lib.rs

					relayers: vec![UnrewardedRelayer {
						relayer: 0,
						messages: DeliveredMessages::new(1),
					}]
					.into_iter()
					.collect(),
				},
			))),
			UnrewardedRelayersState {
				unrewarded_relayer_entries: 1,
				total_messages: 1,
				last_delivered_nonce: 1,
				..Default::default()
			},
		));

		assert_eq!(
			System::<TestRuntime>::events(),
			vec![EventRecord {
				phase: Phase::Initialization,
				event: TestEvent::Messages(Event::MessagesDelivered {
					lane_id: TEST_LANE_ID,
					messages: DeliveredMessages::new(1),
				}),
				topics: vec![],
			}],
		);
	}

	#[test]
	fn pallet_rejects_transactions_if_halted() {
		run_test(|| {
			// send message first to be able to check that delivery_proof fails later
			send_regular_message();

			PalletOperatingMode::<TestRuntime, ()>::put(MessagesOperatingMode::Basic(
				BasicOperatingMode::Halted,
			));

			assert_noop!(
				send_message::<TestRuntime, ()>(
					RuntimeOrigin::signed(1),
					TEST_LANE_ID,
					REGULAR_PAYLOAD,
				),
				Error::<TestRuntime, ()>::NotOperatingNormally,
			);

			assert_noop!(
				Pallet::<TestRuntime>::receive_messages_proof(
					RuntimeOrigin::signed(1),
					TEST_RELAYER_A,
					Ok(vec![message(2, REGULAR_PAYLOAD)]).into(),
					1,
					REGULAR_PAYLOAD.declared_weight,
				),
				Error::<TestRuntime, ()>::BridgeModule(bp_runtime::OwnedBridgeModuleError::Halted),
			);

			assert_noop!(
				Pallet::<TestRuntime>::receive_messages_delivery_proof(
					RuntimeOrigin::signed(1),
					TestMessagesDeliveryProof(Ok((
						TEST_LANE_ID,
						InboundLaneData {
							last_confirmed_nonce: 1,
							relayers: vec![unrewarded_relayer(1, 1, TEST_RELAYER_A)]
								.into_iter()
								.collect(),
						},
					))),
					UnrewardedRelayersState {
						unrewarded_relayer_entries: 1,
						messages_in_oldest_entry: 1,
						total_messages: 1,
						last_delivered_nonce: 1,
					},
				),
				Error::<TestRuntime, ()>::BridgeModule(bp_runtime::OwnedBridgeModuleError::Halted),
			);
		});
	}

	#[test]
	fn pallet_rejects_new_messages_in_rejecting_outbound_messages_operating_mode() {
		run_test(|| {
			// send message first to be able to check that delivery_proof fails later
			send_regular_message();

			PalletOperatingMode::<TestRuntime, ()>::put(
				MessagesOperatingMode::RejectingOutboundMessages,
			);

			assert_noop!(
				send_message::<TestRuntime, ()>(
					RuntimeOrigin::signed(1),
					TEST_LANE_ID,
					REGULAR_PAYLOAD,
				),
				Error::<TestRuntime, ()>::NotOperatingNormally,
			);

			assert_ok!(Pallet::<TestRuntime>::receive_messages_proof(
				RuntimeOrigin::signed(1),
				TEST_RELAYER_A,
				Ok(vec![message(1, REGULAR_PAYLOAD)]).into(),
				1,
				REGULAR_PAYLOAD.declared_weight,
			),);

			assert_ok!(Pallet::<TestRuntime>::receive_messages_delivery_proof(
				RuntimeOrigin::signed(1),
				TestMessagesDeliveryProof(Ok((
					TEST_LANE_ID,
					InboundLaneData {
						last_confirmed_nonce: 1,
						relayers: vec![unrewarded_relayer(1, 1, TEST_RELAYER_A)]
							.into_iter()
							.collect(),
					},
				))),
				UnrewardedRelayersState {
					unrewarded_relayer_entries: 1,
					messages_in_oldest_entry: 1,
					total_messages: 1,
					last_delivered_nonce: 1,
				},
			));
		});
	}

	#[test]
	fn send_message_works() {
		run_test(|| {
			send_regular_message();
		});
	}

