zebra-consensus 5.0.0

//! Tests for Zcash transaction consensus checks.

#![allow(clippy::unwrap_in_result)]

//
// TODO: split fixed test vectors into a `vectors` module?

use std::{
    collections::{HashMap, HashSet},
    sync::Arc,
};

use chrono::{DateTime, TimeZone, Utc};
use color_eyre::eyre::Report;
use futures::{FutureExt, TryFutureExt};
use halo2::pasta::{group::ff::PrimeField, pallas};
use tokio::time::timeout;
use tower::{buffer::Buffer, service_fn, ServiceExt};

use zebra_chain::{
    amount::{Amount, NonNegative},
    block::{self, Block, Height},
    orchard::{Action, AuthorizedAction, Flags},
    parameters::{testnet::ConfiguredActivationHeights, Network, NetworkUpgrade},
    primitives::{ed25519, x25519, Groth16Proof},
    sapling,
    serialization::{AtLeastOne, DateTime32, ZcashDeserialize, ZcashDeserializeInto},
    sprout,
    transaction::{
        arbitrary::{
            insert_fake_orchard_shielded_data, test_transactions, transactions_from_blocks,
            v5_transactions,
        },
        zip317, Hash, HashType, JoinSplitData, LockTime, Transaction,
    },
    transparent::{self, CoinbaseData, CoinbaseSpendRestriction},
};

use zebra_node_services::mempool;
use zebra_state::ValidateContextError;
use zebra_test::mock_service::MockService;

use crate::{error::TransactionError, transaction::POLL_MEMPOOL_DELAY};

use super::{check, Request, Verifier};

#[cfg(test)]
mod prop;

/// Returns the timeout duration for tests, extended when running under coverage
/// instrumentation to account for the performance overhead.
fn test_timeout() -> std::time::Duration {
    // Check if we're running under cargo-llvm-cov by looking for its environment variables
    if std::env::var("LLVM_COV_FLAGS").is_ok() || std::env::var("CARGO_LLVM_COV").is_ok() {
        // Use a 5x longer timeout when running with coverage (150 seconds)
        std::time::Duration::from_secs(150)
    } else {
        std::time::Duration::from_secs(30)
    }
}

#[test]
fn v5_transactions_basic_check() -> Result<(), Report> {
    let _init_guard = zebra_test::init();

    for network in Network::iter() {
        for transaction in v5_transactions(network.block_iter()) {
            match check::has_inputs_and_outputs(&transaction) {
                Ok(()) => (),
                Err(TransactionError::NoInputs) | Err(TransactionError::NoOutputs) => (),
                Err(_) => panic!("error must be NoInputs or NoOutputs"),
            };

            // make sure there are no joinsplits nor spends in coinbase
            check::coinbase_tx_no_prevout_joinsplit_spend(&transaction)?;
        }
    }

    Ok(())
}

#[test]
fn v5_transaction_with_orchard_actions_has_inputs_and_outputs() {
    for net in Network::iter() {
        let mut tx = v5_transactions(net.block_iter())
            .find(|transaction| {
                transaction.inputs().is_empty()
                    && transaction.outputs().is_empty()
                    && transaction.sapling_spends_per_anchor().next().is_none()
                    && transaction.sapling_outputs().next().is_none()
                    && transaction.joinsplit_count() == 0
            })
            .expect("V5 tx with only Orchard shielded data");

        tx.orchard_shielded_data_mut().unwrap().flags = Flags::empty();

        // The check will fail if the transaction has no flags
        assert_eq!(
            check::has_inputs_and_outputs(&tx),
            Err(TransactionError::NoInputs)
        );

        // If we add ENABLE_SPENDS flag it will pass the inputs check but fails with the outputs
        tx.orchard_shielded_data_mut().unwrap().flags = Flags::ENABLE_SPENDS;

        assert_eq!(
            check::has_inputs_and_outputs(&tx),
            Err(TransactionError::NoOutputs)
        );

        // If we add ENABLE_OUTPUTS flag it will pass the outputs check but fails with the inputs
        tx.orchard_shielded_data_mut().unwrap().flags = Flags::ENABLE_OUTPUTS;

        assert_eq!(
            check::has_inputs_and_outputs(&tx),
            Err(TransactionError::NoInputs)
        );

        // Finally make it valid by adding both required flags
        tx.orchard_shielded_data_mut().unwrap().flags =
            Flags::ENABLE_SPENDS | Flags::ENABLE_OUTPUTS;

        assert!(check::has_inputs_and_outputs(&tx).is_ok());
    }
}

#[test]
fn v5_transaction_with_orchard_actions_has_flags() {
    for net in Network::iter() {
        let mut tx = v5_transactions(net.block_iter())
            .find(|transaction| {
                transaction.inputs().is_empty()
                    && transaction.outputs().is_empty()
                    && transaction.sapling_spends_per_anchor().next().is_none()
                    && transaction.sapling_outputs().next().is_none()
                    && transaction.joinsplit_count() == 0
            })
            .expect("V5 tx with only Orchard actions");

        tx.orchard_shielded_data_mut().unwrap().flags = Flags::empty();

        // The check will fail if the transaction has no flags
        assert_eq!(
            check::has_enough_orchard_flags(&tx),
            Err(TransactionError::NotEnoughFlags)
        );

        // If we add ENABLE_SPENDS flag it will pass.
        tx.orchard_shielded_data_mut().unwrap().flags = Flags::ENABLE_SPENDS;
        assert!(check::has_enough_orchard_flags(&tx).is_ok());

        tx.orchard_shielded_data_mut().unwrap().flags = Flags::empty();

        // If we add ENABLE_OUTPUTS flag instead, it will pass.
        tx.orchard_shielded_data_mut().unwrap().flags = Flags::ENABLE_OUTPUTS;
        assert!(check::has_enough_orchard_flags(&tx).is_ok());

        tx.orchard_shielded_data_mut().unwrap().flags = Flags::empty();

        // If we add BOTH ENABLE_SPENDS and ENABLE_OUTPUTS flags it will pass.
        tx.orchard_shielded_data_mut().unwrap().flags =
            Flags::ENABLE_SPENDS | Flags::ENABLE_OUTPUTS;
        assert!(check::has_enough_orchard_flags(&tx).is_ok());
    }
}

#[test]
fn v5_transaction_with_no_inputs_fails_verification() {
    let (_, output, _) = mock_transparent_transfer(
        Height(1),
        true,
        0,
        Amount::try_from(1).expect("valid value"),
    );

    for net in Network::iter() {
        let transaction = Transaction::V5 {
            inputs: vec![],
            outputs: vec![output.clone()],
            lock_time: LockTime::Height(block::Height(0)),
            expiry_height: NetworkUpgrade::Nu5.activation_height(&net).expect("height"),
            sapling_shielded_data: None,
            orchard_shielded_data: None,
            network_upgrade: NetworkUpgrade::Nu5,
        };

        assert_eq!(
            check::has_inputs_and_outputs(&transaction),
            Err(TransactionError::NoInputs)
        );
    }
}

#[test]
fn v5_transaction_with_no_outputs_fails_verification() {
    let (input, _, _) = mock_transparent_transfer(
        Height(1),
        true,
        0,
        Amount::try_from(1).expect("valid value"),
    );

    for net in Network::iter() {
        let transaction = Transaction::V5 {
            inputs: vec![input.clone()],
            outputs: vec![],
            lock_time: LockTime::Height(block::Height(0)),
            expiry_height: NetworkUpgrade::Nu5.activation_height(&net).expect("height"),
            sapling_shielded_data: None,
            orchard_shielded_data: None,
            network_upgrade: NetworkUpgrade::Nu5,
        };

        assert_eq!(
            check::has_inputs_and_outputs(&transaction),
            Err(TransactionError::NoOutputs)
        );
    }
}

#[tokio::test]
async fn mempool_request_with_missing_input_is_rejected() {
    let mut state: MockService<_, _, _, _> = MockService::build().for_unit_tests();

    for net in Network::iter() {
        let verifier = Verifier::new_for_tests(&net, state.clone());

        let (height, tx) = transactions_from_blocks(net.block_iter())
            .find(|(_, tx)| !(tx.is_coinbase() || tx.inputs().is_empty()))
            .expect(
                "At least one non-coinbase transaction with transparent inputs in test vectors",
            );

        let input_outpoint = match tx.inputs()[0] {
            transparent::Input::PrevOut { outpoint, .. } => outpoint,
            transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
        };

        // The first non-coinbase transaction with transparent inputs in our test vectors
        // does not use a lock time, so we don't see Request::BestChainNextMedianTimePast here

        let state_req = state
            .expect_request(zebra_state::Request::UnspentBestChainUtxo(input_outpoint))
            .map(|responder| responder.respond(zebra_state::Response::UnspentBestChainUtxo(None)));

        let verifier_req = verifier.oneshot(Request::Mempool {
            transaction: tx.into(),
            height,
        });

        let (rsp, _) = futures::join!(verifier_req, state_req);

        assert_eq!(rsp, Err(TransactionError::TransparentInputNotFound));
    }
}

#[tokio::test]
async fn mempool_request_with_present_input_is_accepted() {
    let mut state: MockService<_, _, _, _> = MockService::build().for_prop_tests();
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state.clone());

    let height = NetworkUpgrade::Canopy
        .activation_height(&Network::Mainnet)
        .expect("Canopy activation height is specified");
    let fund_height = (height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(10001).expect("invalid value"),
    );

    // Create a non-coinbase V4 tx with the last valid expiry height.
    let tx = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        expiry_height: height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let input_outpoint = match tx.inputs()[0] {
        transparent::Input::PrevOut { outpoint, .. } => outpoint,
        transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
    };

    tokio::spawn(async move {
        state
            .expect_request(zebra_state::Request::UnspentBestChainUtxo(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::UnspentBestChainUtxo(
                known_utxos
                    .get(&input_outpoint)
                    .map(|utxo| utxo.utxo.clone()),
            ));

        state
            .expect_request_that(|req| {
                matches!(
                    req,
                    zebra_state::Request::CheckBestChainTipNullifiersAndAnchors(_)
                )
            })
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::ValidBestChainTipNullifiersAndAnchors);
    });

    let verifier_response = verifier
        .oneshot(Request::Mempool {
            transaction: tx.into(),
            height,
        })
        .await;

    assert!(
        verifier_response.is_ok(),
        "expected successful verification, got: {verifier_response:?}"
    );
}

#[tokio::test]
async fn mempool_request_with_invalid_lock_time_is_rejected() {
    let mut state: MockService<_, _, _, _> = MockService::build().for_prop_tests();
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state.clone());

    let height = NetworkUpgrade::Canopy
        .activation_height(&Network::Mainnet)
        .expect("Canopy activation height is specified");
    let fund_height = (height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(1).expect("invalid value"),
    );

    // Create a non-coinbase V4 tx with the last valid expiry height.
    let tx = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::max_lock_time_timestamp(),
        expiry_height: height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let input_outpoint = match tx.inputs()[0] {
        transparent::Input::PrevOut { outpoint, .. } => outpoint,
        transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
    };

    tokio::spawn(async move {
        state
            .expect_request(zebra_state::Request::BestChainNextMedianTimePast)
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::BestChainNextMedianTimePast(
                DateTime32::from(
                    u32::try_from(LockTime::MIN_TIMESTAMP).expect("min time is valid"),
                ),
            ));

        state
            .expect_request(zebra_state::Request::UnspentBestChainUtxo(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::UnspentBestChainUtxo(
                known_utxos
                    .get(&input_outpoint)
                    .map(|utxo| utxo.utxo.clone()),
            ));

        state
            .expect_request_that(|req| {
                matches!(
                    req,
                    zebra_state::Request::CheckBestChainTipNullifiersAndAnchors(_)
                )
            })
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::ValidBestChainTipNullifiersAndAnchors);
    });

    let verifier_response = verifier
        .oneshot(Request::Mempool {
            transaction: tx.into(),
            height,
        })
        .await;

    assert_eq!(
        verifier_response,
        Err(TransactionError::LockedUntilAfterBlockTime(
            Utc.timestamp_opt(u32::MAX.into(), 0).unwrap()
        ))
    );
}

#[tokio::test]
async fn mempool_request_with_unlocked_lock_time_is_accepted() {
    let mut state: MockService<_, _, _, _> = MockService::build().for_prop_tests();
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state.clone());

    let height = NetworkUpgrade::Canopy
        .activation_height(&Network::Mainnet)
        .expect("Canopy activation height is specified");
    let fund_height = (height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(10001).expect("invalid value"),
    );

