Actual no_std support
[rust-lightning] / lightning / src / util / test_utils.rs
index 6c3552d5df0853f1b8b2e79592573373c25f7c99..a9a10451b2c1dd0825a2f985e13075c45b759961 100644 (file)
@@ -8,6 +8,7 @@
 // licenses.
 
 use chain;
+use chain::WatchedOutput;
 use chain::chaininterface;
 use chain::chaininterface::ConfirmationTarget;
 use chain::chainmonitor;
@@ -18,31 +19,35 @@ use chain::keysinterface;
 use ln::features::{ChannelFeatures, InitFeatures};
 use ln::msgs;
 use ln::msgs::OptionalField;
-use util::enforcing_trait_impls::EnforcingChannelKeys;
+use util::enforcing_trait_impls::{EnforcingSigner, INITIAL_REVOKED_COMMITMENT_NUMBER};
 use util::events;
 use util::logger::{Logger, Level, Record};
-use util::ser::{Readable, Writer, Writeable};
+use util::ser::{Readable, ReadableArgs, Writer, Writeable};
 
 use bitcoin::blockdata::constants::genesis_block;
 use bitcoin::blockdata::transaction::{Transaction, TxOut};
 use bitcoin::blockdata::script::{Builder, Script};
 use bitcoin::blockdata::opcodes;
+use bitcoin::blockdata::block::BlockHeader;
 use bitcoin::network::constants::Network;
 use bitcoin::hash_types::{BlockHash, Txid};
 
 use bitcoin::secp256k1::{SecretKey, PublicKey, Secp256k1, Signature};
+use bitcoin::secp256k1::recovery::RecoverableSignature;
 
 use regex;
 
-use std::time::Duration;
-use std::sync::Mutex;
-use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
-use std::{cmp, mem};
-use std::collections::{HashMap, HashSet};
+use io;
+use prelude::*;
+use core::time::Duration;
+use sync::{Mutex, Arc};
+use core::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
+use core::{cmp, mem};
+use chain::keysinterface::InMemorySigner;
 
 pub struct TestVecWriter(pub Vec<u8>);
 impl Writer for TestVecWriter {
-       fn write_all(&mut self, buf: &[u8]) -> Result<(), ::std::io::Error> {
+       fn write_all(&mut self, buf: &[u8]) -> Result<(), io::Error> {
                self.0.extend_from_slice(buf);
                Ok(())
        }
@@ -52,44 +57,65 @@ impl Writer for TestVecWriter {
 }
 
 pub struct TestFeeEstimator {
-       pub sat_per_kw: u32,
+       pub sat_per_kw: Mutex<u32>,
 }
 impl chaininterface::FeeEstimator for TestFeeEstimator {
        fn get_est_sat_per_1000_weight(&self, _confirmation_target: ConfirmationTarget) -> u32 {
-               self.sat_per_kw
+               *self.sat_per_kw.lock().unwrap()
        }
 }
 