	#[test]
	fn send_message_rejects_too_large_message() {
		run_test(|| {
			let mut message_payload = message_payload(1, 0);
			// the payload isn't simply extra, so it'll definitely overflow
			// `MAX_OUTBOUND_PAYLOAD_SIZE` if we add `MAX_OUTBOUND_PAYLOAD_SIZE` bytes to extra
			message_payload
				.extra
				.extend_from_slice(&[0u8; MAX_OUTBOUND_PAYLOAD_SIZE as usize]);
			assert_noop!(
				send_message::<TestRuntime, ()>(
					RuntimeOrigin::signed(1),
					TEST_LANE_ID,
					message_payload.clone(),
				),
				Error::<TestRuntime, ()>::MessageIsTooLarge,
			);

			// let's check that we're able to send `MAX_OUTBOUND_PAYLOAD_SIZE` messages
			while message_payload.encoded_size() as u32 > MAX_OUTBOUND_PAYLOAD_SIZE {
				message_payload.extra.pop();
			}
			assert_eq!(message_payload.encoded_size() as u32, MAX_OUTBOUND_PAYLOAD_SIZE);
			assert_ok!(send_message::<TestRuntime, ()>(
				RuntimeOrigin::signed(1),
				TEST_LANE_ID,
				message_payload,
			),);
		})
	}

	#[test]
	fn chain_verifier_rejects_invalid_message_in_send_message() {
		run_test(|| {
			// messages with this payload are rejected by target chain verifier
			assert_noop!(
				send_message::<TestRuntime, ()>(
					RuntimeOrigin::signed(1),
					TEST_LANE_ID,
					PAYLOAD_REJECTED_BY_TARGET_CHAIN,
				),
				Error::<TestRuntime, ()>::MessageRejectedByChainVerifier(VerificationError::Other(
					mock::TEST_ERROR
				)),
			);
		});
	}

	#[test]
	fn lane_verifier_rejects_invalid_message_in_send_message() {
		run_test(|| {
			// messages with zero fee are rejected by lane verifier
			let mut message = REGULAR_PAYLOAD;
			message.reject_by_lane_verifier = true;
			assert_noop!(
				send_message::<TestRuntime, ()>(RuntimeOrigin::signed(1), TEST_LANE_ID, message,),
				Error::<TestRuntime, ()>::MessageRejectedByLaneVerifier(VerificationError::Other(
					mock::TEST_ERROR
				)),
			);
		});
	}

	#[test]
	fn receive_messages_proof_works() {
		run_test(|| {
			assert_ok!(Pallet::<TestRuntime>::receive_messages_proof(
				RuntimeOrigin::signed(1),
				TEST_RELAYER_A,
				Ok(vec![message(1, REGULAR_PAYLOAD)]).into(),
				1,
				REGULAR_PAYLOAD.declared_weight,
			));

			assert_eq!(InboundLanes::<TestRuntime>::get(TEST_LANE_ID).0.last_delivered_nonce(), 1);

			assert!(TestDeliveryPayments::is_reward_paid(1));
		});
	}

	#[test]
	fn receive_messages_proof_updates_confirmed_message_nonce() {
		run_test(|| {
			// say we have received 10 messages && last confirmed message is 8
			InboundLanes::<TestRuntime, ()>::insert(
				TEST_LANE_ID,
				InboundLaneData {
					last_confirmed_nonce: 8,
					relayers: vec![
						unrewarded_relayer(9, 9, TEST_RELAYER_A),
						unrewarded_relayer(10, 10, TEST_RELAYER_B),
					]
					.into_iter()
					.collect(),
				},
			);
			assert_eq!(
				inbound_unrewarded_relayers_state(TEST_LANE_ID),
				UnrewardedRelayersState {
					unrewarded_relayer_entries: 2,
					messages_in_oldest_entry: 1,
					total_messages: 2,
					last_delivered_nonce: 10,
				},
			);

