Introduce mockable ChainSync object for testing (#12480)

* Introduce mockable `ChainSync` object for testing

`mockall` allows to mock `ChainSync` and to verify that the calls made
to `ChaiSync` are firstly executed at all, that they're executed in
correct order and with correct parameters.

This allows to verify, e.g., that delegating calls directly to
`ChainSync` from `NetworkService` still calls the correct functions with
correct arguments even if `Protocol` middleman is removed.

* Add Cargo.lock

* Fix tests

* Update client/network/Cargo.toml

Co-authored-by: Bastian Köcher <git@kchr.de>

* Update Cargo.lock

* Fix clippy and documentation

Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: parity-processbot <>

substrate/Cargo.lock

@@ -1717,6 +1717,12 @@ version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fea41bba32d969b513997752735605054bc0dfa92b4c56bf1189f2e174be7a10"
 
+[[package]]
+name = "downcast"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1435fa1053d8b2fbbe9be7e97eca7f33d37b28409959813daefc1446a14247f1"
+
 [[package]]
 name = "downcast-rs"
 version = "1.2.0"
@@ -2093,6 +2099,15 @@ dependencies = [
  "miniz_oxide",
 ]
 
+[[package]]
+name = "float-cmp"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "98de4bbd547a563b716d8dfa9aad1cb19bfab00f4fa09a6a4ed21dbcf44ce9c4"
+dependencies = [
+ "num-traits",
+]
+
 [[package]]
 name = "fnv"
 version = "1.0.7"
@@ -2116,6 +2131,12 @@ dependencies = [
  "percent-encoding",
 ]
 
+[[package]]
+name = "fragile"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85dcb89d2b10c5f6133de2efd8c11959ce9dbb46a2f7a4cab208c4eeda6ce1ab"
+
 [[package]]
 name = "frame-benchmarking"
 version = "4.0.0-dev"
@@ -4395,6 +4416,33 @@ dependencies = [
  "windows-sys 0.36.1",
 ]
 
+[[package]]
+name = "mockall"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2be9a9090bc1cac2930688fa9478092a64c6a92ddc6ae0692d46b37d9cab709"
+dependencies = [
+ "cfg-if 1.0.0",
+ "downcast",
+ "fragile",
+ "lazy_static",
+ "mockall_derive",
+ "predicates",
+ "predicates-tree",
+]
+
+[[package]]
+name = "mockall_derive"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "86d702a0530a0141cf4ed147cf5ec7be6f2c187d4e37fcbefc39cf34116bfe8f"
+dependencies = [
+ "cfg-if 1.0.0",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "more-asserts"
 version = "0.2.1"
@@ -4970,6 +5018,12 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "normalize-line-endings"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "61807f77802ff30975e01f4f071c8ba10c022052f98b3294119f3e615d13e5be"
+
 [[package]]
 name = "num-bigint"
 version = "0.2.6"
@@ -6942,8 +6996,11 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c143348f141cc87aab5b950021bac6145d0e5ae754b0591de23244cee42c9308"
 dependencies = [
  "difflib",
+ "float-cmp",
  "itertools",
+ "normalize-line-endings",
  "predicates-core",
+ "regex",
 ]
 
 [[package]]
@@ -8586,6 +8643,7 @@ dependencies = [
  "libp2p",
  "log",
  "lru",
+ "mockall",
  "parity-scale-codec",
  "prost 0.11.0",
  "prost-build 0.11.1",

substrate/client/network/common/src/sync.rs

@@ -269,12 +269,14 @@ pub trait ChainSync<Block: BlockT>: Send {
 	);
 
 	/// Get an iterator over all scheduled justification requests.
-	fn justification_requests(
-		&mut self,
-	) -> Box<dyn Iterator<Item = (PeerId, BlockRequest<Block>)> + '_>;
+	fn justification_requests<'a>(
+		&'a mut self,
+	) -> Box<dyn Iterator<Item = (PeerId, BlockRequest<Block>)> + 'a>;
 