+pub struct OnlyReadsKeysInterface {}
+impl keysinterface::KeysInterface for OnlyReadsKeysInterface {
+       type Signer = EnforcingSigner;
+
+       fn get_node_secret(&self) -> SecretKey { unreachable!(); }
+       fn get_destination_script(&self) -> Script { unreachable!(); }
+       fn get_shutdown_pubkey(&self) -> PublicKey { unreachable!(); }
+       fn get_channel_signer(&self, _inbound: bool, _channel_value_satoshis: u64) -> EnforcingSigner { unreachable!(); }
+       fn get_secure_random_bytes(&self) -> [u8; 32] { [0; 32] }
+
+       fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::Signer, msgs::DecodeError> {
+               EnforcingSigner::read(&mut io::Cursor::new(reader))
+       }
+       fn sign_invoice(&self, _invoice_preimage: Vec<u8>) -> Result<RecoverableSignature, ()> { unreachable!(); }
+}
+
 pub struct TestChainMonitor<'a> {
-       pub added_monitors: Mutex<Vec<(OutPoint, channelmonitor::ChannelMonitor<EnforcingChannelKeys>)>>,
+       pub added_monitors: Mutex<Vec<(OutPoint, channelmonitor::ChannelMonitor<EnforcingSigner>)>>,
        pub latest_monitor_update_id: Mutex<HashMap<[u8; 32], (OutPoint, u64)>>,
-       pub chain_monitor: chainmonitor::ChainMonitor<EnforcingChannelKeys, &'a TestChainSource, &'a chaininterface::BroadcasterInterface, &'a TestFeeEstimator, &'a TestLogger, &'a channelmonitor::Persist<EnforcingChannelKeys>>,
+       pub chain_monitor: chainmonitor::ChainMonitor<EnforcingSigner, &'a TestChainSource, &'a chaininterface::BroadcasterInterface, &'a TestFeeEstimator, &'a TestLogger, &'a channelmonitor::Persist<EnforcingSigner>>,
+       pub keys_manager: &'a TestKeysInterface,
        pub update_ret: Mutex<Option<Result<(), channelmonitor::ChannelMonitorUpdateErr>>>,
-       // If this is set to Some(), after the next return, we'll always return this until update_ret
-       // is changed:
+       /// If this is set to Some(), after the next return, we'll always return this until update_ret
+       /// is changed:
        pub next_update_ret: Mutex<Option<Result<(), channelmonitor::ChannelMonitorUpdateErr>>>,
+       /// If this is set to Some(), the next update_channel call (not watch_channel) must be a
+       /// ChannelForceClosed event for the given channel_id with should_broadcast set to the given
+       /// boolean.
+       pub expect_channel_force_closed: Mutex<Option<([u8; 32], bool)>>,
 }
 impl<'a> TestChainMonitor<'a> {
-       pub fn new(chain_source: Option<&'a TestChainSource>, broadcaster: &'a chaininterface::BroadcasterInterface, logger: &'a TestLogger, fee_estimator: &'a TestFeeEstimator, persister: &'a channelmonitor::Persist<EnforcingChannelKeys>) -> Self {
+       pub fn new(chain_source: Option<&'a TestChainSource>, broadcaster: &'a chaininterface::BroadcasterInterface, logger: &'a TestLogger, fee_estimator: &'a TestFeeEstimator, persister: &'a channelmonitor::Persist<EnforcingSigner>, keys_manager: &'a TestKeysInterface) -> Self {
                Self {
                        added_monitors: Mutex::new(Vec::new()),
                        latest_monitor_update_id: Mutex::new(HashMap::new()),
                        chain_monitor: chainmonitor::ChainMonitor::new(chain_source, broadcaster, logger, fee_estimator, persister),
+                       keys_manager,
                        update_ret: Mutex::new(None),
                        next_update_ret: Mutex::new(None),
+                       expect_channel_force_closed: Mutex::new(None),
                }
        }
 }
-impl<'a> chain::Watch for TestChainMonitor<'a> {
-       type Keys = EnforcingChannelKeys;
-
-       fn watch_channel(&self, funding_txo: OutPoint, monitor: channelmonitor::ChannelMonitor<EnforcingChannelKeys>) -> Result<(), channelmonitor::ChannelMonitorUpdateErr> {
+impl<'a> chain::Watch<EnforcingSigner> for TestChainMonitor<'a> {
+       fn watch_channel(&self, funding_txo: OutPoint, monitor: channelmonitor::ChannelMonitor<EnforcingSigner>) -> Result<(), channelmonitor::ChannelMonitorUpdateErr> {
                // At every point where we get a monitor update, we should be able to send a useful monitor
                // to a watchtower and disk...
                let mut w = TestVecWriter(Vec::new());
-               monitor.serialize_for_disk(&mut w).unwrap();
-               let new_monitor = <(BlockHash, channelmonitor::ChannelMonitor<EnforcingChannelKeys>)>::read(
-                       &mut ::std::io::Cursor::new(&w.0)).unwrap().1;
+               monitor.write(&mut w).unwrap();
+               let new_monitor = <(BlockHash, channelmonitor::ChannelMonitor<EnforcingSigner>)>::read(
+                       &mut io::Cursor::new(&w.0), self.keys_manager).unwrap().1;
                assert!(new_monitor == monitor);
                self.latest_monitor_update_id.lock().unwrap().insert(funding_txo.to_channel_id(), (funding_txo, monitor.get_latest_update_id()));
                self.added_monitors.lock().unwrap().push((funding_txo, monitor));
@@ -111,18 +137,26 @@ impl<'a> chain::Watch for TestChainMonitor<'a> {
                let mut w = TestVecWriter(Vec::new());
                update.write(&mut w).unwrap();
                assert!(channelmonitor::ChannelMonitorUpdate::read(
-                               &mut ::std::io::Cursor::new(&w.0)).unwrap() == update);
+                               &mut io::Cursor::new(&w.0)).unwrap() == update);
+
+               if let Some(exp) = self.expect_channel_force_closed.lock().unwrap().take() {
+                       assert_eq!(funding_txo.to_channel_id(), exp.0);
+                       assert_eq!(update.updates.len(), 1);
+                       if let channelmonitor::ChannelMonitorUpdateStep::ChannelForceClosed { should_broadcast } = update.updates[0] {
+                               assert_eq!(should_broadcast, exp.1);
+                       } else { panic!(); }
+               }
 