    // Create a non-coinbase V4 tx with the last valid expiry height.
    let tx = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        expiry_height: height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let input_outpoint = match tx.inputs()[0] {
        transparent::Input::PrevOut { outpoint, .. } => outpoint,
        transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
    };

    tokio::spawn(async move {
        state
            .expect_request(zebra_state::Request::UnspentBestChainUtxo(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::UnspentBestChainUtxo(
                known_utxos
                    .get(&input_outpoint)
                    .map(|utxo| utxo.utxo.clone()),
            ));

        state
            .expect_request_that(|req| {
                matches!(
                    req,
                    zebra_state::Request::CheckBestChainTipNullifiersAndAnchors(_)
                )
            })
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::ValidBestChainTipNullifiersAndAnchors);
    });

    let verifier_response = verifier
        .oneshot(Request::Mempool {
            transaction: tx.into(),
            height,
        })
        .await;

    assert!(
        verifier_response.is_ok(),
        "expected successful verification, got: {verifier_response:?}"
    );
}

#[tokio::test]
async fn mempool_request_with_lock_time_max_sequence_number_is_accepted() {
    let mut state: MockService<_, _, _, _> = MockService::build().for_prop_tests();
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state.clone());

    let height = NetworkUpgrade::Canopy
        .activation_height(&Network::Mainnet)
        .expect("Canopy activation height is specified");
    let fund_height = (height - 1).expect("fake source fund block height is too small");
    let (mut input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(10001).expect("invalid value"),
    );

    // Ignore the lock time.
    input.set_sequence(u32::MAX);

    // Create a non-coinbase V4 tx with the last valid expiry height.
    let tx = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::max_lock_time_timestamp(),
        expiry_height: height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let input_outpoint = match tx.inputs()[0] {
        transparent::Input::PrevOut { outpoint, .. } => outpoint,
        transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
    };

    tokio::spawn(async move {
        state
            .expect_request(zebra_state::Request::UnspentBestChainUtxo(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::UnspentBestChainUtxo(
                known_utxos
                    .get(&input_outpoint)
                    .map(|utxo| utxo.utxo.clone()),
            ));

        state
            .expect_request_that(|req| {
                matches!(
                    req,
                    zebra_state::Request::CheckBestChainTipNullifiersAndAnchors(_)
                )
            })
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::ValidBestChainTipNullifiersAndAnchors);
    });

    let verifier_response = verifier
        .oneshot(Request::Mempool {
            transaction: tx.into(),
            height,
        })
        .await;

    assert!(
        verifier_response.is_ok(),
        "expected successful verification, got: {verifier_response:?}"
    );
}

#[tokio::test]
async fn mempool_request_with_past_lock_time_is_accepted() {
    let mut state: MockService<_, _, _, _> = MockService::build().for_prop_tests();
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state.clone());

    let height = NetworkUpgrade::Canopy
        .activation_height(&Network::Mainnet)
        .expect("Canopy activation height is specified");
    let fund_height = (height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(10001).expect("invalid value"),
    );

    // Create a non-coinbase V4 tx with the last valid expiry height.
    let tx = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::min_lock_time_timestamp(),
        expiry_height: height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let input_outpoint = match tx.inputs()[0] {
        transparent::Input::PrevOut { outpoint, .. } => outpoint,
        transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
    };

    tokio::spawn(async move {
        state
            .expect_request(zebra_state::Request::BestChainNextMedianTimePast)
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::BestChainNextMedianTimePast(
                DateTime32::MAX,
            ));

        state
            .expect_request(zebra_state::Request::UnspentBestChainUtxo(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::UnspentBestChainUtxo(
                known_utxos
                    .get(&input_outpoint)
                    .map(|utxo| utxo.utxo.clone()),
            ));

        state
            .expect_request_that(|req| {
                matches!(
                    req,
                    zebra_state::Request::CheckBestChainTipNullifiersAndAnchors(_)
                )
            })
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::ValidBestChainTipNullifiersAndAnchors);
    });

    let verifier_response = verifier
        .oneshot(Request::Mempool {
            transaction: tx.into(),
            height,
        })
        .await;

    assert!(
        verifier_response.is_ok(),
        "expected successful verification, got: {verifier_response:?}"
    );
}

#[tokio::test]
async fn mempool_request_with_unmined_output_spends_is_accepted() {
    let mut state: MockService<_, _, _, _> = MockService::build().for_prop_tests();
    let mempool: MockService<_, _, _, _> = MockService::build().for_prop_tests();
    let (mempool_setup_tx, mempool_setup_rx) = tokio::sync::oneshot::channel();
    let verifier = Verifier::new(&Network::Mainnet, state.clone(), mempool_setup_rx);
    mempool_setup_tx
        .send(mempool.clone())
        .ok()
        .expect("send should succeed");

    let height = NetworkUpgrade::Canopy
        .activation_height(&Network::Mainnet)
        .expect("Canopy activation height is specified");
    let fund_height = (height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(10001).expect("invalid value"),
    );

    // Create a non-coinbase V4 tx with the last valid expiry height.
    let tx = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::min_lock_time_timestamp(),
        expiry_height: height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let input_outpoint = match tx.inputs()[0] {
        transparent::Input::PrevOut { outpoint, .. } => outpoint,
        transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
    };

    tokio::spawn(async move {
        state
            .expect_request(zebra_state::Request::BestChainNextMedianTimePast)
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::BestChainNextMedianTimePast(
                DateTime32::MAX,
            ));

        state
            .expect_request(zebra_state::Request::UnspentBestChainUtxo(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::UnspentBestChainUtxo(None));

        state
            .expect_request_that(|req| {
                matches!(
                    req,
                    zebra_state::Request::CheckBestChainTipNullifiersAndAnchors(_)
                )
            })
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::ValidBestChainTipNullifiersAndAnchors);
    });

    let mut mempool_clone = mempool.clone();
    tokio::spawn(async move {
        mempool_clone
            .expect_request(mempool::Request::AwaitOutput(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(mempool::Response::UnspentOutput(
                known_utxos
                    .get(&input_outpoint)
                    .expect("input outpoint should exist in known_utxos")
                    .utxo
                    .output
                    .clone(),
            ));
    });

    let verifier_response = verifier
        .oneshot(Request::Mempool {
            transaction: tx.into(),
            height,
        })
        .await;

    assert!(
        verifier_response.is_ok(),
        "expected successful verification, got: {verifier_response:?}"
    );

    let crate::transaction::Response::Mempool {
        transaction: _,
        spent_mempool_outpoints,
    } = verifier_response.expect("already checked that response is ok")
    else {
        panic!("unexpected response variant from transaction verifier for Mempool request")
    };

    assert_eq!(
        spent_mempool_outpoints,
        vec![input_outpoint],
        "spent_mempool_outpoints in tx verifier response should match input_outpoint"
    );

    tokio::time::sleep(POLL_MEMPOOL_DELAY * 2).await;
    // polled before AwaitOutput request and after a mempool transaction with transparent outputs
    // is successfully verified
    assert_eq!(
        mempool.poll_count(),
        2,
        "the mempool service should have been polled twice"
    );
}

#[tokio::test(flavor = "multi_thread")]
async fn skips_verification_of_block_transactions_in_mempool() {
    let mut state: MockService<_, _, _, _> = MockService::build().for_prop_tests();
    let mempool: MockService<_, _, _, _> = MockService::build().for_prop_tests();
    let (mempool_setup_tx, mempool_setup_rx) = tokio::sync::oneshot::channel();
    let verifier = Verifier::new(&Network::Mainnet, state.clone(), mempool_setup_rx);
    let verifier = Buffer::new(verifier, 1);

    mempool_setup_tx
        .send(mempool.clone())
        .ok()
        .expect("send should succeed");

    let height = NetworkUpgrade::Nu6
        .activation_height(&Network::Mainnet)
        .expect("Canopy activation height is specified");
    let fund_height = (height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(10001).expect("invalid value"),
    );

    // Create a non-coinbase V4 tx with the last valid expiry height.
    let tx = Transaction::V5 {
        network_upgrade: NetworkUpgrade::Nu6,
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::min_lock_time_timestamp(),
        expiry_height: height,
        sapling_shielded_data: None,
        orchard_shielded_data: None,
    };

    let tx_hash = tx.hash();
    let input_outpoint = match tx.inputs()[0] {
        transparent::Input::PrevOut { outpoint, .. } => outpoint,
        transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
    };

    let mut state_clone = state.clone();
    tokio::spawn(async move {
        state_clone
            .expect_request(zebra_state::Request::BestChainNextMedianTimePast)
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::BestChainNextMedianTimePast(
                DateTime32::MAX,
            ));

        state_clone
            .expect_request(zebra_state::Request::UnspentBestChainUtxo(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::UnspentBestChainUtxo(None));

        state_clone
            .expect_request_that(|req| {
                matches!(
                    req,
                    zebra_state::Request::CheckBestChainTipNullifiersAndAnchors(_)
                )
            })
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::ValidBestChainTipNullifiersAndAnchors);
    });

    let utxo = known_utxos
        .get(&input_outpoint)
        .expect("input outpoint should exist in known_utxos")
        .utxo
        .clone();

    let mut mempool_clone = mempool.clone();
    let output = utxo.output.clone();
    tokio::spawn(async move {
        mempool_clone
            .expect_request(mempool::Request::AwaitOutput(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(mempool::Response::UnspentOutput(output));
    });

    // Briefly yield and sleep so the spawned task can first expect an await output request.
    tokio::time::sleep(std::time::Duration::from_millis(10)).await;

    let verifier_response = verifier
        .clone()
        .oneshot(Request::Mempool {
            transaction: tx.clone().into(),
            height,
        })
        .await;

    assert!(
        verifier_response.is_ok(),
        "expected successful verification, got: {verifier_response:?}"
    );

    let crate::transaction::Response::Mempool {
        transaction,
        spent_mempool_outpoints,
    } = verifier_response.expect("already checked that response is ok")
    else {
        panic!("unexpected response variant from transaction verifier for Mempool request")
    };

    assert_eq!(
        spent_mempool_outpoints,
        vec![input_outpoint],
        "spent_mempool_outpoints in tx verifier response should match input_outpoint"
    );

    let mut mempool_clone = mempool.clone();
    tokio::spawn(async move {
        for _ in 0..2 {
            mempool_clone
                .expect_request(mempool::Request::TransactionWithDepsByMinedId(tx_hash))
                .await
                .expect("verifier should call mock mempool service with correct request")
                .respond(mempool::Response::TransactionWithDeps {
                    transaction: transaction.clone(),
                    dependencies: [input_outpoint.hash].into(),
                });
        }
    });

    let make_request = |known_outpoint_hashes| Request::Block {
        transaction_hash: tx_hash,
        transaction: Arc::new(tx),
        known_outpoint_hashes,
        known_utxos: Arc::new(HashMap::new()),
        height,
        time: Utc::now(),
    };

    // Briefly yield and sleep so the spawned task can first expect the requests.
    tokio::time::sleep(std::time::Duration::from_millis(10)).await;

    let crate::transaction::Response::Block { .. } = verifier
        .clone()
        .oneshot(make_request.clone()(Arc::new([input_outpoint.hash].into())))
        .await
        .expect("should return Ok without calling state service")
    else {
        panic!("unexpected response variant from transaction verifier for Block request")
    };

    tokio::spawn(async move {
        state
            .expect_request(zebra_state::Request::AwaitUtxo(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::Utxo(utxo));
    });

    let crate::transaction::Response::Block { .. } = verifier
        .clone()
        .oneshot(make_request.clone()(Arc::new(HashSet::new())))
        .await
        .expect("should succeed after calling state service")
    else {
        panic!("unexpected response variant from transaction verifier for Block request")
    };

    tokio::time::sleep(POLL_MEMPOOL_DELAY * 2).await;
    // polled before AwaitOutput request, after a mempool transaction with transparent outputs,
    // is successfully verified, and twice more when checking if a transaction in a block is
    // already the mempool.
    assert_eq!(
        mempool.poll_count(),
        4,
        "the mempool service should have been polled 4 times"
    );
}

/// Tests that calls to the transaction verifier with a mempool request that spends
/// immature coinbase outputs will return an error.
#[tokio::test]
async fn mempool_request_with_immature_spend_is_rejected() {
    let _init_guard = zebra_test::init();

    let mut state: MockService<_, _, _, _> = MockService::build().for_prop_tests();
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state.clone());

    let height = NetworkUpgrade::Canopy
        .activation_height(&Network::Mainnet)
        .expect("Canopy activation height is specified");
    let fund_height = (height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(10001).expect("invalid value"),
    );