 	/// Get an iterator over all block requests of all peers.
-	fn block_requests(&mut self) -> Box<dyn Iterator<Item = (&PeerId, BlockRequest<Block>)> + '_>;
+	fn block_requests<'a>(
+		&'a mut self,
+	) -> Box<dyn Iterator<Item = (PeerId, BlockRequest<Block>)> + 'a>;
 
 	/// Get a state request, if any.
 	fn state_request(&mut self) -> Option<(PeerId, OpaqueStateRequest)>;
@@ -359,9 +361,9 @@ pub trait ChainSync<Block: BlockT>: Send {
 	///
 	/// If [`PollBlockAnnounceValidation::ImportHeader`] is returned, then the caller MUST try to
 	/// import passed header (call `on_block_data`). The network request isn't sent in this case.
-	fn poll_block_announce_validation(
+	fn poll_block_announce_validation<'a>(
 		&mut self,
-		cx: &mut std::task::Context,
+		cx: &mut std::task::Context<'a>,
 	) -> Poll<PollBlockAnnounceValidation<Block::Header>>;
 
 	/// Call when a peer has disconnected.

substrate/client/network/src/protocol.rs

@@ -1440,7 +1440,7 @@ where
 		for (id, request) in self
 			.chain_sync
 			.block_requests()
-			.map(|(peer_id, request)| (*peer_id, request))
+			.map(|(peer_id, request)| (peer_id, request))
 			.collect::<Vec<_>>()
 		{
 			let event =

substrate/client/network/src/service.rs

@@ -92,6 +92,8 @@ use std::{
 
 pub use behaviour::{InboundFailure, OutboundFailure, ResponseFailure};
 
+#[cfg(test)]
+mod chainsync_tests;
 mod metrics;
 mod out_events;
 #[cfg(test)]