                self.latest_monitor_update_id.lock().unwrap().insert(funding_txo.to_channel_id(), (funding_txo, update.update_id));
                let update_res = self.chain_monitor.update_channel(funding_txo, update);
                // At every point where we get a monitor update, we should be able to send a useful monitor
                // to a watchtower and disk...
-               let monitors = self.chain_monitor.monitors.lock().unwrap();
+               let monitors = self.chain_monitor.monitors.read().unwrap();
                let monitor = monitors.get(&funding_txo).unwrap();
                w.0.clear();
-               monitor.serialize_for_disk(&mut w).unwrap();
-               let new_monitor = <(BlockHash, channelmonitor::ChannelMonitor<EnforcingChannelKeys>)>::read(
-                       &mut ::std::io::Cursor::new(&w.0)).unwrap().1;
+               monitor.write(&mut w).unwrap();
+               let new_monitor = <(BlockHash, channelmonitor::ChannelMonitor<EnforcingSigner>)>::read(
+                       &mut io::Cursor::new(&w.0), self.keys_manager).unwrap().1;
                assert!(new_monitor == *monitor);
                self.added_monitors.lock().unwrap().push((funding_txo, new_monitor));
 
@@ -156,21 +190,30 @@ impl TestPersister {
                *self.update_ret.lock().unwrap() = ret;
        }
 }
-impl channelmonitor::Persist<EnforcingChannelKeys> for TestPersister {
-       fn persist_new_channel(&self, _funding_txo: OutPoint, _data: &channelmonitor::ChannelMonitor<EnforcingChannelKeys>) -> Result<(), channelmonitor::ChannelMonitorUpdateErr> {
+impl<Signer: keysinterface::Sign> channelmonitor::Persist<Signer> for TestPersister {
+       fn persist_new_channel(&self, _funding_txo: OutPoint, _data: &channelmonitor::ChannelMonitor<Signer>) -> Result<(), channelmonitor::ChannelMonitorUpdateErr> {
                self.update_ret.lock().unwrap().clone()
        }
 
-       fn update_persisted_channel(&self, _funding_txo: OutPoint, _update: &channelmonitor::ChannelMonitorUpdate, _data: &channelmonitor::ChannelMonitor<EnforcingChannelKeys>) -> Result<(), channelmonitor::ChannelMonitorUpdateErr> {
+       fn update_persisted_channel(&self, _funding_txo: OutPoint, _update: &channelmonitor::ChannelMonitorUpdate, _data: &channelmonitor::ChannelMonitor<Signer>) -> Result<(), channelmonitor::ChannelMonitorUpdateErr> {
                self.update_ret.lock().unwrap().clone()
        }
 }
 