    // Create a non-coinbase V4 tx with the last valid expiry height.
    let tx = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::min_lock_time_timestamp(),
        expiry_height: height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let input_outpoint = match tx.inputs()[0] {
        transparent::Input::PrevOut { outpoint, .. } => outpoint,
        transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
    };

    let spend_restriction = tx.coinbase_spend_restriction(&Network::Mainnet, height);

    let coinbase_spend_height = Height(5);

    let utxo = known_utxos
        .get(&input_outpoint)
        .map(|utxo| {
            let mut utxo = utxo.utxo.clone();
            utxo.height = coinbase_spend_height;
            utxo.from_coinbase = true;
            utxo
        })
        .expect("known_utxos should contain the outpoint");

    let expected_error =
        zebra_state::check::transparent_coinbase_spend(input_outpoint, spend_restriction, &utxo)
            .map_err(Box::new)
            .map_err(TransactionError::ValidateContextError)
            .expect_err("check should fail");

    tokio::spawn(async move {
        state
            .expect_request(zebra_state::Request::BestChainNextMedianTimePast)
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::BestChainNextMedianTimePast(
                DateTime32::MAX,
            ));

        state
            .expect_request(zebra_state::Request::UnspentBestChainUtxo(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::UnspentBestChainUtxo(
                known_utxos.get(&input_outpoint).map(|utxo| {
                    let mut utxo = utxo.utxo.clone();
                    utxo.height = coinbase_spend_height;
                    utxo.from_coinbase = true;
                    utxo
                }),
            ));

        state
            .expect_request_that(|req| {
                matches!(
                    req,
                    zebra_state::Request::CheckBestChainTipNullifiersAndAnchors(_)
                )
            })
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::ValidBestChainTipNullifiersAndAnchors);
    });

    let verifier_response = verifier
        .oneshot(Request::Mempool {
            transaction: tx.into(),
            height,
        })
        .await
        .expect_err("verification of transaction with immature spend should fail");

    assert_eq!(
        verifier_response, expected_error,
        "expected to fail verification, got: {verifier_response:?}"
    );
}

/// Tests that calls to the transaction verifier with a mempool request that spends
/// mature coinbase outputs to transparent outputs will return Ok() on Regtest.
#[tokio::test]
async fn mempool_request_with_transparent_coinbase_spend_is_accepted_on_regtest() {
    let _init_guard = zebra_test::init();

    let network = Network::new_regtest(
        ConfiguredActivationHeights {
            canopy: Some(1),
            nu5: Some(100),
            nu6: Some(1_000),
            ..Default::default()
        }
        .into(),
    );
    let mut state: MockService<_, _, _, _> = MockService::build().for_unit_tests();
    let verifier = Verifier::new_for_tests(&network, state.clone());

    let height = NetworkUpgrade::Nu6
        .activation_height(&network)
        .expect("NU6 activation height is specified");
    let fund_height = (height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(10001).expect("invalid value"),
    );

    // Create a non-coinbase V5 tx with the last valid expiry height.
    let tx = Transaction::V5 {
        network_upgrade: NetworkUpgrade::Nu6,
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::min_lock_time_timestamp(),
        expiry_height: height,
        sapling_shielded_data: None,
        orchard_shielded_data: None,
    };

    let input_outpoint = match tx.inputs()[0] {
        transparent::Input::PrevOut { outpoint, .. } => outpoint,
        transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
    };

    let spend_restriction = tx.coinbase_spend_restriction(&network, height);

    assert_eq!(
        spend_restriction,
        CoinbaseSpendRestriction::CheckCoinbaseMaturity {
            spend_height: height
        }
    );

    let coinbase_spend_height = Height(5);

    let utxo = known_utxos
        .get(&input_outpoint)
        .map(|utxo| {
            let mut utxo = utxo.utxo.clone();
            utxo.height = coinbase_spend_height;
            utxo.from_coinbase = true;
            utxo
        })
        .expect("known_utxos should contain the outpoint");

    zebra_state::check::transparent_coinbase_spend(input_outpoint, spend_restriction, &utxo)
        .expect("check should pass");

    tokio::spawn(async move {
        state
            .expect_request(zebra_state::Request::BestChainNextMedianTimePast)
            .await
            .respond(zebra_state::Response::BestChainNextMedianTimePast(
                DateTime32::MAX,
            ));

        state
            .expect_request(zebra_state::Request::UnspentBestChainUtxo(input_outpoint))
            .await
            .respond(zebra_state::Response::UnspentBestChainUtxo(Some(utxo)));

        state
            .expect_request_that(|req| {
                matches!(
                    req,
                    zebra_state::Request::CheckBestChainTipNullifiersAndAnchors(_)
                )
            })
            .await
            .respond(zebra_state::Response::ValidBestChainTipNullifiersAndAnchors);
    });

    verifier
        .oneshot(Request::Mempool {
            transaction: tx.into(),
            height,
        })
        .await
        .expect("verification of transaction with mature spend to transparent outputs should pass");
}

/// Tests that errors from the read state service are correctly converted into
/// transaction verifier errors.
#[tokio::test]
async fn state_error_converted_correctly() {
    use zebra_state::DuplicateNullifierError;

    let mut state: MockService<_, _, _, _> = MockService::build().for_prop_tests();
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state.clone());

    let height = NetworkUpgrade::Canopy
        .activation_height(&Network::Mainnet)
        .expect("Canopy activation height is specified");
    let fund_height = (height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(10001).expect("invalid value"),
    );

    // Create a non-coinbase V4 tx with the last valid expiry height.
    let tx = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        expiry_height: height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let input_outpoint = match tx.inputs()[0] {
        transparent::Input::PrevOut { outpoint, .. } => outpoint,
        transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
    };

    let make_validate_context_error =
        || sprout::Nullifier([0; 32].into()).duplicate_nullifier_error(true);

    tokio::spawn(async move {
        state
            .expect_request(zebra_state::Request::UnspentBestChainUtxo(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::UnspentBestChainUtxo(
                known_utxos
                    .get(&input_outpoint)
                    .map(|utxo| utxo.utxo.clone()),
            ));

        state
            .expect_request_that(|req| {
                matches!(
                    req,
                    zebra_state::Request::CheckBestChainTipNullifiersAndAnchors(_)
                )
            })
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(Err::<zebra_state::Response, zebra_state::BoxError>(
                make_validate_context_error().into(),
            ));
    });

    let verifier_response = verifier
        .oneshot(Request::Mempool {
            transaction: tx.into(),
            height,
        })
        .await;

    let transaction_error =
        verifier_response.expect_err("expected failed verification, got: {verifier_response:?}");

    assert_eq!(
        TransactionError::from(make_validate_context_error()),
        transaction_error,
        "expected matching state and transaction errors"
    );

    let state_error = zebra_state::BoxError::from(make_validate_context_error())
        .downcast::<ValidateContextError>()
        .map(|boxed| TransactionError::from(*boxed))
        .expect("downcast should succeed");

    assert_eq!(
        state_error, transaction_error,
        "expected matching state and transaction errors"
    );

    let TransactionError::ValidateContextError(propagated_validate_context_error) =
        transaction_error
    else {
        panic!("should be a ValidateContextError variant");
    };

    assert_eq!(
        *propagated_validate_context_error,
        make_validate_context_error(),
        "expected matching state and transaction errors"
    );
}

#[test]
fn v5_coinbase_transaction_without_enable_spends_flag_passes_validation() {
    for net in Network::iter() {
        let mut tx = v5_transactions(net.block_iter())
            .find(|transaction| transaction.is_coinbase())
            .expect("V5 coinbase tx");

        let shielded_data = insert_fake_orchard_shielded_data(&mut tx);

        assert!(!shielded_data.flags.contains(Flags::ENABLE_SPENDS));

        assert!(check::coinbase_tx_no_prevout_joinsplit_spend(&tx).is_ok());
    }
}

#[test]
fn v5_coinbase_transaction_with_enable_spends_flag_fails_validation() {
    for net in Network::iter() {
        let mut tx = v5_transactions(net.block_iter())
            .find(|transaction| transaction.is_coinbase())
            .expect("V5 coinbase tx");

        let shielded_data = insert_fake_orchard_shielded_data(&mut tx);

        assert!(!shielded_data.flags.contains(Flags::ENABLE_SPENDS));

        shielded_data.flags = Flags::ENABLE_SPENDS;

        assert_eq!(
            check::coinbase_tx_no_prevout_joinsplit_spend(&tx),
            Err(TransactionError::CoinbaseHasEnableSpendsOrchard)
        );
    }
}

#[tokio::test]
async fn v5_transaction_is_rejected_before_nu5_activation() {
    let sapling = NetworkUpgrade::Sapling;

    for net in Network::iter() {
        let verifier = Verifier::new_for_tests(
            &net,
            service_fn(|_| async { unreachable!("Service should not be called") }),
        );

        let tx = v5_transactions(net.block_iter()).next().expect("V5 tx");

        assert_eq!(
            verifier
                .oneshot(Request::Block {
                    transaction_hash: tx.hash(),
                    transaction: Arc::new(tx),
                    known_utxos: Arc::new(HashMap::new()),
                    known_outpoint_hashes: Arc::new(HashSet::new()),
                    height: sapling.activation_height(&net).expect("height"),
                    time: DateTime::<Utc>::MAX_UTC,
                })
                .await,
            Err(TransactionError::UnsupportedByNetworkUpgrade(5, sapling))
        );
    }
}

#[tokio::test]
async fn v5_transaction_is_accepted_after_nu5_activation() {
    let _init_guard = zebra_test::init();

    for net in Network::iter() {
        let state = service_fn(|_| async { unreachable!("Service should not be called") });
        let tx = v5_transactions(net.block_iter()).next().expect("V5 tx");
        let tx_height = tx.expiry_height().expect("V5 must have expiry_height");
        let expected = tx.unmined_id();

        assert!(tx_height >= NetworkUpgrade::Nu5.activation_height(&net).expect("height"));

        let verif_res = Verifier::new_for_tests(&net, state)
            .oneshot(Request::Block {
                transaction_hash: tx.hash(),
                transaction: Arc::new(tx),
                known_utxos: Arc::new(HashMap::new()),
                known_outpoint_hashes: Arc::new(HashSet::new()),
                height: tx_height,
                time: DateTime::<Utc>::MAX_UTC,
            })
            .await;

        assert_eq!(verif_res.expect("success").tx_id(), expected);
    }
}

/// Test if V4 transaction with transparent funds is accepted.
#[tokio::test]
async fn v4_transaction_with_transparent_transfer_is_accepted() {
    let network = Network::Mainnet;

    let canopy_activation_height = NetworkUpgrade::Canopy
        .activation_height(&network)
        .expect("Canopy activation height is specified");

    let transaction_block_height =
        (canopy_activation_height + 10).expect("transaction block height is too large");

    let fake_source_fund_height =
        (transaction_block_height - 1).expect("fake source fund block height is too small");

    // Create a fake transparent transfer that should succeed
    let (input, output, known_utxos) = mock_transparent_transfer(
        fake_source_fund_height,
        true,
        0,
        Amount::try_from(1).expect("invalid value"),
    );

    // Create a V4 transaction
    let transaction = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::Height(block::Height(0)),
        expiry_height: (transaction_block_height + 1).expect("expiry height is too large"),
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let transaction_hash = transaction.unmined_id();

    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&network, state_service);

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction),
            known_utxos: Arc::new(known_utxos),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: transaction_block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result.expect("unexpected error response").tx_id(),
        transaction_hash
    );
}

/// Tests if a non-coinbase V4 transaction with the last valid expiry height is
/// accepted.
#[tokio::test]
async fn v4_transaction_with_last_valid_expiry_height() {
    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state_service);

    let block_height = NetworkUpgrade::Canopy
        .activation_height(&Network::Mainnet)
        .expect("Canopy activation height is specified");
    let fund_height = (block_height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(1).expect("invalid value"),
    );

    // Create a non-coinbase V4 tx with the last valid expiry height.
    let transaction = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        expiry_height: block_height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction.clone()),
            known_utxos: Arc::new(known_utxos),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result.expect("unexpected error response").tx_id(),
        transaction.unmined_id()
    );
}

/// Tests if a coinbase V4 transaction with an expiry height lower than the
/// block height is accepted.
///
/// Note that an expiry height lower than the block height is considered
/// *expired* for *non-coinbase* transactions.
#[tokio::test]
async fn v4_coinbase_transaction_with_low_expiry_height() {
    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state_service);

    let block_height = NetworkUpgrade::Canopy
        .activation_height(&Network::Mainnet)
        .expect("Canopy activation height is specified");

    let (input, output) = mock_coinbase_transparent_output(block_height);

    // This is a correct expiry height for coinbase V4 transactions.
    let expiry_height = (block_height - 1).expect("original block height is too small");

    // Create a coinbase V4 tx.
    let transaction = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        expiry_height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction.clone()),
            known_utxos: Arc::new(HashMap::new()),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result.expect("unexpected error response").tx_id(),
        transaction.unmined_id()
    );
}

/// Tests if an expired non-coinbase V4 transaction is rejected.
#[tokio::test]
async fn v4_transaction_with_too_low_expiry_height() {
    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state_service);

    let block_height = NetworkUpgrade::Canopy
        .activation_height(&Network::Mainnet)
        .expect("Canopy activation height is specified");

    let fund_height = (block_height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(1).expect("invalid value"),
    );

    // This expiry height is too low so that the tx should seem expired to the verifier.
    let expiry_height = (block_height - 1).expect("original block height is too small");

    // Create a non-coinbase V4 tx.
    let transaction = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        expiry_height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction.clone()),
            known_utxos: Arc::new(known_utxos),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result,
        Err(TransactionError::ExpiredTransaction {
            expiry_height,
            block_height,
            transaction_hash: transaction.hash(),
        })
    );
}