substrate/client/network/src/service/chainsync_tests.rs

@@ -0,0 +1,339 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+use crate::{config, NetworkWorker};
+
+use futures::prelude::*;
+use libp2p::PeerId;
+use sc_block_builder::BlockBuilderProvider;
+use sc_client_api::{BlockBackend, HeaderBackend};
+use sc_consensus::JustificationSyncLink;
+use sc_network_common::{
+	config::{
+		NonDefaultSetConfig, NonReservedPeerMode, NotificationHandshake, ProtocolId, SetConfig,
+		TransportConfig,
+	},
+	protocol::role::Roles,
+	service::NetworkSyncForkRequest,
+	sync::{message::BlockAnnouncesHandshake, ChainSync as ChainSyncT, SyncState, SyncStatus},
+};
+use sc_network_light::light_client_requests::handler::LightClientRequestHandler;
+use sc_network_sync::{
+	block_request_handler::BlockRequestHandler, mock::MockChainSync,
+	state_request_handler::StateRequestHandler,
+};
+use sp_core::H256;
+use sp_runtime::{
+	generic::BlockId,
+	traits::{Block as BlockT, Header as _, Zero},
+};
+use std::{iter, sync::Arc, task::Poll};
+use substrate_test_runtime_client::{TestClientBuilder, TestClientBuilderExt as _};
+
+type TestNetworkWorker = NetworkWorker<
+	substrate_test_runtime_client::runtime::Block,
+	substrate_test_runtime_client::runtime::Hash,
+	substrate_test_runtime_client::TestClient,
+>;
+
+const BLOCK_ANNOUNCE_PROTO_NAME: &str = "/block-announces";
+const PROTOCOL_NAME: &str = "/foo";
+
+fn make_network(
+	chain_sync: Box<dyn ChainSyncT<substrate_test_runtime_client::runtime::Block>>,
+	client: Arc<substrate_test_runtime_client::TestClient>,
+) -> (TestNetworkWorker, Arc<substrate_test_runtime_client::TestClient>) {
+	let network_config = config::NetworkConfiguration {
+		extra_sets: vec![NonDefaultSetConfig {
+			notifications_protocol: PROTOCOL_NAME.into(),
+			fallback_names: Vec::new(),
+			max_notification_size: 1024 * 1024,
+			handshake: None,
+			set_config: Default::default(),
+		}],
+		listen_addresses: vec![config::build_multiaddr![Memory(rand::random::<u64>())]],
+		transport: TransportConfig::MemoryOnly,
+		..config::NetworkConfiguration::new_local()
+	};
+
+	#[derive(Clone)]
+	struct PassThroughVerifier(bool);
+
+	#[async_trait::async_trait]
+	impl<B: BlockT> sc_consensus::Verifier<B> for PassThroughVerifier {
+		async fn verify(
+			&mut self,
+			mut block: sc_consensus::BlockImportParams<B, ()>,
+		) -> Result<
+			(
+				sc_consensus::BlockImportParams<B, ()>,
+				Option<Vec<(sp_blockchain::well_known_cache_keys::Id, Vec<u8>)>>,
+			),
+			String,
+		> {
+			let maybe_keys = block
+				.header
+				.digest()
+				.log(|l| {
+					l.try_as_raw(sp_runtime::generic::OpaqueDigestItemId::Consensus(b"aura"))
+						.or_else(|| {
+							l.try_as_raw(sp_runtime::generic::OpaqueDigestItemId::Consensus(
+								b"babe",
+							))
+						})
+				})
+				.map(|blob| {
+					vec![(sp_blockchain::well_known_cache_keys::AUTHORITIES, blob.to_vec())]
+				});
+
+			block.finalized = self.0;
+			block.fork_choice = Some(sc_consensus::ForkChoiceStrategy::LongestChain);
+			Ok((block, maybe_keys))
+		}
+	}
+
+	let import_queue = Box::new(sc_consensus::BasicQueue::new(
+		PassThroughVerifier(false),
+		Box::new(client.clone()),
+		None,
+		&sp_core::testing::TaskExecutor::new(),
+		None,
+	));
+
+	let protocol_id = ProtocolId::from("/test-protocol-name");
+
+	let fork_id = Some(String::from("test-fork-id"));
+
+	let block_request_protocol_config = {
+		let (handler, protocol_config) =
+			BlockRequestHandler::new(&protocol_id, None, client.clone(), 50);
+		async_std::task::spawn(handler.run().boxed());
+		protocol_config
+	};
+
+	let state_request_protocol_config = {
+		let (handler, protocol_config) =
+			StateRequestHandler::new(&protocol_id, None, client.clone(), 50);
+		async_std::task::spawn(handler.run().boxed());
+		protocol_config
+	};
+
+	let light_client_request_protocol_config = {
+		let (handler, protocol_config) =
+			LightClientRequestHandler::new(&protocol_id, None, client.clone());
+		async_std::task::spawn(handler.run().boxed());
+		protocol_config
+	};
+
+	let block_announce_config = NonDefaultSetConfig {
+		notifications_protocol: BLOCK_ANNOUNCE_PROTO_NAME.into(),
+		fallback_names: vec![],
+		max_notification_size: 1024 * 1024,
+		handshake: Some(NotificationHandshake::new(BlockAnnouncesHandshake::<
+			substrate_test_runtime_client::runtime::Block,
+		>::build(
+			Roles::from(&config::Role::Full),
+			client.info().best_number,
+			client.info().best_hash,
+			client
+				.block_hash(Zero::zero())
+				.ok()
+				.flatten()
+				.expect("Genesis block exists; qed"),
+		))),
+		set_config: SetConfig {
+			in_peers: 0,
+			out_peers: 0,
+			reserved_nodes: Vec::new(),
+			non_reserved_mode: NonReservedPeerMode::Deny,
+		},
+	};
+
+	let worker = NetworkWorker::new(config::Params {
+		block_announce_config,
+		role: config::Role::Full,
+		executor: None,
+		network_config,
+		chain: client.clone(),
+		protocol_id,
+		fork_id,
+		import_queue,
+		chain_sync,
+		metrics_registry: None,
+		block_request_protocol_config,
