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 <>

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.

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 =

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)]