/// Tests if a non-coinbase V4 transaction with an expiry height exceeding the
/// maximum is rejected.
#[tokio::test]
async fn v4_transaction_with_exceeding_expiry_height() {
    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state_service);

    let block_height = block::Height::MAX;

    let fund_height = (block_height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(1).expect("invalid value"),
    );

    // This expiry height exceeds the maximum defined by the specification.
    let expiry_height = block::Height(500_000_000);

    // Create a non-coinbase V4 tx.
    let transaction = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        expiry_height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction.clone()),
            known_utxos: Arc::new(known_utxos),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result,
        Err(TransactionError::MaximumExpiryHeight {
            expiry_height,
            is_coinbase: false,
            block_height,
            transaction_hash: transaction.hash(),
        })
    );
}

/// Tests if a coinbase V4 transaction with an expiry height exceeding the
/// maximum is rejected.
#[tokio::test]
async fn v4_coinbase_transaction_with_exceeding_expiry_height() {
    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state_service);

    // Use an arbitrary pre-NU5 block height.
    // It can't be NU5-onward because the expiry height limit is not enforced
    // for coinbase transactions (it needs to match the block height instead),
    // which is what is used in this test.
    let block_height = (NetworkUpgrade::Nu5
        .activation_height(&Network::Mainnet)
        .expect("NU5 height must be set")
        - 1)
    .expect("will not underflow");

    let (input, output) = mock_coinbase_transparent_output(block_height);

    // This expiry height exceeds the maximum defined by the specification.
    let expiry_height = block::Height(500_000_000);

    // Create a coinbase V4 tx.
    let transaction = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        expiry_height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction.clone()),
            known_utxos: Arc::new(HashMap::new()),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result,
        Err(TransactionError::MaximumExpiryHeight {
            expiry_height,
            is_coinbase: true,
            block_height,
            transaction_hash: transaction.hash(),
        })
    );
}

/// Test if V4 coinbase transaction is accepted.
#[tokio::test]
async fn v4_coinbase_transaction_is_accepted() {
    let network = Network::Mainnet;

    let canopy_activation_height = NetworkUpgrade::Canopy
        .activation_height(&network)
        .expect("Canopy activation height is specified");

    let transaction_block_height =
        (canopy_activation_height + 10).expect("transaction block height is too large");

    // Create a fake transparent coinbase that should succeed
    let (input, output) = mock_coinbase_transparent_output(transaction_block_height);

    // Create a V4 coinbase transaction
    let transaction = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::Height(block::Height(0)),
        expiry_height: transaction_block_height,
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let transaction_hash = transaction.unmined_id();

    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&network, state_service);

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction),
            known_utxos: Arc::new(HashMap::new()),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: transaction_block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result.expect("unexpected error response").tx_id(),
        transaction_hash
    );
}

/// Test if V4 transaction with transparent funds is rejected if the source script prevents it.
///
/// This test simulates the case where the script verifier rejects the transaction because the
/// script prevents spending the source UTXO.
#[tokio::test]
async fn v4_transaction_with_transparent_transfer_is_rejected_by_the_script() {
    let network = Network::Mainnet;

    let canopy_activation_height = NetworkUpgrade::Canopy
        .activation_height(&network)
        .expect("Canopy activation height is specified");

    let transaction_block_height =
        (canopy_activation_height + 10).expect("transaction block height is too large");

    let fake_source_fund_height =
        (transaction_block_height - 1).expect("fake source fund block height is too small");

    // Create a fake transparent transfer that should not succeed
    let (input, output, known_utxos) = mock_transparent_transfer(
        fake_source_fund_height,
        false,
        0,
        Amount::try_from(1).expect("invalid value"),
    );

    // Create a V4 transaction
    let transaction = Transaction::V4 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::Height(block::Height(0)),
        expiry_height: (transaction_block_height + 1).expect("expiry height is too large"),
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&network, state_service);

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction),
            known_utxos: Arc::new(known_utxos),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: transaction_block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result,
        Err(TransactionError::InternalDowncastError(
            "downcast to known transaction error type failed, original error: ScriptInvalid"
                .to_string()
        ))
    );
}

/// Test if V4 transaction with an internal double spend of transparent funds is rejected.
#[tokio::test]
async fn v4_transaction_with_conflicting_transparent_spend_is_rejected() {
    let network = Network::Mainnet;

    let canopy_activation_height = NetworkUpgrade::Canopy
        .activation_height(&network)
        .expect("Canopy activation height is specified");

    let transaction_block_height =
        (canopy_activation_height + 10).expect("transaction block height is too large");

    let fake_source_fund_height =
        (transaction_block_height - 1).expect("fake source fund block height is too small");

    // Create a fake transparent transfer that should succeed
    let (input, output, known_utxos) = mock_transparent_transfer(
        fake_source_fund_height,
        true,
        0,
        Amount::try_from(1).expect("invalid value"),
    );

    // Create a V4 transaction
    let transaction = Transaction::V4 {
        inputs: vec![input.clone(), input.clone()],
        outputs: vec![output],
        lock_time: LockTime::Height(block::Height(0)),
        expiry_height: (transaction_block_height + 1).expect("expiry height is too large"),
        joinsplit_data: None,
        sapling_shielded_data: None,
    };

    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&network, state_service);

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction),
            known_utxos: Arc::new(known_utxos),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: transaction_block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    let expected_outpoint = input.outpoint().expect("Input should have an outpoint");

    assert_eq!(
        result,
        Err(TransactionError::DuplicateTransparentSpend(
            expected_outpoint
        ))
    );
}

/// Test if V4 transaction with a joinsplit that has duplicate nullifiers is rejected.
#[test]
fn v4_transaction_with_conflicting_sprout_nullifier_inside_joinsplit_is_rejected() {
    let _init_guard = zebra_test::init();
    zebra_test::MULTI_THREADED_RUNTIME.block_on(async {
        let network = Network::Mainnet;
        let nu = NetworkUpgrade::Canopy;

        let canopy_activation_height = NetworkUpgrade::Canopy
            .activation_height(&network)
            .expect("Canopy activation height is specified");

        let transaction_block_height =
            (canopy_activation_height + 10).expect("transaction block height is too large");

        // Create a fake Sprout join split
        let (mut joinsplit_data, signing_key) = mock_sprout_join_split_data();

        // Make both nullifiers the same inside the joinsplit transaction
        let duplicate_nullifier = joinsplit_data.first.nullifiers[0];
        joinsplit_data.first.nullifiers[1] = duplicate_nullifier;

        // Create a V4 transaction
        let mut transaction = Transaction::V4 {
            inputs: vec![],
            outputs: vec![],
            lock_time: LockTime::Height(block::Height(0)),
            expiry_height: (transaction_block_height + 1).expect("expiry height is too large"),
            joinsplit_data: Some(joinsplit_data),
            sapling_shielded_data: None,
        };

        // Sign the transaction
        let sighash = transaction
            .sighash(nu, HashType::ALL, Arc::new(Vec::new()), None)
            .expect("network upgrade should be valid for tx");

        match &mut transaction {
            Transaction::V4 {
                joinsplit_data: Some(joinsplit_data),
                ..
            } => joinsplit_data.sig = signing_key.sign(sighash.as_ref()),
            _ => unreachable!("Mock transaction was created incorrectly"),
        }

        let state_service =
            service_fn(|_| async { unreachable!("State service should not be called") });
        let verifier = Verifier::new_for_tests(&network, state_service);

        let result = verifier
            .oneshot(Request::Block {
                transaction_hash: transaction.hash(),
                transaction: Arc::new(transaction),
                known_utxos: Arc::new(HashMap::new()),
                known_outpoint_hashes: Arc::new(HashSet::new()),
                height: transaction_block_height,
                time: DateTime::<Utc>::MAX_UTC,
            })
            .await;

        assert_eq!(
            result,
            Err(TransactionError::DuplicateSproutNullifier(
                duplicate_nullifier
            ))
        );
    });
}

/// Test if V4 transaction with duplicate nullifiers across joinsplits is rejected.
#[test]
fn v4_transaction_with_conflicting_sprout_nullifier_across_joinsplits_is_rejected() {
    let _init_guard = zebra_test::init();
    zebra_test::MULTI_THREADED_RUNTIME.block_on(async {
        let network = Network::Mainnet;
        let nu = NetworkUpgrade::Canopy;

        let canopy_activation_height = NetworkUpgrade::Canopy
            .activation_height(&network)
            .expect("Canopy activation height is specified");

        let transaction_block_height =
            (canopy_activation_height + 10).expect("transaction block height is too large");

        // Create a fake Sprout join split
        let (mut joinsplit_data, signing_key) = mock_sprout_join_split_data();

        // Duplicate a nullifier from the created joinsplit
        let duplicate_nullifier = joinsplit_data.first.nullifiers[1];

        // Add a new joinsplit with the duplicate nullifier
        let mut new_joinsplit = joinsplit_data.first.clone();
        new_joinsplit.nullifiers[0] = duplicate_nullifier;
        new_joinsplit.nullifiers[1] = sprout::note::Nullifier([2u8; 32].into());

        joinsplit_data.rest.push(new_joinsplit);

        // Create a V4 transaction
        let mut transaction = Transaction::V4 {
            inputs: vec![],
            outputs: vec![],
            lock_time: LockTime::Height(block::Height(0)),
            expiry_height: (transaction_block_height + 1).expect("expiry height is too large"),
            joinsplit_data: Some(joinsplit_data),
            sapling_shielded_data: None,
        };

        // Sign the transaction
        let sighash = transaction
            .sighash(nu, HashType::ALL, Arc::new(Vec::new()), None)
            .expect("network upgrade should be valid for tx");

        match &mut transaction {
            Transaction::V4 {
                joinsplit_data: Some(joinsplit_data),
                ..
            } => joinsplit_data.sig = signing_key.sign(sighash.as_ref()),
            _ => unreachable!("Mock transaction was created incorrectly"),
        }

        let state_service =
            service_fn(|_| async { unreachable!("State service should not be called") });
        let verifier = Verifier::new_for_tests(&network, state_service);

        let result = verifier
            .oneshot(Request::Block {
                transaction_hash: transaction.hash(),
                transaction: Arc::new(transaction),
                known_utxos: Arc::new(HashMap::new()),
                known_outpoint_hashes: Arc::new(HashSet::new()),
                height: transaction_block_height,
                time: DateTime::<Utc>::MAX_UTC,
            })
            .await;

        assert_eq!(
            result,
            Err(TransactionError::DuplicateSproutNullifier(
                duplicate_nullifier
            ))
        );
    });
}

/// Test if V5 transaction with transparent funds is accepted.
#[tokio::test]
async fn v5_transaction_with_transparent_transfer_is_accepted() {
    let network = Network::new_default_testnet();
    let network_upgrade = NetworkUpgrade::Nu5;

    let nu5_activation_height = network_upgrade
        .activation_height(&network)
        .expect("NU5 activation height is specified");

    let transaction_block_height =
        (nu5_activation_height + 10).expect("transaction block height is too large");

    let fake_source_fund_height =
        (transaction_block_height - 1).expect("fake source fund block height is too small");

    // Create a fake transparent transfer that should succeed
    let (input, output, known_utxos) = mock_transparent_transfer(
        fake_source_fund_height,
        true,
        0,
        Amount::try_from(1).expect("invalid value"),
    );

    // Create a V5 transaction
    let transaction = Transaction::V5 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::Height(block::Height(0)),
        expiry_height: (transaction_block_height + 1).expect("expiry height is too large"),
        sapling_shielded_data: None,
        orchard_shielded_data: None,
        network_upgrade,
    };

    let transaction_hash = transaction.unmined_id();

    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&network, state_service);

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction),
            known_utxos: Arc::new(known_utxos),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: transaction_block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result.expect("unexpected error response").tx_id(),
        transaction_hash
    );
}

/// Tests if a non-coinbase V5 transaction with the last valid expiry height is
/// accepted.
#[tokio::test]
async fn v5_transaction_with_last_valid_expiry_height() {
    let network = Network::new_default_testnet();
    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&network, state_service);

    let block_height = NetworkUpgrade::Nu5
        .activation_height(&network)
        .expect("Nu5 activation height for testnet is specified");
    let fund_height = (block_height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(1).expect("invalid value"),
    );

    // Create a non-coinbase V5 tx with the last valid expiry height.
    let transaction = Transaction::V5 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        expiry_height: block_height,
        sapling_shielded_data: None,
        orchard_shielded_data: None,
        network_upgrade: NetworkUpgrade::Nu5,
    };

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction.clone()),
            known_utxos: Arc::new(known_utxos),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result.expect("unexpected error response").tx_id(),
        transaction.unmined_id()
    );
}

/// Tests that a coinbase V5 transaction is accepted only if its expiry height
/// is equal to the height of the block the transaction belongs to.
#[tokio::test]
async fn v5_coinbase_transaction_expiry_height() {
    let network = Network::new_default_testnet();
    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&network, state_service);
    let verifier = Buffer::new(verifier, 10);

    let block_height = NetworkUpgrade::Nu5
        .activation_height(&network)
        .expect("Nu5 activation height for testnet is specified");

    let (input, output) = mock_coinbase_transparent_output(block_height);

