lib.rs

			&Sr25519Keyring::Bob.pair().into(),
		));

		assert_matches!(noted, NotedStatement::Fresh(_));

		// note C (new validator)
		let noted = head_data.note_statement(SignedFullStatement::sign(
			Statement::Seconded(candidate_c.clone()),
			&signing_context,
			1,
			&Sr25519Keyring::Bob.pair().into(),
		));

		assert_matches!(noted, NotedStatement::Fresh(_));
	}

	#[test]
	fn note_local_works() {
		let hash_a: Hash = [1; 32].into();
		let hash_b: Hash = [2; 32].into();

		let mut per_peer_tracker = VcPerPeerTracker::default();
		per_peer_tracker.note_local(hash_a.clone());
		per_peer_tracker.note_local(hash_b.clone());

		assert!(per_peer_tracker.local_observed.contains(&hash_a));
		assert!(per_peer_tracker.local_observed.contains(&hash_b));

		assert!(!per_peer_tracker.remote_observed.contains(&hash_a));
		assert!(!per_peer_tracker.remote_observed.contains(&hash_b));
	}

	#[test]
	fn note_remote_works() {
		let hash_a: Hash = [1; 32].into();
		let hash_b: Hash = [2; 32].into();
		let hash_c: Hash = [3; 32].into();

		let mut per_peer_tracker = VcPerPeerTracker::default();
		assert!(per_peer_tracker.note_remote(hash_a.clone()));
		assert!(per_peer_tracker.note_remote(hash_b.clone()));
		assert!(!per_peer_tracker.note_remote(hash_c.clone()));

		assert!(per_peer_tracker.remote_observed.contains(&hash_a));
		assert!(per_peer_tracker.remote_observed.contains(&hash_b));
		assert!(!per_peer_tracker.remote_observed.contains(&hash_c));

		assert!(!per_peer_tracker.local_observed.contains(&hash_a));
		assert!(!per_peer_tracker.local_observed.contains(&hash_b));
		assert!(!per_peer_tracker.local_observed.contains(&hash_c));
	}

	#[test]
	fn per_peer_relay_parent_knowledge_send() {
		let mut knowledge = PeerRelayParentKnowledge::default();

		let hash_a: Hash = [1; 32].into();

		// Sending an un-pinned statement should not work and should have no effect.
		assert!(knowledge.send(&(CompactStatement::Valid(hash_a), 0)).is_none());
		assert!(!knowledge.known_candidates.contains(&hash_a));
		assert!(knowledge.sent_statements.is_empty());
		assert!(knowledge.received_statements.is_empty());
		assert!(knowledge.seconded_counts.is_empty());
		assert!(knowledge.received_message_count.is_empty());

		// Make the peer aware of the candidate.
		assert_eq!(knowledge.send(&(CompactStatement::Candidate(hash_a), 0)), Some(true));
		assert_eq!(knowledge.send(&(CompactStatement::Candidate(hash_a), 1)), Some(false));
		assert!(knowledge.known_candidates.contains(&hash_a));
		assert_eq!(knowledge.sent_statements.len(), 2);
		assert!(knowledge.received_statements.is_empty());
		assert_eq!(knowledge.seconded_counts.len(), 2);
		assert!(knowledge.received_message_count.get(&hash_a).is_none());

		// And now it should accept the dependent message.
		assert_eq!(knowledge.send(&(CompactStatement::Valid(hash_a), 0)), Some(false));
		assert!(knowledge.known_candidates.contains(&hash_a));
		assert_eq!(knowledge.sent_statements.len(), 3);
		assert!(knowledge.received_statements.is_empty());
		assert_eq!(knowledge.seconded_counts.len(), 2);
		assert!(knowledge.received_message_count.get(&hash_a).is_none());
	}

	#[test]
	fn cant_send_after_receiving() {
		let mut knowledge = PeerRelayParentKnowledge::default();

		let hash_a: Hash = [1; 32].into();
		assert!(knowledge.receive(&(CompactStatement::Candidate(hash_a), 0), 3).unwrap());
		assert!(knowledge.send(&(CompactStatement::Candidate(hash_a), 0)).is_none());
	}

	#[test]
	fn per_peer_relay_parent_knowledge_receive() {
		let mut knowledge = PeerRelayParentKnowledge::default();

		let hash_a: Hash = [1; 32].into();

		assert_eq!(
			knowledge.receive(&(CompactStatement::Valid(hash_a), 0), 3),
			Err(COST_UNEXPECTED_STATEMENT),
		);

		assert_eq!(
			knowledge.receive(&(CompactStatement::Candidate(hash_a), 0), 3),
			Ok(true),
		);