			// message proof includes outbound lane state with latest confirmed message updated to 9
			let mut message_proof: TestMessagesProof =
				Ok(vec![message(11, REGULAR_PAYLOAD)]).into();
			message_proof.result.as_mut().unwrap()[0].1.lane_state =
				Some(OutboundLaneData { latest_received_nonce: 9, ..Default::default() });

			assert_ok!(Pallet::<TestRuntime>::receive_messages_proof(
				RuntimeOrigin::signed(1),
				TEST_RELAYER_A,
				message_proof,
				1,
				REGULAR_PAYLOAD.declared_weight,
			));

			assert_eq!(
				InboundLanes::<TestRuntime>::get(TEST_LANE_ID).0,
				InboundLaneData {
					last_confirmed_nonce: 9,
					relayers: vec![
						unrewarded_relayer(10, 10, TEST_RELAYER_B),
						unrewarded_relayer(11, 11, TEST_RELAYER_A)
					]
					.into_iter()
					.collect(),
				},
			);
			assert_eq!(
				inbound_unrewarded_relayers_state(TEST_LANE_ID),
				UnrewardedRelayersState {
					unrewarded_relayer_entries: 2,
					messages_in_oldest_entry: 1,
					total_messages: 2,
					last_delivered_nonce: 11,
				},
			);
		});
	}

	#[test]
	fn receive_messages_proof_does_not_accept_message_if_dispatch_weight_is_not_enough() {
		run_test(|| {
			let mut declared_weight = REGULAR_PAYLOAD.declared_weight;
			*declared_weight.ref_time_mut() -= 1;
			assert_noop!(
				Pallet::<TestRuntime>::receive_messages_proof(
					RuntimeOrigin::signed(1),
					TEST_RELAYER_A,
					Ok(vec![message(1, REGULAR_PAYLOAD)]).into(),
					1,
					declared_weight,
				),
				Error::<TestRuntime, ()>::InsufficientDispatchWeight
			);
			assert_eq!(InboundLanes::<TestRuntime>::get(TEST_LANE_ID).last_delivered_nonce(), 0);
		});
	}

	#[test]
	fn receive_messages_proof_rejects_invalid_proof() {
		run_test(|| {
			assert_noop!(
				Pallet::<TestRuntime, ()>::receive_messages_proof(
					RuntimeOrigin::signed(1),
					TEST_RELAYER_A,
					Err(()).into(),
					1,
					Weight::zero(),
				),
				Error::<TestRuntime, ()>::InvalidMessagesProof,
			);
		});
	}

	#[test]
	fn receive_messages_proof_rejects_proof_with_too_many_messages() {
		run_test(|| {
			assert_noop!(
				Pallet::<TestRuntime, ()>::receive_messages_proof(
					RuntimeOrigin::signed(1),
					TEST_RELAYER_A,
					Ok(vec![message(1, REGULAR_PAYLOAD)]).into(),
					u32::MAX,
					Weight::zero(),
				),
				Error::<TestRuntime, ()>::TooManyMessagesInTheProof,
			);
		});
	}

	#[test]
	fn receive_messages_delivery_proof_works() {
		run_test(|| {
			send_regular_message();
			receive_messages_delivery_proof();

			assert_eq!(
				OutboundLanes::<TestRuntime, ()>::get(TEST_LANE_ID).latest_received_nonce,
				1,
			);
		});
	}

	#[test]
	fn receive_messages_delivery_proof_rewards_relayers() {
		run_test(|| {
			assert_ok!(send_message::<TestRuntime, ()>(
				RuntimeOrigin::signed(1),
				TEST_LANE_ID,
				REGULAR_PAYLOAD,
			));
			assert_ok!(send_message::<TestRuntime, ()>(
				RuntimeOrigin::signed(1),
				TEST_LANE_ID,
				REGULAR_PAYLOAD,
			));

			// this reports delivery of message 1 => reward is paid to TEST_RELAYER_A
			let single_message_delivery_proof = TestMessagesDeliveryProof(Ok((
				TEST_LANE_ID,
				InboundLaneData {
					relayers: vec![unrewarded_relayer(1, 1, TEST_RELAYER_A)].into_iter().collect(),
					..Default::default()
				},
			)));
			let single_message_delivery_proof_size = single_message_delivery_proof.size();
			let result = Pallet::<TestRuntime>::receive_messages_delivery_proof(
				RuntimeOrigin::signed(1),
				single_message_delivery_proof,
				UnrewardedRelayersState {
					unrewarded_relayer_entries: 1,
					total_messages: 1,
					last_delivered_nonce: 1,
					..Default::default()
				},
			);
			assert_ok!(result);
			assert_eq!(
				result.unwrap().actual_weight.unwrap(),
				TestWeightInfo::receive_messages_delivery_proof_weight(
					&PreComputedSize(single_message_delivery_proof_size as _),
					&UnrewardedRelayersState {
						unrewarded_relayer_entries: 1,
						total_messages: 1,
						..Default::default()
					},
				)
			);
			assert!(TestDeliveryConfirmationPayments::is_reward_paid(TEST_RELAYER_A, 1));
			assert!(!TestDeliveryConfirmationPayments::is_reward_paid(TEST_RELAYER_B, 1));