    // Create a coinbase V5 tx with an expiry height that matches the height of
    // the block. Note that this is the only valid expiry height for a V5
    // coinbase tx.
    let transaction = Transaction::V5 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        expiry_height: block_height,
        sapling_shielded_data: None,
        orchard_shielded_data: None,
        network_upgrade: NetworkUpgrade::Nu5,
    };

    let result = verifier
        .clone()
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction.clone()),
            known_utxos: Arc::new(HashMap::new()),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result.expect("unexpected error response").tx_id(),
        transaction.unmined_id()
    );

    // Increment the expiry height so that it becomes invalid.
    let new_expiry_height = (block_height + 1).expect("transaction block height is too large");
    let mut new_transaction = transaction.clone();

    *new_transaction.expiry_height_mut() = new_expiry_height;

    let result = verifier
        .clone()
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(new_transaction.clone()),
            known_utxos: Arc::new(HashMap::new()),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await
        .map_err(|err| {
            *err.downcast()
                .expect("error type should be TransactionError")
        });

    assert_eq!(
        result,
        Err(TransactionError::CoinbaseExpiryBlockHeight {
            expiry_height: Some(new_expiry_height),
            block_height,
            transaction_hash: new_transaction.hash(),
        })
    );

    // Decrement the expiry height so that it becomes invalid.
    let new_expiry_height = (block_height - 1).expect("transaction block height is too low");
    let mut new_transaction = transaction.clone();

    *new_transaction.expiry_height_mut() = new_expiry_height;

    let result = verifier
        .clone()
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(new_transaction.clone()),
            known_utxos: Arc::new(HashMap::new()),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await
        .map_err(|err| {
            *err.downcast()
                .expect("error type should be TransactionError")
        });

    assert_eq!(
        result,
        Err(TransactionError::CoinbaseExpiryBlockHeight {
            expiry_height: Some(new_expiry_height),
            block_height,
            transaction_hash: new_transaction.hash(),
        })
    );

    // Test with matching heights again, but using a very high value
    // that is greater than the limit for non-coinbase transactions,
    // to ensure the limit is not being enforced for coinbase transactions.
    let new_expiry_height = Height::MAX;
    let mut new_transaction = transaction.clone();

    *new_transaction.expiry_height_mut() = new_expiry_height;

    // Setting the new expiry height as the block height will activate NU6, so we need to set NU6
    // for the tx as well.
    let height = new_expiry_height;
    new_transaction
        .update_network_upgrade(NetworkUpgrade::current(&network, height))
        .expect("updating the network upgrade for a V5 tx should succeed");

    let verification_result = verifier
        .clone()
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(new_transaction.clone()),
            known_utxos: Arc::new(HashMap::new()),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        verification_result
            .expect("successful verification")
            .tx_id(),
        new_transaction.unmined_id()
    );
}

/// Tests if an expired non-coinbase V5 transaction is rejected.
#[tokio::test]
async fn v5_transaction_with_too_low_expiry_height() {
    let network = Network::new_default_testnet();

    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&network, state_service);

    let block_height = NetworkUpgrade::Nu5
        .activation_height(&network)
        .expect("Nu5 activation height for testnet is specified");
    let fund_height = (block_height - 1).expect("fake source fund block height is too small");
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(1).expect("invalid value"),
    );

    // This expiry height is too low so that the tx should seem expired to the verifier.
    let expiry_height = (block_height - 1).expect("original block height is too small");

    // Create a non-coinbase V5 tx.
    let transaction = Transaction::V5 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        expiry_height,
        sapling_shielded_data: None,
        orchard_shielded_data: None,
        network_upgrade: NetworkUpgrade::Nu5,
    };

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction.clone()),
            known_utxos: Arc::new(known_utxos),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result,
        Err(TransactionError::ExpiredTransaction {
            expiry_height,
            block_height,
            transaction_hash: transaction.hash(),
        })
    );
}

/// Tests if a non-coinbase V5 transaction with an expiry height exceeding the maximum is rejected.
#[tokio::test]
async fn v5_transaction_with_exceeding_expiry_height() {
    let state = service_fn(|_| async { unreachable!("State service should not be called") });

    let height_max = block::Height::MAX;

    let (input, output, known_utxos) = mock_transparent_transfer(
        height_max.previous().expect("valid height"),
        true,
        0,
        Amount::try_from(1).expect("valid amount"),
    );

    // This expiry height exceeds the maximum defined by the specification.
    let expiry_height = block::Height(500_000_000);

    // Create a non-coinbase V5 tx.
    let transaction = Transaction::V5 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        expiry_height,
        sapling_shielded_data: None,
        orchard_shielded_data: None,
        network_upgrade: NetworkUpgrade::Nu6_1,
    };

    let transaction_hash = transaction.hash();

    let verification_result = Verifier::new_for_tests(&Network::Mainnet, state)
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction.clone()),
            known_utxos: Arc::new(known_utxos),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: height_max,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        verification_result,
        Err(TransactionError::MaximumExpiryHeight {
            expiry_height,
            is_coinbase: false,
            block_height: height_max,
            transaction_hash,
        })
    );
}

/// Test if V5 coinbase transaction is accepted.
#[tokio::test]
async fn v5_coinbase_transaction_is_accepted() {
    let network = Network::new_default_testnet();
    let network_upgrade = NetworkUpgrade::Nu5;

    let nu5_activation_height = network_upgrade
        .activation_height(&network)
        .expect("NU5 activation height is specified");

    let transaction_block_height =
        (nu5_activation_height + 10).expect("transaction block height is too large");

    // Create a fake transparent coinbase that should succeed
    let (input, output) = mock_coinbase_transparent_output(transaction_block_height);
    let known_utxos = HashMap::new();

    // Create a V5 coinbase transaction
    let transaction = Transaction::V5 {
        network_upgrade,
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::Height(block::Height(0)),
        expiry_height: transaction_block_height,
        sapling_shielded_data: None,
        orchard_shielded_data: None,
    };

    let transaction_hash = transaction.unmined_id();

    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&network, state_service);

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction),
            known_utxos: Arc::new(known_utxos),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: transaction_block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result.expect("unexpected error response").tx_id(),
        transaction_hash
    );
}

/// Test if V5 transaction with transparent funds is rejected if the source script prevents it.
///
/// This test simulates the case where the script verifier rejects the transaction because the
/// script prevents spending the source UTXO.
#[tokio::test]
async fn v5_transaction_with_transparent_transfer_is_rejected_by_the_script() {
    let network = Network::new_default_testnet();
    let network_upgrade = NetworkUpgrade::Nu5;

    let nu5_activation_height = network_upgrade
        .activation_height(&network)
        .expect("NU5 activation height is specified");

    let transaction_block_height =
        (nu5_activation_height + 10).expect("transaction block height is too large");

    let fake_source_fund_height =
        (transaction_block_height - 1).expect("fake source fund block height is too small");

    // Create a fake transparent transfer that should not succeed
    let (input, output, known_utxos) = mock_transparent_transfer(
        fake_source_fund_height,
        false,
        0,
        Amount::try_from(1).expect("invalid value"),
    );

    // Create a V5 transaction
    let transaction = Transaction::V5 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::Height(block::Height(0)),
        expiry_height: (transaction_block_height + 1).expect("expiry height is too large"),
        sapling_shielded_data: None,
        orchard_shielded_data: None,
        network_upgrade,
    };

    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called") });
    let verifier = Verifier::new_for_tests(&network, state_service);

    let result = verifier
        .oneshot(Request::Block {
            transaction_hash: transaction.hash(),
            transaction: Arc::new(transaction),
            known_utxos: Arc::new(known_utxos),
            known_outpoint_hashes: Arc::new(HashSet::new()),
            height: transaction_block_height,
            time: DateTime::<Utc>::MAX_UTC,
        })
        .await;

    assert_eq!(
        result,
        Err(TransactionError::InternalDowncastError(
            "downcast to known transaction error type failed, original error: ScriptInvalid"
                .to_string()
        ))
    );
}

/// Test if V5 transaction with an internal double spend of transparent funds is rejected.
#[tokio::test]
async fn v5_transaction_with_conflicting_transparent_spend_is_rejected() {
    for network in Network::iter() {
        let canopy_activation_height = NetworkUpgrade::Canopy
            .activation_height(&network)
            .expect("Canopy activation height is specified");

        let height = (canopy_activation_height + 10).expect("valid height");

        // Create a fake transparent transfer that should succeed
        let (input, output, known_utxos) = mock_transparent_transfer(
            height.previous().expect("valid height"),
            true,
            0,
            Amount::try_from(1).expect("valid amount"),
        );

        let transaction = Transaction::V5 {
            inputs: vec![input.clone(), input.clone()],
            outputs: vec![output],
            lock_time: LockTime::Height(block::Height(0)),
            expiry_height: height.next().expect("valid height"),
            sapling_shielded_data: None,
            orchard_shielded_data: None,
            network_upgrade: NetworkUpgrade::Canopy,
        };

        let state = service_fn(|_| async { unreachable!("State service should not be called") });

        let verification_result = Verifier::new_for_tests(&network, state)
            .oneshot(Request::Block {
                transaction_hash: transaction.hash(),
                transaction: Arc::new(transaction),
                known_utxos: Arc::new(known_utxos),
                known_outpoint_hashes: Arc::new(HashSet::new()),
                height,
                time: DateTime::<Utc>::MAX_UTC,
            })
            .await;

        assert_eq!(
            verification_result,
            Err(TransactionError::DuplicateTransparentSpend(
                input.outpoint().expect("Input should have an outpoint")
            ))
        );
    }
}

/// Test if signed V4 transaction with a dummy [`sprout::JoinSplit`] is accepted.
///
/// This test verifies if the transaction verifier correctly accepts a signed transaction.
#[test]
fn v4_with_signed_sprout_transfer_is_accepted() {
    let _init_guard = zebra_test::init();
    zebra_test::MULTI_THREADED_RUNTIME.block_on(async {
        let network = Network::Mainnet;

        let (height, transaction) = test_transactions(&network)
            .rev()
            .filter(|(_, transaction)| {
                !transaction.is_coinbase() && transaction.inputs().is_empty()
            })
            .find(|(_, transaction)| transaction.sprout_groth16_joinsplits().next().is_some())
            .expect("No transaction found with Groth16 JoinSplits");

        let expected_hash = transaction.unmined_id();

        // Initialize the verifier
        let state_service =
            service_fn(|_| async { unreachable!("State service should not be called") });
        let verifier = Verifier::new_for_tests(&network, state_service);

        // Test the transaction verifier
        let result = verifier
            .oneshot(Request::Block {
                transaction_hash: transaction.hash(),
                transaction,
                known_utxos: Arc::new(HashMap::new()),
                known_outpoint_hashes: Arc::new(HashSet::new()),
                height,
                time: DateTime::<Utc>::MAX_UTC,
            })
            .await;

        assert_eq!(
            result.expect("unexpected error response").tx_id(),
            expected_hash
        );
    })
}

/// Test if an V4 transaction with a modified [`sprout::JoinSplit`] is rejected.
///
/// This test verifies if the transaction verifier correctly rejects the transaction because of the
/// invalid JoinSplit.
#[test]
fn v4_with_modified_joinsplit_is_rejected() {
    let _init_guard = zebra_test::init();
    zebra_test::MULTI_THREADED_RUNTIME.block_on(async {
        v4_with_joinsplit_is_rejected_for_modification(
            JoinSplitModification::CorruptSignature,
            // TODO: Fix error downcast
            // Err(TransactionError::Ed25519(ed25519::Error::InvalidSignature))
            TransactionError::InternalDowncastError(
                "downcast to known transaction error type failed, original error: InvalidSignature"
                    .to_string(),
            ),
        )
        .await;

        v4_with_joinsplit_is_rejected_for_modification(
            JoinSplitModification::CorruptProof,
            TransactionError::Groth16("proof verification failed".to_string()),
        )
        .await;

        v4_with_joinsplit_is_rejected_for_modification(
            JoinSplitModification::ZeroProof,
            TransactionError::MalformedGroth16("invalid G1".to_string()),
        )
        .await;
    })
}

async fn v4_with_joinsplit_is_rejected_for_modification(
    modification: JoinSplitModification,
    expected_error: TransactionError,
) {
    let network = Network::Mainnet;

    let (height, mut transaction) = test_transactions(&network)
        .rev()
        .filter(|(_, tx)| {
            !tx.is_coinbase() && tx.inputs().is_empty() && !tx.has_sapling_shielded_data()
        })
        .find(|(_, tx)| tx.sprout_groth16_joinsplits().next().is_some())
        .expect("There should be a tx with Groth16 JoinSplits.");

    let expected_error = Err(expected_error);