 pub struct TestBroadcaster {
        pub txn_broadcasted: Mutex<Vec<Transaction>>,
+       pub blocks: Arc<Mutex<Vec<(BlockHeader, u32)>>>,
 }
 impl chaininterface::BroadcasterInterface for TestBroadcaster {
        fn broadcast_transaction(&self, tx: &Transaction) {
+               assert!(tx.lock_time < 1_500_000_000);
+               if tx.lock_time > self.blocks.lock().unwrap().len() as u32 + 1 && tx.lock_time < 500_000_000 {
+                       for inp in tx.input.iter() {
+                               if inp.sequence != 0xffffffff {
+                                       panic!("We should never broadcast a transaction before its locktime ({})!", tx.lock_time);
+                               }
+                       }
+               }
                self.txn_broadcasted.lock().unwrap().push(tx.clone());
        }
 }
@@ -193,7 +236,7 @@ impl msgs::ChannelMessageHandler for TestChannelMessageHandler {
        fn handle_funding_created(&self, _their_node_id: &PublicKey, _msg: &msgs::FundingCreated) {}
        fn handle_funding_signed(&self, _their_node_id: &PublicKey, _msg: &msgs::FundingSigned) {}
        fn handle_funding_locked(&self, _their_node_id: &PublicKey, _msg: &msgs::FundingLocked) {}
-       fn handle_shutdown(&self, _their_node_id: &PublicKey, _msg: &msgs::Shutdown) {}
+       fn handle_shutdown(&self, _their_node_id: &PublicKey, _their_features: &InitFeatures, _msg: &msgs::Shutdown) {}
        fn handle_closing_signed(&self, _their_node_id: &PublicKey, _msg: &msgs::ClosingSigned) {}
        fn handle_update_add_htlc(&self, _their_node_id: &PublicKey, _msg: &msgs::UpdateAddHTLC) {}
        fn handle_update_fulfill_htlc(&self, _their_node_id: &PublicKey, _msg: &msgs::UpdateFulfillHTLC) {}
@@ -202,6 +245,7 @@ impl msgs::ChannelMessageHandler for TestChannelMessageHandler {
        fn handle_commitment_signed(&self, _their_node_id: &PublicKey, _msg: &msgs::CommitmentSigned) {}
        fn handle_revoke_and_ack(&self, _their_node_id: &PublicKey, _msg: &msgs::RevokeAndACK) {}
        fn handle_update_fee(&self, _their_node_id: &PublicKey, _msg: &msgs::UpdateFee) {}
+       fn handle_channel_update(&self, _their_node_id: &PublicKey, _msg: &msgs::ChannelUpdate) {}
        fn handle_announcement_signatures(&self, _their_node_id: &PublicKey, _msg: &msgs::AnnouncementSignatures) {}
        fn handle_channel_reestablish(&self, _their_node_id: &PublicKey, _msg: &msgs::ChannelReestablish) {}
        fn peer_disconnected(&self, _their_node_id: &PublicKey, _no_connection_possible: bool) {}
@@ -237,12 +281,14 @@ fn get_dummy_channel_announcement(short_chan_id: u64) -> msgs::ChannelAnnounceme
                excess_data: Vec::new(),
        };
 
-       msgs::ChannelAnnouncement {
-               node_signature_1: Signature::from(FFISignature::new()),
-               node_signature_2: Signature::from(FFISignature::new()),
-               bitcoin_signature_1: Signature::from(FFISignature::new()),
-               bitcoin_signature_2: Signature::from(FFISignature::new()),
-               contents: unsigned_ann,
+       unsafe {
+               msgs::ChannelAnnouncement {
+                       node_signature_1: Signature::from(FFISignature::new()),
+                       node_signature_2: Signature::from(FFISignature::new()),
+                       bitcoin_signature_1: Signature::from(FFISignature::new()),
+                       bitcoin_signature_2: Signature::from(FFISignature::new()),
+                       contents: unsigned_ann,
+               }
        }
 }
 
@@ -250,7 +296,7 @@ fn get_dummy_channel_update(short_chan_id: u64) -> msgs::ChannelUpdate {
        use bitcoin::secp256k1::ffi::Signature as FFISignature;
        let network = Network::Testnet;
        msgs::ChannelUpdate {
-               signature: Signature::from(FFISignature::new()),
+               signature: Signature::from(unsafe { FFISignature::new() }),
                contents: msgs::UnsignedChannelUpdate {
                        chain_hash: genesis_block(network).header.block_hash(),
                        short_channel_id: short_chan_id,
@@ -316,8 +362,28 @@ impl msgs::RoutingMessageHandler for TestRoutingMessageHandler {
                Vec::new()
        }
 
-       fn should_request_full_sync(&self, _node_id: &PublicKey) -> bool {
-               self.request_full_sync.load(Ordering::Acquire)
+       fn sync_routing_table(&self, _their_node_id: &PublicKey, _init_msg: &msgs::Init) {}
+
+       fn handle_reply_channel_range(&self, _their_node_id: &PublicKey, _msg: msgs::ReplyChannelRange) -> Result<(), msgs::LightningError> {
+               Ok(())
+       }
+
+       fn handle_reply_short_channel_ids_end(&self, _their_node_id: &PublicKey, _msg: msgs::ReplyShortChannelIdsEnd) -> Result<(), msgs::LightningError> {
+               Ok(())
+       }
+
+       fn handle_query_channel_range(&self, _their_node_id: &PublicKey, _msg: msgs::QueryChannelRange) -> Result<(), msgs::LightningError> {
+               Ok(())
+       }
+
+       fn handle_query_short_channel_ids(&self, _their_node_id: &PublicKey, _msg: msgs::QueryShortChannelIds) -> Result<(), msgs::LightningError> {
+               Ok(())
+       }
+}
+
+impl events::MessageSendEventsProvider for TestRoutingMessageHandler {
+       fn get_and_clear_pending_msg_events(&self) -> Vec<events::MessageSendEvent> {
+               vec![]
        }
 }
 