+		state_request_protocol_config,
+		light_client_request_protocol_config,
+		warp_sync_protocol_config: None,
+		request_response_protocol_configs: Vec::new(),
+	})
+	.unwrap();
+
+	(worker, client)
+}
+
+fn set_default_expecations_no_peers(
+	chain_sync: &mut MockChainSync<substrate_test_runtime_client::runtime::Block>,
+) {
+	chain_sync.expect_block_requests().returning(|| Box::new(iter::empty()));
+	chain_sync.expect_state_request().returning(|| None);
+	chain_sync.expect_justification_requests().returning(|| Box::new(iter::empty()));
+	chain_sync.expect_warp_sync_request().returning(|| None);
+	chain_sync.expect_poll_block_announce_validation().returning(|_| Poll::Pending);
+	chain_sync.expect_status().returning(|| SyncStatus {
+		state: SyncState::Idle,
+		best_seen_block: None,
+		num_peers: 0u32,
+		queued_blocks: 0u32,
+		state_sync: None,
+		warp_sync: None,
+	});
+}
+
+#[async_std::test]
+async fn normal_network_poll_no_peers() {
+	let client = Arc::new(TestClientBuilder::with_default_backend().build_with_longest_chain().0);
+	let mut chain_sync =
+		Box::new(MockChainSync::<substrate_test_runtime_client::runtime::Block>::new());
+	set_default_expecations_no_peers(&mut chain_sync);
+
+	let (mut network, _) = make_network(chain_sync, client);
+
+	// poll the network once
+	futures::future::poll_fn(|cx| {
+		let _ = network.poll_unpin(cx);
+		Poll::Ready(())
+	})
+	.await;
+}
+
+#[async_std::test]
+async fn request_justification() {
+	let client = Arc::new(TestClientBuilder::with_default_backend().build_with_longest_chain().0);
+	let mut chain_sync =
+		Box::new(MockChainSync::<substrate_test_runtime_client::runtime::Block>::new());
+
+	let hash = H256::random();
+	let number = 1337u64;
+
+	chain_sync
+		.expect_request_justification()
+		.withf(move |in_hash, in_number| &hash == in_hash && &number == in_number)
+		.once()
+		.returning(|_, _| ());
+
+	set_default_expecations_no_peers(&mut chain_sync);
+	let (mut network, _) = make_network(chain_sync, client);
+
+	// send "request justifiction" message and poll the network
+	network.service().request_justification(&hash, number);
+
+	futures::future::poll_fn(|cx| {
+		let _ = network.poll_unpin(cx);
+		Poll::Ready(())
+	})
+	.await;
+}
+
+#[async_std::test]
+async fn clear_justification_requests(&mut self) {
+	let client = Arc::new(TestClientBuilder::with_default_backend().build_with_longest_chain().0);
+	let mut chain_sync =
+		Box::new(MockChainSync::<substrate_test_runtime_client::runtime::Block>::new());
+
+	chain_sync.expect_clear_justification_requests().once().returning(|| ());
+
+	set_default_expecations_no_peers(&mut chain_sync);
+	let (mut network, _) = make_network(chain_sync, client);
+
+	// send "request justifiction" message and poll the network
+	network.service().clear_justification_requests();
+
+	futures::future::poll_fn(|cx| {
+		let _ = network.poll_unpin(cx);
+		Poll::Ready(())
+	})
+	.await;
+}
+
+#[async_std::test]
+async fn set_sync_fork_request() {
+	let client = Arc::new(TestClientBuilder::with_default_backend().build_with_longest_chain().0);
+	let mut chain_sync =
+		Box::new(MockChainSync::<substrate_test_runtime_client::runtime::Block>::new());
+
+	let hash = H256::random();
+	let number = 1337u64;
+	let peers = (0..3).map(|_| PeerId::random()).collect::<Vec<_>>();
+	let copy_peers = peers.clone();
+
+	chain_sync
+		.expect_set_sync_fork_request()
+		.withf(move |in_peers, in_hash, in_number| {
+			&peers == in_peers && &hash == in_hash && &number == in_number
+		})
+		.once()
+		.returning(|_, _, _| ());
+
+	set_default_expecations_no_peers(&mut chain_sync);
+	let (mut network, _) = make_network(chain_sync, client);
+
+	// send "set sync fork request" message and poll the network
+	network.service().set_sync_fork_request(copy_peers, hash, number);
+
+	futures::future::poll_fn(|cx| {
+		let _ = network.poll_unpin(cx);
+		Poll::Ready(())
+	})
+	.await;
+}
+
+#[async_std::test]
+async fn on_block_finalized() {
+	let client = Arc::new(TestClientBuilder::with_default_backend().build_with_longest_chain().0);
+	let mut chain_sync =
+		Box::new(MockChainSync::<substrate_test_runtime_client::runtime::Block>::new());
+
+	let at = client.header(&BlockId::Hash(client.info().best_hash)).unwrap().unwrap().hash();
+	let block = client
+		.new_block_at(&BlockId::Hash(at), Default::default(), false)
+		.unwrap()
+		.build()
+		.unwrap()
+		.block;
+	let header = block.header.clone();
+	let block_number = *header.number();
+	let hash = block.hash();
+
+	chain_sync
+		.expect_on_block_finalized()
+		.withf(move |in_hash, in_number| &hash == in_hash && &block_number == in_number)
+		.once()
+		.returning(|_, _| ());
+
+	set_default_expecations_no_peers(&mut chain_sync);
+	let (mut network, _) = make_network(chain_sync, client);
+
+	// send "set sync fork request" message and poll the network
+	network.on_block_finalized(hash, header);
+
+	futures::future::poll_fn(|cx| {
+		let _ = network.poll_unpin(cx);
+		Poll::Ready(())
+	})
+	.await;
+}