    // Modify a JoinSplit in the transaction following the given modification type.
    let tx = Arc::get_mut(&mut transaction).expect("The tx should have only one active reference.");
    match tx {
        Transaction::V4 {
            joinsplit_data: Some(ref mut joinsplit_data),
            ..
        } => modify_joinsplit_data(joinsplit_data, modification),
        _ => unreachable!("Transaction should have some JoinSplit shielded data."),
    }

    // Initialize the verifier
    let state_service =
        service_fn(|_| async { unreachable!("State service should not be called.") });
    let verifier = Verifier::new_for_tests(&network, state_service);
    let verifier = Buffer::new(verifier, 10);

    // Test the transaction verifier.
    //
    // Note that modifying the JoinSplit data invalidates the tx signatures. The signatures are
    // checked concurrently with the ZK proofs, and when a signature check finishes before the proof
    // check, the verifier reports an invalid signature instead of invalid proof. This race
    // condition happens only occasionally, so we run the verifier in a loop with a small iteration
    // threshold until it returns the correct error.
    let mut i = 1;
    let result = loop {
        let result = verifier
            .clone()
            .oneshot(Request::Block {
                transaction_hash: transaction.hash(),
                transaction: transaction.clone(),
                known_utxos: Arc::new(HashMap::new()),
                known_outpoint_hashes: Arc::new(HashSet::new()),
                height,
                time: DateTime::<Utc>::MAX_UTC,
            })
            .await
            .map_err(|err| {
                *err.downcast()
                    .expect("error type should be TransactionError")
            });

        if result == expected_error || i >= 100 {
            break result;
        }

        i += 1;
    };

    assert_eq!(result, expected_error);
}

/// Test if a V4 transaction with Sapling spends is accepted by the verifier.
#[test]
fn v4_with_sapling_spends() {
    let _init_guard = zebra_test::init();
    zebra_test::MULTI_THREADED_RUNTIME.block_on(async {
        let network = Network::Mainnet;

        let (height, transaction) = test_transactions(&network)
            .rev()
            .filter(|(_, transaction)| {
                !transaction.is_coinbase() && transaction.inputs().is_empty()
            })
            .find(|(_, transaction)| transaction.sapling_spends_per_anchor().next().is_some())
            .expect("No transaction found with Sapling spends");

        let expected_hash = transaction.unmined_id();

        // Initialize the verifier
        let state_service =
            service_fn(|_| async { unreachable!("State service should not be called") });
        let verifier = Verifier::new_for_tests(&network, state_service);

        // Test the transaction verifier
        let result = timeout(
            test_timeout(),
            verifier.oneshot(Request::Block {
                transaction_hash: transaction.hash(),
                transaction,
                known_utxos: Arc::new(HashMap::new()),
                known_outpoint_hashes: Arc::new(HashSet::new()),
                height,
                time: DateTime::<Utc>::MAX_UTC,
            }),
        )
        .await
        .expect("timeout expired");

        assert_eq!(
            result.expect("unexpected error response").tx_id(),
            expected_hash
        );
    });
}

/// Test if a V4 transaction with a duplicate Sapling spend is rejected by the verifier.
#[test]
fn v4_with_duplicate_sapling_spends() {
    let _init_guard = zebra_test::init();
    zebra_test::MULTI_THREADED_RUNTIME.block_on(async {
        let network = Network::Mainnet;

        let (height, mut transaction) = test_transactions(&network)
            .rev()
            .filter(|(_, transaction)| {
                !transaction.is_coinbase() && transaction.inputs().is_empty()
            })
            .find(|(_, transaction)| transaction.sapling_spends_per_anchor().next().is_some())
            .expect("No transaction found with Sapling spends");

        // Duplicate one of the spends
        let duplicate_nullifier = duplicate_sapling_spend(
            Arc::get_mut(&mut transaction).expect("Transaction only has one active reference"),
        );

        // Initialize the verifier
        let state_service =
            service_fn(|_| async { unreachable!("State service should not be called") });
        let verifier = Verifier::new_for_tests(&network, state_service);

        // Test the transaction verifier
        let result = verifier
            .oneshot(Request::Block {
                transaction_hash: transaction.hash(),
                transaction,
                known_utxos: Arc::new(HashMap::new()),
                known_outpoint_hashes: Arc::new(HashSet::new()),
                height,
                time: DateTime::<Utc>::MAX_UTC,
            })
            .await;

        assert_eq!(
            result,
            Err(TransactionError::DuplicateSaplingNullifier(
                duplicate_nullifier
            ))
        );
    });
}

/// Test if a V4 transaction with Sapling outputs but no spends is accepted by the verifier.
#[test]
fn v4_with_sapling_outputs_and_no_spends() {
    let _init_guard = zebra_test::init();
    zebra_test::MULTI_THREADED_RUNTIME.block_on(async {
        let network = Network::Mainnet;

        let (height, transaction) = test_transactions(&network)
            .rev()
            .filter(|(_, transaction)| {
                !transaction.is_coinbase() && transaction.inputs().is_empty()
            })
            .find(|(_, transaction)| {
                transaction.sapling_spends_per_anchor().next().is_none()
                    && transaction.sapling_outputs().next().is_some()
            })
            .expect("No transaction found with Sapling outputs and no Sapling spends");

        let expected_hash = transaction.unmined_id();

        // Initialize the verifier
        let state_service =
            service_fn(|_| async { unreachable!("State service should not be called") });
        let verifier = Verifier::new_for_tests(&network, state_service);

        // Test the transaction verifier
        let result = verifier
            .oneshot(Request::Block {
                transaction_hash: transaction.hash(),
                transaction,
                known_utxos: Arc::new(HashMap::new()),
                known_outpoint_hashes: Arc::new(HashSet::new()),
                height,
                time: DateTime::<Utc>::MAX_UTC,
            })
            .await;

        assert_eq!(
            result.expect("unexpected error response").tx_id(),
            expected_hash
        );
    })
}

/// Test if a V5 transaction with Sapling spends is accepted by the verifier.
#[tokio::test]
async fn v5_with_sapling_spends() {
    let _init_guard = zebra_test::init();

    for net in Network::iter() {
        let nu5_activation = NetworkUpgrade::Nu5.activation_height(&net);

        let tx = v5_transactions(net.block_iter())
            .filter(|tx| {
                !tx.is_coinbase() && tx.inputs().is_empty() && tx.expiry_height() >= nu5_activation
            })
            .find(|tx| tx.sapling_spends_per_anchor().next().is_some())
            .expect("V5 tx with Sapling spends");

        let expected_hash = tx.unmined_id();
        let height = tx.expiry_height().expect("expiry height");

        let verifier = Verifier::new_for_tests(
            &net,
            service_fn(|_| async { unreachable!("State service should not be called") }),
        );

        assert_eq!(
            timeout(
                test_timeout(),
                verifier.oneshot(Request::Block {
                    transaction_hash: tx.hash(),
                    transaction: Arc::new(tx),
                    known_utxos: Arc::new(HashMap::new()),
                    known_outpoint_hashes: Arc::new(HashSet::new()),
                    height,
                    time: DateTime::<Utc>::MAX_UTC,
                })
            )
            .await
            .expect("timeout expired")
            .expect("unexpected error response")
            .tx_id(),
            expected_hash
        );
    }
}

/// Test if a V5 transaction with a duplicate Sapling spend is rejected by the verifier.
#[tokio::test]
async fn v5_with_duplicate_sapling_spends() {
    let _init_guard = zebra_test::init();

    for net in Network::iter() {
        let mut tx = v5_transactions(net.block_iter())
            .filter(|tx| !tx.is_coinbase() && tx.inputs().is_empty())
            .find(|tx| tx.sapling_spends_per_anchor().next().is_some())
            .expect("V5 tx with Sapling spends");

        let height = tx.expiry_height().expect("expiry height");

        // Duplicate one of the spends
        let duplicate_nullifier = duplicate_sapling_spend(&mut tx);

        let verifier = Verifier::new_for_tests(
            &net,
            service_fn(|_| async { unreachable!("State service should not be called") }),
        );

        assert_eq!(
            verifier
                .oneshot(Request::Block {
                    transaction_hash: tx.hash(),
                    transaction: Arc::new(tx),
                    known_utxos: Arc::new(HashMap::new()),
                    known_outpoint_hashes: Arc::new(HashSet::new()),
                    height,
                    time: DateTime::<Utc>::MAX_UTC,
                })
                .await,
            Err(TransactionError::DuplicateSaplingNullifier(
                duplicate_nullifier
            ))
        );
    }
}

/// Test if a V5 transaction with a duplicate Orchard action is rejected by the verifier.
#[tokio::test]
async fn v5_with_duplicate_orchard_action() {
    let _init_guard = zebra_test::init();

    for net in Network::iter() {
        let mut tx = v5_transactions(net.block_iter())
            .rev()
            .find(|transaction| {
                transaction.inputs().is_empty()
                    && transaction.outputs().is_empty()
                    && transaction.sapling_spends_per_anchor().next().is_none()
                    && transaction.sapling_outputs().next().is_none()
                    && transaction.joinsplit_count() == 0
            })
            .expect("V5 tx with only Orchard actions");

        let height = tx.expiry_height().expect("expiry height");

        let orchard_shielded_data = tx
            .orchard_shielded_data_mut()
            .expect("tx without transparent, Sprout, or Sapling outputs must have Orchard actions");

        // Enable spends
        orchard_shielded_data.flags = Flags::ENABLE_SPENDS | Flags::ENABLE_OUTPUTS;

        let duplicate_action = orchard_shielded_data.actions.first().clone();
        let duplicate_nullifier = duplicate_action.action.nullifier;

        // Duplicate the first action
        let mut actions_vec = orchard_shielded_data.actions.as_slice().to_vec();
        actions_vec.push(duplicate_action.clone());
        orchard_shielded_data.actions = AtLeastOne::from_vec(actions_vec)
            .expect("pushing one element never breaks at least one constraints");

        let verifier = Verifier::new_for_tests(
            &net,
            service_fn(|_| async { unreachable!("State service should not be called") }),
        );

        assert_eq!(
            verifier
                .oneshot(Request::Block {
                    transaction_hash: tx.hash(),
                    transaction: Arc::new(tx),
                    known_utxos: Arc::new(HashMap::new()),
                    known_outpoint_hashes: Arc::new(HashSet::new()),
                    height,
                    time: DateTime::<Utc>::MAX_UTC,
                })
                .await,
            Err(TransactionError::DuplicateOrchardNullifier(
                duplicate_nullifier
            ))
        );
    }
}

/// Checks that the tx verifier handles consensus branch ids in V5 txs correctly.
#[tokio::test]
async fn v5_consensus_branch_ids() {
    let mut state = MockService::build().for_unit_tests();

    let (input, output, known_utxos) = mock_transparent_transfer(
        Height(1),
        true,
        0,
        Amount::try_from(10001).expect("valid amount"),
    );

    let known_utxos = Arc::new(known_utxos);

    // NU5 is the first network upgrade that supports V5 txs.
    let mut network_upgrade = NetworkUpgrade::Nu5;

    let mut tx = Transaction::V5 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        expiry_height: Height::MAX_EXPIRY_HEIGHT,
        sapling_shielded_data: None,
        orchard_shielded_data: None,
        network_upgrade,
    };

    let outpoint = match tx.inputs()[0] {
        transparent::Input::PrevOut { outpoint, .. } => outpoint,
        transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
    };

    for network in Network::iter() {
        let verifier = Buffer::new(Verifier::new_for_tests(&network, state.clone()), 10);

        while let Some(next_nu) = network_upgrade.next_upgrade() {
            // Check an outdated network upgrade.
            let Some(height) = next_nu.activation_height(&network) else {
                tracing::warn!(?next_nu, "missing activation height",);
                // Shift the network upgrade for the next loop iteration.
                network_upgrade = next_nu;
                continue;
            };

            let block_req = verifier
                .clone()
                .oneshot(Request::Block {
                    transaction_hash: tx.hash(),
                    transaction: Arc::new(tx.clone()),
                    known_utxos: known_utxos.clone(),
                    known_outpoint_hashes: Arc::new(HashSet::new()),
                    // The consensus branch ID of the tx is outdated for this height.
                    height,
                    time: DateTime::<Utc>::MAX_UTC,
                })
                .map_err(|err| *err.downcast().expect("`TransactionError` type"));

            let mempool_req = verifier
                .clone()
                .oneshot(Request::Mempool {
                    transaction: tx.clone().into(),
                    // The consensus branch ID of the tx is outdated for this height.
                    height,
                })
                .map_err(|err| *err.downcast().expect("`TransactionError` type"));

            let (block_rsp, mempool_rsp) = futures::join!(block_req, mempool_req);

            assert_eq!(block_rsp, Err(TransactionError::WrongConsensusBranchId));
            assert_eq!(mempool_rsp, Err(TransactionError::WrongConsensusBranchId));