		// Push statements up to the flood limit.
		assert_eq!(
			knowledge.receive(&(CompactStatement::Valid(hash_a), 1), 3),
			Ok(false),
		);

		assert!(knowledge.known_candidates.contains(&hash_a));
		assert_eq!(*knowledge.received_message_count.get(&hash_a).unwrap(), 2);

		assert_eq!(
			knowledge.receive(&(CompactStatement::Valid(hash_a), 2), 3),
			Ok(false),
		);

		assert_eq!(*knowledge.received_message_count.get(&hash_a).unwrap(), 3);

		assert_eq!(
			knowledge.receive(&(CompactStatement::Valid(hash_a), 7), 3),
			Err(COST_APPARENT_FLOOD),
		);

		assert_eq!(*knowledge.received_message_count.get(&hash_a).unwrap(), 3);
		assert_eq!(knowledge.received_statements.len(), 3); // number of prior `Ok`s.

		// Now make sure that the seconding limit is respected.
		let hash_b: Hash = [2; 32].into();
		let hash_c: Hash = [3; 32].into();

		assert_eq!(
			knowledge.receive(&(CompactStatement::Candidate(hash_b), 0), 3),
			Ok(true),
		);

		assert_eq!(
			knowledge.receive(&(CompactStatement::Candidate(hash_c), 0), 3),
			Err(COST_UNEXPECTED_STATEMENT),
		);

		// Last, make sure that already-known statements are disregarded.
		assert_eq!(
			knowledge.receive(&(CompactStatement::Valid(hash_a), 2), 3),
			Err(COST_DUPLICATE_STATEMENT),
		);

		assert_eq!(
			knowledge.receive(&(CompactStatement::Candidate(hash_b), 0), 3),
			Err(COST_DUPLICATE_STATEMENT),
		);
	}

	#[test]
	fn peer_view_update_sends_messages() {
		let hash_a = [1; 32].into();
		let hash_b = [2; 32].into();
		let hash_c = [3; 32].into();

		let candidate = {
			let mut c = CommittedCandidateReceipt::default();
			c.descriptor.relay_parent = hash_c;
			c.descriptor.para_id = 1.into();
			c
		};
		let candidate_hash = candidate.hash();

		let old_view = View(vec![hash_a, hash_b]);
		let new_view = View(vec![hash_b, hash_c]);

		let mut active_heads = HashMap::new();
		let validators = vec![
			Sr25519Keyring::Alice.public().into(),
			Sr25519Keyring::Bob.public().into(),
			Sr25519Keyring::Charlie.public().into(),
		];

		let session_index = 1;
		let signing_context = SigningContext {
			parent_hash: hash_c,
			session_index,
		};

		let new_head_data = {
			let mut data = ActiveHeadData::new(validators, session_index);

			let noted = data.note_statement(SignedFullStatement::sign(
				Statement::Seconded(candidate.clone()),
				&signing_context,
				0,
				&Sr25519Keyring::Alice.pair().into(),
			));

			assert_matches!(noted, NotedStatement::Fresh(_));

			let noted = data.note_statement(SignedFullStatement::sign(
				Statement::Valid(candidate_hash),
				&signing_context,
				1,
				&Sr25519Keyring::Bob.pair().into(),
			));

			assert_matches!(noted, NotedStatement::Fresh(_));

			let noted = data.note_statement(SignedFullStatement::sign(
				Statement::Valid(candidate_hash),
				&signing_context,
				2,
				&Sr25519Keyring::Charlie.pair().into(),
			));

			assert_matches!(noted, NotedStatement::Fresh(_));

			data
		};

		active_heads.insert(hash_c, new_head_data);

		let mut peer_data = PeerData {
			view: old_view,
			view_knowledge: {
				let mut k = HashMap::new();

				k.insert(hash_a, Default::default());
				k.insert(hash_b, Default::default());

				k
			},
		};

		let pool = sp_core::testing::TaskExecutor::new();
		let (mut ctx, mut handle) = polkadot_subsystem::test_helpers::make_subsystem_context(pool);
		let peer = PeerId::random();

		executor::block_on(async move {
			update_peer_view_and_send_unlocked(
				peer.clone(),
				&mut peer_data,
				&mut ctx,
				&active_heads,
				new_view.clone(),
			).await.unwrap();

			assert_eq!(peer_data.view, new_view);
			assert!(!peer_data.view_knowledge.contains_key(&hash_a));
			assert!(peer_data.view_knowledge.contains_key(&hash_b));

			let c_knowledge = peer_data.view_knowledge.get(&hash_c).unwrap();

			assert!(c_knowledge.known_candidates.contains(&candidate_hash));
			assert!(c_knowledge.sent_statements.contains(
				&(CompactStatement::Candidate(candidate_hash), 0)
			));
			assert!(c_knowledge.sent_statements.contains(
				&(CompactStatement::Valid(candidate_hash), 1)
			));
			assert!(c_knowledge.sent_statements.contains(
				&(CompactStatement::Valid(candidate_hash), 2)
			));