			// this reports delivery of both message 1 and message 2 => reward is paid only to
			// TEST_RELAYER_B
			let two_messages_delivery_proof = TestMessagesDeliveryProof(Ok((
				TEST_LANE_ID,
				InboundLaneData {
					relayers: vec![
						unrewarded_relayer(1, 1, TEST_RELAYER_A),
						unrewarded_relayer(2, 2, TEST_RELAYER_B),
					]
					.into_iter()
					.collect(),
					..Default::default()
				},
			)));
			let two_messages_delivery_proof_size = two_messages_delivery_proof.size();
			let result = Pallet::<TestRuntime>::receive_messages_delivery_proof(
				RuntimeOrigin::signed(1),
				two_messages_delivery_proof,
				UnrewardedRelayersState {
					unrewarded_relayer_entries: 2,
					total_messages: 2,
					last_delivered_nonce: 2,
					..Default::default()
				},
			);
			assert_ok!(result);
			// even though the pre-dispatch weight was for two messages, the actual weight is
			// for single message only
			assert_eq!(
				result.unwrap().actual_weight.unwrap(),
				TestWeightInfo::receive_messages_delivery_proof_weight(
					&PreComputedSize(two_messages_delivery_proof_size as _),
					&UnrewardedRelayersState {
						unrewarded_relayer_entries: 1,
						total_messages: 1,
						..Default::default()
					},
				)
			);
			assert!(!TestDeliveryConfirmationPayments::is_reward_paid(TEST_RELAYER_A, 1));
			assert!(TestDeliveryConfirmationPayments::is_reward_paid(TEST_RELAYER_B, 1));
		});
	}

	#[test]
	fn receive_messages_delivery_proof_rejects_invalid_proof() {
		run_test(|| {
			assert_noop!(
				Pallet::<TestRuntime>::receive_messages_delivery_proof(
					RuntimeOrigin::signed(1),
					TestMessagesDeliveryProof(Err(())),
					Default::default(),
				),
				Error::<TestRuntime, ()>::InvalidMessagesDeliveryProof,
			);
		});
	}

	#[test]
	fn receive_messages_delivery_proof_rejects_proof_if_declared_relayers_state_is_invalid() {
		run_test(|| {
			// when number of relayers entries is invalid
			assert_noop!(
				Pallet::<TestRuntime>::receive_messages_delivery_proof(
					RuntimeOrigin::signed(1),
					TestMessagesDeliveryProof(Ok((
						TEST_LANE_ID,
						InboundLaneData {
							relayers: vec![
								unrewarded_relayer(1, 1, TEST_RELAYER_A),
								unrewarded_relayer(2, 2, TEST_RELAYER_B)
							]
							.into_iter()
							.collect(),
							..Default::default()
						}
					))),
					UnrewardedRelayersState {
						unrewarded_relayer_entries: 1,
						total_messages: 2,
						last_delivered_nonce: 2,
						..Default::default()
					},
				),
				Error::<TestRuntime, ()>::InvalidUnrewardedRelayersState,
			);

			// when number of messages is invalid
			assert_noop!(
				Pallet::<TestRuntime>::receive_messages_delivery_proof(
					RuntimeOrigin::signed(1),
					TestMessagesDeliveryProof(Ok((
						TEST_LANE_ID,
						InboundLaneData {
							relayers: vec![
								unrewarded_relayer(1, 1, TEST_RELAYER_A),
								unrewarded_relayer(2, 2, TEST_RELAYER_B)
							]
							.into_iter()
							.collect(),
							..Default::default()
						}
					))),
					UnrewardedRelayersState {
						unrewarded_relayer_entries: 2,
						total_messages: 1,
						last_delivered_nonce: 2,
						..Default::default()
					},
				),
				Error::<TestRuntime, ()>::InvalidUnrewardedRelayersState,
			);