            // Check the currently supported network upgrade.
            let height = network_upgrade.activation_height(&network).expect("height");

            let block_req = verifier
                .clone()
                .oneshot(Request::Block {
                    transaction_hash: tx.hash(),
                    transaction: Arc::new(tx.clone()),
                    known_utxos: known_utxos.clone(),
                    known_outpoint_hashes: Arc::new(HashSet::new()),
                    // The consensus branch ID of the tx is supported by this height.
                    height,
                    time: DateTime::<Utc>::MAX_UTC,
                })
                .map_ok(|rsp| rsp.tx_id())
                .map_err(|e| format!("{e}"));

            let mempool_req = verifier
                .clone()
                .oneshot(Request::Mempool {
                    transaction: tx.clone().into(),
                    // The consensus branch ID of the tx is supported by this height.
                    height,
                })
                .map_ok(|rsp| rsp.tx_id())
                .map_err(|e| format!("{e}"));

            let state_req = async {
                state
                    .expect_request(zebra_state::Request::UnspentBestChainUtxo(outpoint))
                    .map(|r| {
                        r.respond(zebra_state::Response::UnspentBestChainUtxo(
                            known_utxos.get(&outpoint).map(|utxo| utxo.utxo.clone()),
                        ))
                    })
                    .await;

                state
                    .expect_request_that(|req| {
                        matches!(
                            req,
                            zebra_state::Request::CheckBestChainTipNullifiersAndAnchors(_)
                        )
                    })
                    .map(|r| {
                        r.respond(zebra_state::Response::ValidBestChainTipNullifiersAndAnchors)
                    })
                    .await;
            };

            let (block_rsp, mempool_rsp, _) = futures::join!(block_req, mempool_req, state_req);
            let txid = tx.unmined_id();

            assert_eq!(block_rsp, Ok(txid));
            assert_eq!(mempool_rsp, Ok(txid));

            // Check a network upgrade that Zebra doesn't support yet.
            tx.update_network_upgrade(next_nu)
                .expect("V5 txs support updating NUs");

            let height = network_upgrade.activation_height(&network).expect("height");

            let block_req = verifier
                .clone()
                .oneshot(Request::Block {
                    transaction_hash: tx.hash(),
                    transaction: Arc::new(tx.clone()),
                    known_utxos: known_utxos.clone(),
                    known_outpoint_hashes: Arc::new(HashSet::new()),
                    // The consensus branch ID of the tx is not supported by this height.
                    height,
                    time: DateTime::<Utc>::MAX_UTC,
                })
                .map_err(|err| *err.downcast().expect("`TransactionError` type"));

            let mempool_req = verifier
                .clone()
                .oneshot(Request::Mempool {
                    transaction: tx.clone().into(),
                    // The consensus branch ID of the tx is not supported by this height.
                    height,
                })
                .map_err(|err| *err.downcast().expect("`TransactionError` type"));

            let (block_rsp, mempool_rsp) = futures::join!(block_req, mempool_req);

            assert_eq!(block_rsp, Err(TransactionError::WrongConsensusBranchId));
            assert_eq!(mempool_rsp, Err(TransactionError::WrongConsensusBranchId));

            // Shift the network upgrade for the next loop iteration.
            network_upgrade = next_nu;
        }
    }
}

// Utility functions

/// Create a mock transparent transfer to be included in a transaction.
///
/// First, this creates a fake unspent transaction output from a fake transaction included in the
/// specified `previous_utxo_height` block height. This fake [`Utxo`] also contains a simple script
/// that can either accept or reject any spend attempt, depending on if `script_should_succeed` is
/// `true` or `false`. Since the `tx_index_in_block` is irrelevant for blocks that have already
/// been verified, it is set to `1`.
///
/// Then, a [`transparent::Input::PrevOut`] is created that attempts to spend the previously created fake
/// UTXO to a new [`transparent::Output`].
///
/// Finally, the initial fake UTXO is placed in a `known_utxos` [`HashMap`] so that it can be
/// retrieved during verification.
///
/// The function then returns the generated transparent input and output, as well as the
/// `known_utxos` map.
///
/// Note: `known_utxos` is only intended to be used for UTXOs within the same block,
/// so future verification changes might break this mocking function.
fn mock_transparent_transfer(
    previous_utxo_height: block::Height,
    script_should_succeed: bool,
    outpoint_index: u32,
    previous_output_value: Amount<NonNegative>,
) -> (
    transparent::Input,
    transparent::Output,
    HashMap<transparent::OutPoint, transparent::OrderedUtxo>,
) {
    // A script with a single opcode that accepts the transaction (pushes true on the stack)
    let accepting_script = transparent::Script::new(&[1, 1]);
    // A script with a single opcode that rejects the transaction (OP_FALSE)
    let rejecting_script = transparent::Script::new(&[0]);

    // Mock an unspent transaction output
    let previous_outpoint = transparent::OutPoint {
        hash: Hash([1u8; 32]),
        index: outpoint_index,
    };

    let lock_script = if script_should_succeed {
        accepting_script.clone()
    } else {
        rejecting_script.clone()
    };

    let previous_output = transparent::Output {
        value: previous_output_value,
        lock_script,
    };

    let previous_utxo = transparent::OrderedUtxo::new(previous_output, previous_utxo_height, 1);

    // Use the `previous_outpoint` as input
    let input = transparent::Input::PrevOut {
        outpoint: previous_outpoint,
        unlock_script: accepting_script,
        sequence: 0,
    };

    // The output resulting from the transfer
    // Using the rejecting script pretends the amount is burned because it can't be spent again
    let output = transparent::Output {
        value: Amount::try_from(1).expect("1 is an invalid amount"),
        lock_script: rejecting_script,
    };

    // Cache the source of the fund so that it can be used during verification
    let mut known_utxos = HashMap::new();
    known_utxos.insert(previous_outpoint, previous_utxo);

    (input, output, known_utxos)
}

/// Create a mock coinbase input with a transparent output.
///
/// Create a [`transparent::Input::Coinbase`] at `coinbase_height`.
/// Then create UTXO with a [`transparent::Output`] spending some coinbase funds.
///
/// Returns the generated coinbase input and transparent output.
fn mock_coinbase_transparent_output(
    coinbase_height: block::Height,
) -> (transparent::Input, transparent::Output) {
    // A script with a single opcode that rejects the transaction (OP_FALSE)
    let rejecting_script = transparent::Script::new(&[0]);

    let input = transparent::Input::Coinbase {
        height: coinbase_height,
        data: CoinbaseData::new(Vec::new()),
        sequence: u32::MAX,
    };

    // The output resulting from the transfer
    // Using the rejecting script pretends the amount is burned because it can't be spent again
    let output = transparent::Output {
        value: Amount::try_from(1).expect("1 is an invalid amount"),
        lock_script: rejecting_script,
    };

    (input, output)
}

/// Create a mock [`sprout::JoinSplit`] and include it in a [`transaction::JoinSplitData`].
///
/// This creates a dummy join split. By itself it is invalid, but it is useful for including in a
/// transaction to check the signatures.
///
/// The [`transaction::JoinSplitData`] with the dummy [`sprout::JoinSplit`] is returned together
/// with the [`ed25519::SigningKey`] that can be used to create a signature to later add to the
/// returned join split data.
fn mock_sprout_join_split_data() -> (JoinSplitData<Groth16Proof>, ed25519::SigningKey) {
    // Prepare dummy inputs for the join split
    let zero_amount = 0_i32
        .try_into()
        .expect("Invalid JoinSplit transparent input");
    let anchor = sprout::tree::Root::default();
    let first_nullifier = sprout::note::Nullifier([0u8; 32].into());
    let second_nullifier = sprout::note::Nullifier([1u8; 32].into());
    let commitment = sprout::commitment::NoteCommitment::from([0u8; 32]);
    let ephemeral_key =
        x25519::PublicKey::from(&x25519::EphemeralSecret::random_from_rng(rand::thread_rng()));
    let random_seed = sprout::RandomSeed::from([0u8; 32]);
    let mac = sprout::note::Mac::zcash_deserialize(&[0u8; 32][..])
        .expect("Failure to deserialize dummy MAC");
    let zkproof = Groth16Proof([0u8; 192]);
    let encrypted_note = sprout::note::EncryptedNote([0u8; 601]);

    // Create an dummy join split
    let joinsplit = sprout::JoinSplit {
        vpub_old: zero_amount,
        vpub_new: zero_amount,
        anchor,
        nullifiers: [first_nullifier, second_nullifier],
        commitments: [commitment; 2],
        ephemeral_key,
        random_seed,
        vmacs: [mac.clone(), mac],
        zkproof,
        enc_ciphertexts: [encrypted_note; 2],
    };

    // Create a usable signing key
    let signing_key = ed25519::SigningKey::new(rand::thread_rng());
    let verification_key = ed25519::VerificationKey::from(&signing_key);

    // Populate join split data with the dummy join split.
    let joinsplit_data = JoinSplitData {
        first: joinsplit,
        rest: vec![],
        pub_key: verification_key.into(),
        sig: [0u8; 64].into(),
    };

    (joinsplit_data, signing_key)
}

/// A type of JoinSplit modification to test.
#[derive(Clone, Copy)]
enum JoinSplitModification {
    // Corrupt a signature, making it invalid.
    CorruptSignature,
    // Corrupt a proof, making it invalid, but still well-formed.
    CorruptProof,
    // Make a proof all-zeroes, making it malformed.
    ZeroProof,
}

/// Modify a [`JoinSplitData`] following the given modification type.
fn modify_joinsplit_data(
    joinsplit_data: &mut JoinSplitData<Groth16Proof>,
    modification: JoinSplitModification,
) {
    match modification {
        JoinSplitModification::CorruptSignature => {
            let mut sig_bytes: [u8; 64] = joinsplit_data.sig.into();
            // Flip a bit from an arbitrary byte of the signature.
            sig_bytes[10] ^= 0x01;
            joinsplit_data.sig = sig_bytes.into();
        }
        JoinSplitModification::CorruptProof => {
            let joinsplit = joinsplit_data
                .joinsplits_mut()
                .next()
                .expect("must have a JoinSplit");
            {
                // A proof is composed of three field elements, the first and last having 48 bytes.
                // (The middle one has 96 bytes.) To corrupt the proof without making it malformed,
                // simply swap those first and last elements.
                let (first, rest) = joinsplit.zkproof.0.split_at_mut(48);
                first.swap_with_slice(&mut rest[96..144]);
            }
        }
        JoinSplitModification::ZeroProof => {
            let joinsplit = joinsplit_data
                .joinsplits_mut()
                .next()
                .expect("must have a JoinSplit");
            joinsplit.zkproof.0 = [0; 192];
        }
    }
}

/// Duplicate a Sapling spend inside a `transaction`.
///
/// Returns the nullifier of the duplicate spend.
///
/// # Panics
///
/// Will panic if the `transaction` does not have Sapling spends.
fn duplicate_sapling_spend(transaction: &mut Transaction) -> sapling::Nullifier {
    match transaction {
        Transaction::V4 {
            sapling_shielded_data: Some(ref mut shielded_data),
            ..
        } => duplicate_sapling_spend_in_shielded_data(shielded_data),
        Transaction::V5 {
            sapling_shielded_data: Some(ref mut shielded_data),
            ..
        } => duplicate_sapling_spend_in_shielded_data(shielded_data),
        _ => unreachable!("Transaction has no Sapling shielded data"),
    }
}

/// Duplicates the first spend of the `shielded_data`.
///
/// Returns the nullifier of the duplicate spend.
///
/// # Panics
///
/// Will panic if `shielded_data` has no spends.
fn duplicate_sapling_spend_in_shielded_data<A: sapling::AnchorVariant + Clone>(
    shielded_data: &mut sapling::ShieldedData<A>,
) -> sapling::Nullifier {
    match shielded_data.transfers {
        sapling::TransferData::SpendsAndMaybeOutputs { ref mut spends, .. } => {
            let duplicate_spend = spends.first().clone();
            let duplicate_nullifier = duplicate_spend.nullifier;

            let mut spends_vec = spends.as_slice().to_vec();
            spends_vec.push(duplicate_spend);
            *spends = AtLeastOne::from_vec(spends_vec)
                .expect("pushing one element never breaks at least one constraints");

            duplicate_nullifier
        }
        sapling::TransferData::JustOutputs { .. } => {
            unreachable!("Sapling shielded data has no spends")
        }
    }
}

#[test]
fn add_to_sprout_pool_after_nu() {
    let _init_guard = zebra_test::init();

    // get a block that we know it haves a transaction with `vpub_old` field greater than 0.
    let block: Arc<_> = zebra_chain::block::Block::zcash_deserialize(
        &zebra_test::vectors::BLOCK_MAINNET_419199_BYTES[..],
    )
    .unwrap()
    .into();

    // create a block height at canopy activation.
    let network = Network::Mainnet;
    let block_height = NetworkUpgrade::Canopy.activation_height(&network).unwrap();

    // create a zero amount.
    let zero = Amount::<NonNegative>::try_from(0).expect("an amount of 0 is always valid");

    // the coinbase transaction should pass the check.
    assert_eq!(
        check::disabled_add_to_sprout_pool(&block.transactions[0], block_height, &network),
        Ok(())
    );

