash should fail");

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        FinalCheckpoint
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        FinishedVerifying
    );
    assert_eq!(
        checkpoint_verifier.checkpoint_list.max_height(),
        BlockHeight(0)
    );

    Ok(())
}

#[tokio::test]
async fn checkpoint_drop_cancel_test() -> Result<(), Report> {
    checkpoint_drop_cancel().await
}

#[spandoc::spandoc]
async fn checkpoint_drop_cancel() -> Result<(), Report> {
    zebra_test::init();

    // Parse all the blocks
    let mut checkpoint_data = Vec::new();
    for b in &[
        // Continous blocks are verified
        &zebra_test::vectors::BLOCK_MAINNET_GENESIS_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_1_BYTES[..],
        // Other blocks can't verify, so they are rejected on drop
        &zebra_test::vectors::BLOCK_MAINNET_415000_BYTES[..],
        &zebra_test::vectors::BLOCK_MAINNET_434873_BYTES[..],
    ] {
        let block = Arc::<Block>::zcash_deserialize(*b)?;
        let hash = block.hash();
        checkpoint_data.push((block.clone(), block.coinbase_height().unwrap(), hash));
    }

    // Make a checkpoint list containing all the blocks
    let checkpoint_list: BTreeMap<BlockHeight, block::Hash> = checkpoint_data
        .iter()
        .map(|(_block, height, hash)| (*height, *hash))
        .collect();

    let mut checkpoint_verifier =
        CheckpointVerifier::from_list(checkpoint_list, None).map_err(|e| eyre!(e))?;

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        BeforeGenesis
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        WaitingForBlocks
    );
    assert_eq!(
        checkpoint_verifier.checkpoint_list.max_height(),
        BlockHeight(434873)
    );

    let mut futures = Vec::new();
    // Now collect verify futures for each block
    for (block, height, hash) in checkpoint_data {
        /// SPANDOC: Make sure the verifier service is ready
        let ready_verifier_service = checkpoint_verifier
            .ready_and()
            .map_err(|e| eyre!(e))
            .await?;

        /// SPANDOC: Set up the future for block {?height}
        let verify_future = timeout(
            Duration::from_secs(VERIFY_TIMEOUT_SECONDS),
            ready_verifier_service.call(block.clone()),
        );

        futures.push((verify_future, height, hash));

        // Only continuous checkpoints verify
        assert_eq!(
            checkpoint_verifier.previous_checkpoint_height(),
            PreviousCheckpoint(BlockHeight(min(height.0, 1)))
        );
        assert_eq!(
            checkpoint_verifier.target_checkpoint_height(),
            WaitingForBlocks
        );
        assert_eq!(
            checkpoint_verifier.checkpoint_list.max_height(),
            BlockHeight(434873)
        );
    }

    // Now drop the verifier, to cancel the futures
    drop(checkpoint_verifier);

    for (verify_future, height, hash) in futures {
        /// SPANDOC: Check the response for block {?height}
        let verify_response = verify_future
            .map_err(|e| eyre!(e))
            .await
            .expect("timeout should not happen");

        if height <= BlockHeight(1) {
            let verify_hash =
                verify_response.expect("Continuous checkpoints should have succeeded before drop");
            assert_eq!(verify_hash, hash);
        } else {
            // TODO(teor || jlusby): check error kind
            verify_response.expect_err("Pending futures should fail on drop");
        }
    }

    Ok(())
}

#[tokio::test]
async fn hard_coded_mainnet_test() -> Result<(), Report> {
    hard_coded_mainnet().await
}

#[spandoc::spandoc]
async fn hard_coded_mainnet() -> Result<(), Report> {
    zebra_test::init();

    let block0 =
        Arc::<Block>::zcash_deserialize(&zebra_test::vectors::BLOCK_MAINNET_GENESIS_BYTES[..])?;
    let hash0 = block0.hash();

    // Use the hard-coded checkpoint list
    let mut checkpoint_verifier = CheckpointVerifier::new(Network::Mainnet, None);

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        BeforeGenesis
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        WaitingForBlocks
    );
    assert!(checkpoint_verifier.checkpoint_list.max_height() > BlockHeight(0));

    /// SPANDOC: Make sure the verifier service is ready
    let ready_verifier_service = checkpoint_verifier
        .ready_and()
        .map_err(|e| eyre!(e))
        .await?;
    /// SPANDOC: Set up the future for block 0
    let verify_future = timeout(
        Duration::from_secs(VERIFY_TIMEOUT_SECONDS),
        ready_verifier_service.call(block0.clone()),
    );
    /// SPANDOC: Wait for the response for block 0
    // TODO(teor || jlusby): check error kind
    let verify_response = verify_future
        .map_err(|e| eyre!(e))
        .await
        .expect("timeout should not happen")
        .expect("block should verify");

    assert_eq!(verify_response, hash0);

    assert_eq!(
        checkpoint_verifier.previous_checkpoint_height(),
        PreviousCheckpoint(BlockHeight(0))
    );
    assert_eq!(
        checkpoint_verifier.target_checkpoint_height(),
        WaitingForBlocks
    );
    // The lists will get bigger over time, so we just pick a recent height
    assert!(checkpoint_verifier.checkpoint_list.max_height() > BlockHeight(900_000));

    Ok(())
}