substrate/client/network/sync/Cargo.toml

@@ -25,6 +25,7 @@ futures = "0.3.21"
 libp2p = "0.46.1"
 log = "0.4.17"
 lru = "0.7.5"
+mockall = "0.11.2"
 prost = "0.11"
 smallvec = "1.8.0"
 thiserror = "1.0"

substrate/client/network/sync/src/lib.rs

@@ -30,6 +30,7 @@
 
 pub mod block_request_handler;
 pub mod blocks;
+pub mod mock;
 mod schema;
 pub mod state;
 pub mod state_request_handler;
@@ -643,9 +644,9 @@ where
 			.extend(peers);
 	}
 
-	fn justification_requests(
-		&mut self,
-	) -> Box<dyn Iterator<Item = (PeerId, BlockRequest<B>)> + '_> {
+	fn justification_requests<'a>(
+		&'a mut self,
+	) -> Box<dyn Iterator<Item = (PeerId, BlockRequest<B>)> + 'a> {
 		let peers = &mut self.peers;
 		let mut matcher = self.extra_justifications.matcher();
 		Box::new(std::iter::from_fn(move || {
@@ -670,7 +671,9 @@ where
 		}))
 	}
 
-	fn block_requests(&mut self) -> Box<dyn Iterator<Item = (&PeerId, BlockRequest<B>)> + '_> {
+	fn block_requests<'a>(
+		&'a mut self,
+	) -> Box<dyn Iterator<Item = (PeerId, BlockRequest<B>)> + 'a> {
 		if self.mode == SyncMode::Warp {
 			return Box::new(std::iter::once(self.warp_target_block_request()).flatten())
 		}
@@ -695,8 +698,8 @@ where
 		let allowed_requests = self.allowed_requests.take();
 		let max_parallel = if major_sync { 1 } else { self.max_parallel_downloads };
 		let gap_sync = &mut self.gap_sync;
-		let iter = self.peers.iter_mut().filter_map(move |(id, peer)| {
-			if !peer.state.is_available() || !allowed_requests.contains(id) {
+		let iter = self.peers.iter_mut().filter_map(move |(&id, peer)| {
+			if !peer.state.is_available() || !allowed_requests.contains(&id) {
 				return None
 			}
 
@@ -725,7 +728,7 @@ where
 				};
 				Some((id, ancestry_request::<B>(current)))
 			} else if let Some((range, req)) = peer_block_request(
-				id,
+				&id,
 				peer,
 				blocks,
 				attrs,
@@ -744,7 +747,7 @@ where
 				);
 				Some((id, req))
 			} else if let Some((hash, req)) =
-				fork_sync_request(id, fork_targets, best_queued, last_finalized, attrs, |hash| {
+				fork_sync_request(&id, fork_targets, best_queued, last_finalized, attrs, |hash| {
 					if queue.contains(hash) {
 						BlockStatus::Queued
 					} else {
@@ -756,7 +759,7 @@ where
 				Some((id, req))
 			} else if let Some((range, req)) = gap_sync.as_mut().and_then(|sync| {
 				peer_gap_block_request(
-					id,
+					&id,
 					peer,
 					&mut sync.blocks,
 					attrs,
@@ -2216,7 +2219,7 @@ where
 	}
 