@@ -374,26 +440,30 @@ impl TestLogger {
 impl Logger for TestLogger {
        fn log(&self, record: &Record) {
                *self.lines.lock().unwrap().entry((record.module_path.to_string(), format!("{}", record.args))).or_insert(0) += 1;
-               if self.level >= record.level {
+               if record.level >= self.level {
                        println!("{:<5} {} [{} : {}, {}] {}", record.level.to_string(), self.id, record.module_path, record.file, record.line, record.args);
                }
        }
 }
 
 pub struct TestKeysInterface {
-       backing: keysinterface::KeysManager,
+       pub backing: keysinterface::KeysManager,
        pub override_session_priv: Mutex<Option<[u8; 32]>>,
        pub override_channel_id_priv: Mutex<Option<[u8; 32]>>,
+       pub disable_revocation_policy_check: bool,
+       revoked_commitments: Mutex<HashMap<[u8;32], Arc<Mutex<u64>>>>,
 }
 
 impl keysinterface::KeysInterface for TestKeysInterface {
-       type ChanKeySigner = EnforcingChannelKeys;
+       type Signer = EnforcingSigner;
 
        fn get_node_secret(&self) -> SecretKey { self.backing.get_node_secret() }
        fn get_destination_script(&self) -> Script { self.backing.get_destination_script() }
        fn get_shutdown_pubkey(&self) -> PublicKey { self.backing.get_shutdown_pubkey() }
-       fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> EnforcingChannelKeys {
-               EnforcingChannelKeys::new(self.backing.get_channel_keys(inbound, channel_value_satoshis))
+       fn get_channel_signer(&self, inbound: bool, channel_value_satoshis: u64) -> EnforcingSigner {
+               let keys = self.backing.get_channel_signer(inbound, channel_value_satoshis);
+               let revoked_commitment = self.make_revoked_commitment_cell(keys.commitment_seed);
+               EnforcingSigner::new_with_revoked(keys, revoked_commitment, self.disable_revocation_policy_check)
        }
 
        fn get_secure_random_bytes(&self) -> [u8; 32] {
@@ -410,19 +480,53 @@ impl keysinterface::KeysInterface for TestKeysInterface {
                }
                self.backing.get_secure_random_bytes()
        }
+
+       fn read_chan_signer(&self, buffer: &[u8]) -> Result<Self::Signer, msgs::DecodeError> {
+               let mut reader = io::Cursor::new(buffer);
+
+               let inner: InMemorySigner = Readable::read(&mut reader)?;
+               let revoked_commitment = self.make_revoked_commitment_cell(inner.commitment_seed);
+
+               let last_commitment_number = Readable::read(&mut reader)?;
+
+               Ok(EnforcingSigner {
+                       inner,
+                       last_commitment_number: Arc::new(Mutex::new(last_commitment_number)),
+                       revoked_commitment,
+                       disable_revocation_policy_check: self.disable_revocation_policy_check,
+               })
+       }
+
+       fn sign_invoice(&self, invoice_preimage: Vec<u8>) -> Result<RecoverableSignature, ()> {
+               self.backing.sign_invoice(invoice_preimage)
+       }
 }
 
+
 impl TestKeysInterface {
        pub fn new(seed: &[u8; 32], network: Network) -> Self {
                let now = Duration::from_secs(genesis_block(network).header.time as u64);
                Self {
-                       backing: keysinterface::KeysManager::new(seed, network, now.as_secs(), now.subsec_nanos()),
+                       backing: keysinterface::KeysManager::new(seed, now.as_secs(), now.subsec_nanos()),
                        override_session_priv: Mutex::new(None),
                        override_channel_id_priv: Mutex::new(None),
+                       disable_revocation_policy_check: false,
+                       revoked_commitments: Mutex::new(HashMap::new()),
                }
        }
-       pub fn derive_channel_keys(&self, channel_value_satoshis: u64, user_id_1: u64, user_id_2: u64) -> EnforcingChannelKeys {
-               EnforcingChannelKeys::new(self.backing.derive_channel_keys(channel_value_satoshis, user_id_1, user_id_2))
+       pub fn derive_channel_keys(&self, channel_value_satoshis: u64, id: &[u8; 32]) -> EnforcingSigner {
+               let keys = self.backing.derive_channel_keys(channel_value_satoshis, id);
+               let revoked_commitment = self.make_revoked_commitment_cell(keys.commitment_seed);
+               EnforcingSigner::new_with_revoked(keys, revoked_commitment, self.disable_revocation_policy_check)
+       }
+
+       fn make_revoked_commitment_cell(&self, commitment_seed: [u8; 32]) -> Arc<Mutex<u64>> {
+               let mut revoked_commitments = self.revoked_commitments.lock().unwrap();
+               if !revoked_commitments.contains_key(&commitment_seed) {
+                       revoked_commitments.insert(commitment_seed, Arc::new(Mutex::new(INITIAL_REVOKED_COMMITMENT_NUMBER)));
+               }
+               let cell = revoked_commitments.get(&commitment_seed).unwrap();
+               Arc::clone(cell)
        }
 }
 