			// now see if we got the 3 messages from the active head data.
			let active_head = active_heads.get(&hash_c).unwrap();

			// semi-fragile because hashmap iterator ordering is undefined, but in practice
			// it will not change between runs of the program.
			for statement in active_head.statements_about(candidate_hash) {
				let message = handle.recv().await;
				let expected_to = vec![peer.clone()];
				let expected_protocol = PROTOCOL_V1;
				let expected_payload
					= WireMessage::Statement(hash_c, statement.statement.clone()).encode();

				assert_matches!(
					message,
					AllMessages::NetworkBridge(NetworkBridgeMessage::SendMessage(
						to,
						protocol,
						payload,
					)) => {
						assert_eq!(to, expected_to);
						assert_eq!(protocol, expected_protocol);
						assert_eq!(payload, expected_payload)
					}
				)
			}
		});
	}

	#[test]
	fn circulated_statement_goes_to_all_peers_with_view() {
		let hash_a = [1; 32].into();
		let hash_b = [2; 32].into();
		let hash_c = [3; 32].into();

		let candidate = {
			let mut c = CommittedCandidateReceipt::default();
			c.descriptor.relay_parent = hash_b;
			c.descriptor.para_id = 1.into();
			c
		};

		let peer_a = PeerId::random();
		let peer_b = PeerId::random();
		let peer_c = PeerId::random();

		let peer_a_view = View(vec![hash_a]);
		let peer_b_view = View(vec![hash_a, hash_b]);
		let peer_c_view = View(vec![hash_b, hash_c]);

		let session_index = 1;

		let peer_data_from_view = |view: View| PeerData {
			view: view.clone(),
			view_knowledge: view.0.iter().map(|v| (v.clone(), Default::default())).collect(),
		};

		let mut peer_data: HashMap<_, _> = vec![
			(peer_a.clone(), peer_data_from_view(peer_a_view)),
			(peer_b.clone(), peer_data_from_view(peer_b_view)),
			(peer_c.clone(), peer_data_from_view(peer_c_view)),
		].into_iter().collect();

		let pool = sp_core::testing::TaskExecutor::new();
		let (mut ctx, mut handle) = polkadot_subsystem::test_helpers::make_subsystem_context(pool);

		executor::block_on(async move {
			let statement = {
				let signing_context = SigningContext {
					parent_hash: hash_b,
					session_index,
				};

				let statement = SignedFullStatement::sign(
					Statement::Seconded(candidate),
					&signing_context,
					0,
					&Sr25519Keyring::Alice.pair().into(),
				);

				StoredStatement {
					comparator: StoredStatementComparator {
						compact: statement.payload().to_compact(),
						validator_index: 0,
						signature: statement.signature().clone()
					},
					statement,
				}
			};

			let needs_dependents = circulate_statement(
				&mut peer_data,
				&mut ctx,
				hash_b,
				&statement,
			).await.unwrap();

			{
				assert_eq!(needs_dependents.len(), 2);
				assert!(needs_dependents.contains(&peer_b));
				assert!(needs_dependents.contains(&peer_c));
			}

			let fingerprint = (statement.compact().clone(), 0);

			assert!(
				peer_data.get(&peer_b).unwrap()
				.view_knowledge.get(&hash_b).unwrap()
				.sent_statements.contains(&fingerprint),
			);

			assert!(
				peer_data.get(&peer_c).unwrap()
				.view_knowledge.get(&hash_b).unwrap()
				.sent_statements.contains(&fingerprint),
			);

			let message = handle.recv().await;
			assert_matches!(
				message,
				AllMessages::NetworkBridge(NetworkBridgeMessage::SendMessage(
					to,
					protocol,
					payload,
				)) => {
					assert_eq!(to.len(), 2);
					assert!(to.contains(&peer_b));
					assert!(to.contains(&peer_c));

					assert_eq!(protocol, PROTOCOL_V1);
					assert_eq!(
						payload,
						WireMessage::Statement(hash_b, statement.statement.clone()).encode(),
					);
				}
			)
		});
	}
}