 	/// Generate block request for downloading of the target block body during warp sync.
-	fn warp_target_block_request(&mut self) -> Option<(&PeerId, BlockRequest<B>)> {
+	fn warp_target_block_request(&mut self) -> Option<(PeerId, BlockRequest<B>)> {
 		if let Some(sync) = &self.warp_sync {
 			if self.allowed_requests.is_empty() ||
 				sync.is_complete() ||
@@ -2234,7 +2237,7 @@ where
 						trace!(target: "sync", "New warp target block request for {}", id);
 						peer.state = PeerSyncState::DownloadingWarpTargetBlock;
 						self.allowed_requests.clear();
-						return Some((id, request))
+						return Some((*id, request))
 					}
 				}
 			}
@@ -2482,7 +2485,7 @@ fn fork_sync_request<B: BlockT>(
 		true
 	});
 	for (hash, r) in targets {
-		if !r.peers.contains(id) {
+		if !r.peers.contains(&id) {
 			continue
 		}
 		// Download the fork only if it is behind or not too far ahead our tip of the chain
@@ -2740,7 +2743,7 @@ mod test {
 
 		// we wil send block requests to these peers
 		// for these blocks we don't know about
-		assert!(sync.block_requests().all(|(p, _)| { *p == peer_id1 || *p == peer_id2 }));
+		assert!(sync.block_requests().all(|(p, _)| { p == peer_id1 || p == peer_id2 }));
 
 		// add a new peer at a known block
 		sync.new_peer(peer_id3, b1_hash, b1_number).unwrap();
@@ -2835,7 +2838,7 @@ mod test {
 		log::trace!(target: "sync", "Requests: {:?}", requests);
 
 		assert_eq!(1, requests.len());
-		assert_eq!(peer, requests[0].0);
+		assert_eq!(*peer, requests[0].0);
 
 		let request = requests[0].1.clone();
 
@@ -3065,9 +3068,9 @@ mod test {
 		send_block_announce(best_block.header().clone(), &peer_id2, &mut sync);
 
 		let (peer1_req, peer2_req) = sync.block_requests().fold((None, None), |res, req| {
-			if req.0 == &peer_id1 {
+			if req.0 == peer_id1 {
 				(Some(req.1), res.1)
-			} else if req.0 == &peer_id2 {
+			} else if req.0 == peer_id2 {
 				(res.0, Some(req.1))
 			} else {
 				panic!("Unexpected req: {:?}", req)