			// when last delivered nonce is invalid
			assert_noop!(
				Pallet::<TestRuntime>::receive_messages_delivery_proof(
					RuntimeOrigin::signed(1),
					TestMessagesDeliveryProof(Ok((
						TEST_LANE_ID,
						InboundLaneData {
							relayers: vec![
								unrewarded_relayer(1, 1, TEST_RELAYER_A),
								unrewarded_relayer(2, 2, TEST_RELAYER_B)
							]
							.into_iter()
							.collect(),
							..Default::default()
						}
					))),
					UnrewardedRelayersState {
						unrewarded_relayer_entries: 2,
						total_messages: 2,
						last_delivered_nonce: 8,
						..Default::default()
					},
				),
				Error::<TestRuntime, ()>::InvalidUnrewardedRelayersState,
			);
		});
	}

	#[test]
	fn receive_messages_accepts_single_message_with_invalid_payload() {
		run_test(|| {
			let mut invalid_message = message(1, REGULAR_PAYLOAD);
			invalid_message.payload = Vec::new();

			assert_ok!(Pallet::<TestRuntime, ()>::receive_messages_proof(
				RuntimeOrigin::signed(1),
				TEST_RELAYER_A,
				Ok(vec![invalid_message]).into(),
				1,
				Weight::zero(), /* weight may be zero in this case (all messages are
				                 * improperly encoded) */
			),);

			assert_eq!(InboundLanes::<TestRuntime>::get(TEST_LANE_ID).last_delivered_nonce(), 1,);
		});
	}

	#[test]
	fn receive_messages_accepts_batch_with_message_with_invalid_payload() {
		run_test(|| {
			let mut invalid_message = message(2, REGULAR_PAYLOAD);
			invalid_message.payload = Vec::new();

			assert_ok!(Pallet::<TestRuntime, ()>::receive_messages_proof(
				RuntimeOrigin::signed(1),
				TEST_RELAYER_A,
				Ok(
					vec![message(1, REGULAR_PAYLOAD), invalid_message, message(3, REGULAR_PAYLOAD),]
				)
				.into(),
				3,
				REGULAR_PAYLOAD.declared_weight + REGULAR_PAYLOAD.declared_weight,
			),);

			assert_eq!(InboundLanes::<TestRuntime>::get(TEST_LANE_ID).last_delivered_nonce(), 3,);
		});
	}

	#[test]
	fn actual_dispatch_weight_does_not_overlow() {
		run_test(|| {
			let message1 = message(1, message_payload(0, u64::MAX / 2));
			let message2 = message(2, message_payload(0, u64::MAX / 2));
			let message3 = message(3, message_payload(0, u64::MAX / 2));

			assert_noop!(
				Pallet::<TestRuntime, ()>::receive_messages_proof(
					RuntimeOrigin::signed(1),
					TEST_RELAYER_A,
					// this may cause overflow if source chain storage is invalid
					Ok(vec![message1, message2, message3]).into(),
					3,
					Weight::MAX,
				),
				Error::<TestRuntime, ()>::InsufficientDispatchWeight
			);
			assert_eq!(InboundLanes::<TestRuntime>::get(TEST_LANE_ID).last_delivered_nonce(), 0);
		});
	}

	#[test]
	fn ref_time_refund_from_receive_messages_proof_works() {
		run_test(|| {
			fn submit_with_unspent_weight(
				nonce: MessageNonce,
				unspent_weight: u64,
			) -> (Weight, Weight) {
				let mut payload = REGULAR_PAYLOAD;
				*payload.dispatch_result.unspent_weight.ref_time_mut() = unspent_weight;
				let proof = Ok(vec![message(nonce, payload)]).into();
				let messages_count = 1;
				let pre_dispatch_weight =
					<TestRuntime as Config>::WeightInfo::receive_messages_proof_weight(
						&proof,
						messages_count,
						REGULAR_PAYLOAD.declared_weight,
					);
				let result = Pallet::<TestRuntime>::receive_messages_proof(
					RuntimeOrigin::signed(1),
					TEST_RELAYER_A,
					proof,
					messages_count,
					REGULAR_PAYLOAD.declared_weight,
				)
				.expect("delivery has failed");
				let post_dispatch_weight =
					result.actual_weight.expect("receive_messages_proof always returns Some");

				// message delivery transactions are never free
				assert_eq!(result.pays_fee, Pays::Yes);

				(pre_dispatch_weight, post_dispatch_weight)
			}

			// when dispatch is returning `unspent_weight < declared_weight`
			let (pre, post) = submit_with_unspent_weight(1, 1);
			assert_eq!(post.ref_time(), pre.ref_time() - 1);