    // the 2nd transaction has no joinsplits, should pass the check.
    assert_eq!(block.transactions[1].joinsplit_count(), 0);
    assert_eq!(
        check::disabled_add_to_sprout_pool(&block.transactions[1], block_height, &network),
        Ok(())
    );

    // the 5th transaction has joinsplits and the `vpub_old` cumulative is greater than 0,
    // should fail the check.
    assert!(block.transactions[4].joinsplit_count() > 0);
    let vpub_old: Amount<NonNegative> = block.transactions[4]
        .output_values_to_sprout()
        .fold(zero, |acc, &x| (acc + x).unwrap());
    assert!(vpub_old > zero);

    assert_eq!(
        check::disabled_add_to_sprout_pool(&block.transactions[3], block_height, &network),
        Err(TransactionError::DisabledAddToSproutPool)
    );

    // the 8th transaction has joinsplits and the `vpub_old` cumulative is 0,
    // should pass the check.
    assert!(block.transactions[7].joinsplit_count() > 0);
    let vpub_old: Amount<NonNegative> = block.transactions[7]
        .output_values_to_sprout()
        .fold(zero, |acc, &x| (acc + x).unwrap());
    assert_eq!(vpub_old, zero);

    assert_eq!(
        check::disabled_add_to_sprout_pool(&block.transactions[7], block_height, &network),
        Ok(())
    );
}

/// Checks that Heartwood onward, all Sapling and Orchard outputs in coinbase txs decrypt to a note
/// plaintext, i.e. the procedure in § 4.20.3 ‘Decryption using a Full Viewing Key (Sapling and
/// Orchard )’ does not return ⊥, using a sequence of 32 zero bytes as the outgoing viewing key. We
/// will refer to such a sequence as the _zero key_.
#[test]
fn coinbase_outputs_are_decryptable() -> Result<(), Report> {
    let _init_guard = zebra_test::init();

    for net in Network::iter() {
        let mut tested_post_heartwood_shielded_coinbase_tx = false;
        let mut tested_pre_heartwood_shielded_coinbase_tx = false;

        let mut tested_post_heartwood_unshielded_coinbase_tx = false;
        let mut tested_pre_heartwood_unshielded_coinbase_tx = false;

        let mut tested_post_heartwood_shielded_non_coinbase_tx = false;
        let mut tested_pre_heartwood_shielded_non_coinbase_tx = false;

        let mut tested_post_heartwood_unshielded_non_coinbase_tx = false;
        let mut tested_pre_heartwood_unshielded_non_coinbase_tx = false;

        for (height, block) in net.block_iter() {
            let block = block.zcash_deserialize_into::<Block>().expect("block");
            let height = Height(*height);
            let is_heartwood = height >= NetworkUpgrade::Heartwood.activation_height(&net).unwrap();
            let coinbase = block.transactions.first().expect("coinbase transaction");

            if coinbase.has_shielded_outputs() && is_heartwood {
                tested_post_heartwood_shielded_coinbase_tx = true;
                check::coinbase_outputs_are_decryptable(coinbase, &net, height).expect(
                    "post-Heartwood shielded coinbase outputs must be decryptable with the zero key",
                );
            }

            if coinbase.has_shielded_outputs() && !is_heartwood {
                tested_pre_heartwood_shielded_coinbase_tx = true;
                check::coinbase_outputs_are_decryptable(coinbase, &net, height)
                    .expect("the consensus rule does not apply to pre-Heartwood txs");
            }

            if !coinbase.has_shielded_outputs() && is_heartwood {
                tested_post_heartwood_unshielded_coinbase_tx = true;
                check::coinbase_outputs_are_decryptable(coinbase, &net, height)
                    .expect("the consensus rule does not apply to txs with no shielded outputs");
            }

            if !coinbase.has_shielded_outputs() && !is_heartwood {
                tested_pre_heartwood_unshielded_coinbase_tx = true;
                check::coinbase_outputs_are_decryptable(coinbase, &net, height)
                    .expect("the consensus rule does not apply to pre-Heartwood txs");
            }

            // For non-coinbase txs, check if existing outputs are NOT decryptable with an all-zero
            // key, if applicable.
            for non_coinbase in block.transactions.iter().skip(1) {
                if non_coinbase.has_shielded_outputs() && is_heartwood {
                    tested_post_heartwood_shielded_non_coinbase_tx = true;
                    assert_eq!(
                        check::coinbase_outputs_are_decryptable(non_coinbase, &net, height),
                        Err(TransactionError::NotCoinbase)
                    )
                }

                if non_coinbase.has_shielded_outputs() && !is_heartwood {
                    tested_pre_heartwood_shielded_non_coinbase_tx = true;
                    check::coinbase_outputs_are_decryptable(non_coinbase, &net, height)
                        .expect("the consensus rule does not apply to pre-Heartwood txs");
                }

                if !non_coinbase.has_shielded_outputs() && is_heartwood {
                    tested_post_heartwood_unshielded_non_coinbase_tx = true;
                    check::coinbase_outputs_are_decryptable(non_coinbase, &net, height).expect(
                        "the consensus rule does not apply to txs with no shielded outputs",
                    );
                }

                if !non_coinbase.has_shielded_outputs() && !is_heartwood {
                    tested_pre_heartwood_unshielded_non_coinbase_tx = true;
                    check::coinbase_outputs_are_decryptable(non_coinbase, &net, height)
                        .expect("the consensus rule does not apply to pre-Heartwood txs");
                }
            }
        }

        assert!(tested_post_heartwood_shielded_coinbase_tx);
        // We have no pre-Heartwood shielded coinbase txs.
        assert!(!tested_pre_heartwood_shielded_coinbase_tx);
        assert!(tested_post_heartwood_unshielded_coinbase_tx);
        assert!(tested_pre_heartwood_unshielded_coinbase_tx);
        assert!(tested_post_heartwood_shielded_non_coinbase_tx);
        assert!(tested_pre_heartwood_shielded_non_coinbase_tx);
        assert!(tested_post_heartwood_unshielded_non_coinbase_tx);
        assert!(tested_pre_heartwood_unshielded_non_coinbase_tx);
    }

    Ok(())
}

/// Given an Orchard action as a base, fill fields related to note encryption
/// from the given test vector and returned the modified action.
fn fill_action_with_note_encryption_test_vector(
    action: &Action,
    v: &zebra_test::vectors::TestVector,
) -> Action {
    let mut action = action.clone();
    action.cv = v.cv_net.try_into().expect("test vector must be valid");
    action.cm_x = pallas::Base::from_repr(v.cmx).unwrap();
    action.nullifier = v.rho.try_into().expect("test vector must be valid");
    action.ephemeral_key = v
        .ephemeral_key
        .try_into()
        .expect("test vector must be valid");
    action.out_ciphertext = v.c_out.into();
    action.enc_ciphertext = v.c_enc.into();
    action
}

/// Test if shielded coinbase outputs are decryptable with an all-zero outgoing viewing key.
#[test]
fn coinbase_outputs_are_decryptable_for_fake_v5_blocks() {
    for v in zebra_test::vectors::ORCHARD_NOTE_ENCRYPTION_ZERO_VECTOR.iter() {
        for net in Network::iter() {
            let mut transaction = v5_transactions(net.block_iter())
                .find(|tx| tx.is_coinbase())
                .expect("coinbase V5 tx");

            let shielded_data = insert_fake_orchard_shielded_data(&mut transaction);
            shielded_data.flags = Flags::ENABLE_OUTPUTS;

            let action = fill_action_with_note_encryption_test_vector(
                &shielded_data.actions.first().action,
                v,
            );
            let sig = shielded_data.actions.first().spend_auth_sig;
            shielded_data.actions = vec![AuthorizedAction::from_parts(action, sig)]
                .try_into()
                .unwrap();

            assert_eq!(
                check::coinbase_outputs_are_decryptable(
                    &transaction,
                    &net,
                    NetworkUpgrade::Nu5.activation_height(&net).unwrap(),
                ),
                Ok(())
            );
        }
    }
}

/// Test if random shielded outputs are NOT decryptable with an all-zero outgoing viewing key.
#[test]
fn shielded_outputs_are_not_decryptable_for_fake_v5_blocks() {
    for v in zebra_test::vectors::ORCHARD_NOTE_ENCRYPTION_VECTOR.iter() {
        for net in Network::iter() {
            let mut tx = v5_transactions(net.block_iter())
                .find(|tx| tx.is_coinbase())
                .expect("V5 coinbase tx");

            let shielded_data = insert_fake_orchard_shielded_data(&mut tx);
            shielded_data.flags = Flags::ENABLE_OUTPUTS;

            let action = fill_action_with_note_encryption_test_vector(
                &shielded_data.actions.first().action,
                v,
            );
            let sig = shielded_data.actions.first().spend_auth_sig;
            shielded_data.actions = vec![AuthorizedAction::from_parts(action, sig)]
                .try_into()
                .unwrap();

            assert_eq!(
                check::coinbase_outputs_are_decryptable(
                    &tx,
                    &net,
                    NetworkUpgrade::Nu5.activation_height(&net).unwrap(),
                ),
                Err(TransactionError::CoinbaseOutputsNotDecryptable)
            );
        }
    }
}

#[tokio::test]
async fn mempool_zip317_error() {
    let mut state: MockService<_, _, _, _> = MockService::build().for_prop_tests();
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state.clone());

    let height = NetworkUpgrade::Nu5
        .activation_height(&Network::Mainnet)
        .expect("Nu5 activation height is specified");
    let fund_height = (height - 1).expect("fake source fund block height is too small");

    // Will produce a small enough miner fee to fail the check.
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(10).expect("valid amount"),
    );

    // Create a non-coinbase V5 tx.
    let tx = Transaction::V5 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        network_upgrade: NetworkUpgrade::Nu5,
        expiry_height: height,
        sapling_shielded_data: None,
        orchard_shielded_data: None,
    };

    let input_outpoint = match tx.inputs()[0] {
        transparent::Input::PrevOut { outpoint, .. } => outpoint,
        transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
    };

    tokio::spawn(async move {
        state
            .expect_request(zebra_state::Request::UnspentBestChainUtxo(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::UnspentBestChainUtxo(
                known_utxos
                    .get(&input_outpoint)
                    .map(|utxo| utxo.utxo.clone()),
            ));

        state
            .expect_request_that(|req| {
                matches!(
                    req,
                    zebra_state::Request::CheckBestChainTipNullifiersAndAnchors(_)
                )
            })
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::ValidBestChainTipNullifiersAndAnchors);
    });

    let verifier_response = verifier
        .oneshot(Request::Mempool {
            transaction: tx.into(),
            height,
        })
        .await;

    // Mempool refuses to add this transaction into storage.
    assert!(verifier_response.is_err());
    assert_eq!(
        verifier_response.err(),
        Some(TransactionError::Zip317(zip317::Error::UnpaidActions))
    );
}

#[tokio::test]
async fn mempool_zip317_ok() {
    let mut state: MockService<_, _, _, _> = MockService::build().for_prop_tests();
    let verifier = Verifier::new_for_tests(&Network::Mainnet, state.clone());

    let height = NetworkUpgrade::Nu5
        .activation_height(&Network::Mainnet)
        .expect("Nu5 activation height is specified");
    let fund_height = (height - 1).expect("fake source fund block height is too small");

    // Will produce a big enough miner fee to pass the check.
    let (input, output, known_utxos) = mock_transparent_transfer(
        fund_height,
        true,
        0,
        Amount::try_from(10_001).expect("valid amount"),
    );

    // Create a non-coinbase V5 tx.
    let tx = Transaction::V5 {
        inputs: vec![input],
        outputs: vec![output],
        lock_time: LockTime::unlocked(),
        network_upgrade: NetworkUpgrade::Nu5,
        expiry_height: height,
        sapling_shielded_data: None,
        orchard_shielded_data: None,
    };

    let input_outpoint = match tx.inputs()[0] {
        transparent::Input::PrevOut { outpoint, .. } => outpoint,
        transparent::Input::Coinbase { .. } => panic!("requires a non-coinbase transaction"),
    };

    tokio::spawn(async move {
        state
            .expect_request(zebra_state::Request::UnspentBestChainUtxo(input_outpoint))
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::UnspentBestChainUtxo(
                known_utxos
                    .get(&input_outpoint)
                    .map(|utxo| utxo.utxo.clone()),
            ));

        state
            .expect_request_that(|req| {
                matches!(
                    req,
                    zebra_state::Request::CheckBestChainTipNullifiersAndAnchors(_)
                )
            })
            .await
            .expect("verifier should call mock state service with correct request")
            .respond(zebra_state::Response::ValidBestChainTipNullifiersAndAnchors);
    });

    let verifier_response = verifier
        .oneshot(Request::Mempool {
            transaction: tx.into(),
            height,
        })
        .await;

    assert!(
        verifier_response.is_ok(),
        "expected successful verification, got: {verifier_response:?}"
    );
}