substrate/client/network/sync/src/mock.rs

@@ -0,0 +1,118 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+//! Contains a mock implementation of `ChainSync` that can be used
+//! for testing calls made to `ChainSync`.
+
+use futures::task::Poll;
+use libp2p::PeerId;
+use sc_consensus::{BlockImportError, BlockImportStatus};
+use sc_network_common::sync::{
+	message::{BlockAnnounce, BlockData, BlockRequest, BlockResponse},
+	warp::{EncodedProof, WarpProofRequest},
+	BadPeer, ChainSync as ChainSyncT, Metrics, OnBlockData, OnBlockJustification, OnStateData,
+	OpaqueBlockRequest, OpaqueBlockResponse, OpaqueStateRequest, OpaqueStateResponse, PeerInfo,
+	PollBlockAnnounceValidation, SyncStatus,
+};
+use sp_runtime::traits::{Block as BlockT, NumberFor};
+
+mockall::mock! {
+	pub ChainSync<Block: BlockT> {}
+
+	impl<Block: BlockT> ChainSyncT<Block> for ChainSync<Block> {
+		fn peer_info(&self, who: &PeerId) -> Option<PeerInfo<Block>>;
+		fn status(&self) -> SyncStatus<Block>;
+		fn num_sync_requests(&self) -> usize;
+		fn num_downloaded_blocks(&self) -> usize;
+		fn num_peers(&self) -> usize;
+		fn new_peer(
+			&mut self,
+			who: PeerId,
+			best_hash: Block::Hash,
+			best_number: NumberFor<Block>,
+		) -> Result<Option<BlockRequest<Block>>, BadPeer>;
+		fn update_chain_info(&mut self, best_hash: &Block::Hash, best_number: NumberFor<Block>);
+		fn request_justification(&mut self, hash: &Block::Hash, number: NumberFor<Block>);
+		fn clear_justification_requests(&mut self);
+		fn set_sync_fork_request(
+			&mut self,
+			peers: Vec<PeerId>,
+			hash: &Block::Hash,
+			number: NumberFor<Block>,
+		);
+		fn justification_requests<'a>(
+			&'a mut self,
+		) -> Box<dyn Iterator<Item = (PeerId, BlockRequest<Block>)> + 'a>;
+		fn block_requests<'a>(&'a mut self) -> Box<dyn Iterator<Item = (PeerId, BlockRequest<Block>)> + 'a>;
+		fn state_request(&mut self) -> Option<(PeerId, OpaqueStateRequest)>;
+		fn warp_sync_request(&mut self) -> Option<(PeerId, WarpProofRequest<Block>)>;
+		fn on_block_data(
+			&mut self,
+			who: &PeerId,
+			request: Option<BlockRequest<Block>>,
+			response: BlockResponse<Block>,
+		) -> Result<OnBlockData<Block>, BadPeer>;
+		fn on_state_data(
+			&mut self,
+			who: &PeerId,
+			response: OpaqueStateResponse,
+		) -> Result<OnStateData<Block>, BadPeer>;
+		fn on_warp_sync_data(&mut self, who: &PeerId, response: EncodedProof) -> Result<(), BadPeer>;
+		fn on_block_justification(
+			&mut self,
+			who: PeerId,
+			response: BlockResponse<Block>,
+		) -> Result<OnBlockJustification<Block>, BadPeer>;
+		fn on_blocks_processed(
+			&mut self,
+			imported: usize,
+			count: usize,
+			results: Vec<(Result<BlockImportStatus<NumberFor<Block>>, BlockImportError>, Block::Hash)>,
+		) -> Box<dyn Iterator<Item = Result<(PeerId, BlockRequest<Block>), BadPeer>>>;
+		fn on_justification_import(
+			&mut self,
+			hash: Block::Hash,
+			number: NumberFor<Block>,
+			success: bool,
+		);
+		fn on_block_finalized(&mut self, hash: &Block::Hash, number: NumberFor<Block>);
+		fn push_block_announce_validation(
+			&mut self,
+			who: PeerId,
+			hash: Block::Hash,
+			announce: BlockAnnounce<Block::Header>,
+			is_best: bool,
+		);
+		fn poll_block_announce_validation<'a>(
+			&mut self,
+			cx: &mut std::task::Context<'a>,
+		) -> Poll<PollBlockAnnounceValidation<Block::Header>>;
+		fn peer_disconnected(&mut self, who: &PeerId) -> Option<OnBlockData<Block>>;
+		fn metrics(&self) -> Metrics;
+		fn create_opaque_block_request(&self, request: &BlockRequest<Block>) -> OpaqueBlockRequest;
+		fn encode_block_request(&self, request: &OpaqueBlockRequest) -> Result<Vec<u8>, String>;
+		fn decode_block_response(&self, response: &[u8]) -> Result<OpaqueBlockResponse, String>;
+		fn block_response_into_blocks(
+			&self,
+			request: &BlockRequest<Block>,
+			response: OpaqueBlockResponse,
+		) -> Result<Vec<BlockData<Block>>, String>;
+		fn encode_state_request(&self, request: &OpaqueStateRequest) -> Result<Vec<u8>, String>;
+		fn decode_state_response(&self, response: &[u8]) -> Result<OpaqueStateResponse, String>;
+	}
+}