@@ -431,6 +535,7 @@ pub struct TestChainSource {
        pub utxo_ret: Mutex<Result<TxOut, chain::AccessError>>,
        pub watched_txn: Mutex<HashSet<(Txid, Script)>>,
        pub watched_outputs: Mutex<HashSet<(OutPoint, Script)>>,
+       expectations: Mutex<Option<VecDeque<OnRegisterOutput>>>,
 }
 
 impl TestChainSource {
@@ -441,8 +546,17 @@ impl TestChainSource {
                        utxo_ret: Mutex::new(Ok(TxOut { value: u64::max_value(), script_pubkey })),
                        watched_txn: Mutex::new(HashSet::new()),
                        watched_outputs: Mutex::new(HashSet::new()),
+                       expectations: Mutex::new(None),
                }
        }
+
+       /// Sets an expectation that [`chain::Filter::register_output`] is called.
+       pub fn expect(&self, expectation: OnRegisterOutput) -> &Self {
+               self.expectations.lock().unwrap()
+                       .get_or_insert_with(|| VecDeque::new())
+                       .push_back(expectation);
+               self
+       }
 }
 
 impl chain::Access for TestChainSource {
@@ -460,7 +574,72 @@ impl chain::Filter for TestChainSource {
                self.watched_txn.lock().unwrap().insert((*txid, script_pubkey.clone()));
        }
 
-       fn register_output(&self, outpoint: &OutPoint, script_pubkey: &Script) {
-               self.watched_outputs.lock().unwrap().insert((*outpoint, script_pubkey.clone()));
+       fn register_output(&self, output: WatchedOutput) -> Option<(usize, Transaction)> {
+               let dependent_tx = match &mut *self.expectations.lock().unwrap() {
+                       None => None,
+                       Some(expectations) => match expectations.pop_front() {
+                               None => {
+                                       panic!("Unexpected register_output: {:?}",
+                                               (output.outpoint, output.script_pubkey));
+                               },
+                               Some(expectation) => {
+                                       assert_eq!(output.outpoint, expectation.outpoint());
+                                       assert_eq!(&output.script_pubkey, expectation.script_pubkey());
+                                       expectation.returns
+                               },
+                       },
+               };
+
+               self.watched_outputs.lock().unwrap().insert((output.outpoint, output.script_pubkey));
+               dependent_tx
+       }
+}
+
+impl Drop for TestChainSource {
+       fn drop(&mut self) {
+               if std::thread::panicking() {
+                       return;
+               }
+
+               if let Some(expectations) = &*self.expectations.lock().unwrap() {
+                       if !expectations.is_empty() {
+                               panic!("Unsatisfied expectations: {:?}", expectations);
+                       }
+               }
+       }
+}
+
+/// An expectation that [`chain::Filter::register_output`] was called with a transaction output and
+/// returns an optional dependent transaction that spends the output in the same block.
+pub struct OnRegisterOutput {
+       /// The transaction output to register.
+       pub with: TxOutReference,
+
+       /// A dependent transaction spending the output along with its position in the block.
+       pub returns: Option<(usize, Transaction)>,
+}
+
+/// A transaction output as identified by an index into a transaction's output list.
+pub struct TxOutReference(pub Transaction, pub usize);
+
+impl OnRegisterOutput {
+       fn outpoint(&self) -> OutPoint {
+               let txid = self.with.0.txid();
+               let index = self.with.1 as u16;
+               OutPoint { txid, index }
+       }
+
+       fn script_pubkey(&self) -> &Script {
+               let index = self.with.1;
+               &self.with.0.output[index].script_pubkey
+       }
+}
+
+impl core::fmt::Debug for OnRegisterOutput {
+       fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+               f.debug_struct("OnRegisterOutput")
+                       .field("outpoint", &self.outpoint())
+                       .field("script_pubkey", self.script_pubkey())
+                       .finish()
        }
 }