			// when dispatch is returning `unspent_weight = declared_weight`
			let (pre, post) =
				submit_with_unspent_weight(2, REGULAR_PAYLOAD.declared_weight.ref_time());
			assert_eq!(
				post.ref_time(),
				pre.ref_time() - REGULAR_PAYLOAD.declared_weight.ref_time()
			);

			// when dispatch is returning `unspent_weight > declared_weight`
			let (pre, post) =
				submit_with_unspent_weight(3, REGULAR_PAYLOAD.declared_weight.ref_time() + 1);
			assert_eq!(
				post.ref_time(),
				pre.ref_time() - REGULAR_PAYLOAD.declared_weight.ref_time()
			);

			// when there's no unspent weight
			let (pre, post) = submit_with_unspent_weight(4, 0);
			assert_eq!(post.ref_time(), pre.ref_time());

			// when dispatch is returning `unspent_weight < declared_weight`
			let (pre, post) = submit_with_unspent_weight(5, 1);
			assert_eq!(post.ref_time(), pre.ref_time() - 1);
		});
	}

	#[test]
	fn proof_size_refund_from_receive_messages_proof_works() {
		run_test(|| {
			let max_entries = crate::mock::MaxUnrewardedRelayerEntriesAtInboundLane::get() as usize;

			// if there's maximal number of unrewarded relayer entries at the inbound lane, then
			// `proof_size` is unchanged in post-dispatch weight
			let proof: TestMessagesProof = Ok(vec![message(101, REGULAR_PAYLOAD)]).into();
			let messages_count = 1;
			let pre_dispatch_weight =
				<TestRuntime as Config>::WeightInfo::receive_messages_proof_weight(
					&proof,
					messages_count,
					REGULAR_PAYLOAD.declared_weight,
				);
			InboundLanes::<TestRuntime>::insert(
				TEST_LANE_ID,
				StoredInboundLaneData(InboundLaneData {
					relayers: vec![
						UnrewardedRelayer {
							relayer: 42,
							messages: DeliveredMessages { begin: 0, end: 100 }
						};
						max_entries
					]
					.into_iter()
					.collect(),
					last_confirmed_nonce: 0,
				}),
			);
			let post_dispatch_weight = Pallet::<TestRuntime>::receive_messages_proof(
				RuntimeOrigin::signed(1),
				TEST_RELAYER_A,
				proof.clone(),
				messages_count,
				REGULAR_PAYLOAD.declared_weight,
			)
			.unwrap()
			.actual_weight
			.unwrap();
			assert_eq!(post_dispatch_weight.proof_size(), pre_dispatch_weight.proof_size());

			// if count of unrewarded relayer entries is less than maximal, then some `proof_size`
			// must be refunded
			InboundLanes::<TestRuntime>::insert(
				TEST_LANE_ID,
				StoredInboundLaneData(InboundLaneData {
					relayers: vec![
						UnrewardedRelayer {
							relayer: 42,
							messages: DeliveredMessages { begin: 0, end: 100 }
						};
						max_entries - 1
					]
					.into_iter()
					.collect(),
					last_confirmed_nonce: 0,
				}),
			);
			let post_dispatch_weight = Pallet::<TestRuntime>::receive_messages_proof(
				RuntimeOrigin::signed(1),
				TEST_RELAYER_A,
				proof,
				messages_count,
				REGULAR_PAYLOAD.declared_weight,
			)
			.unwrap()
			.actual_weight
			.unwrap();
			assert!(
				post_dispatch_weight.proof_size() < pre_dispatch_weight.proof_size(),
				"Expected post-dispatch PoV {} to be less than pre-dispatch PoV {}",
				post_dispatch_weight.proof_size(),
				pre_dispatch_weight.proof_size(),
			);
		});
	}

	#[test]
	fn messages_delivered_callbacks_are_called() {
		run_test(|| {
			send_regular_message();
			send_regular_message();
			send_regular_message();

			// messages 1+2 are confirmed in 1 tx, message 3 in a separate tx
			// dispatch of message 2 has failed
			let mut delivered_messages_1_and_2 = DeliveredMessages::new(1);
			delivered_messages_1_and_2.note_dispatched_message();
			let messages_1_and_2_proof = Ok((
				TEST_LANE_ID,
				InboundLaneData {
					last_confirmed_nonce: 0,
					relayers: vec![UnrewardedRelayer {
						relayer: 0,
						messages: delivered_messages_1_and_2.clone(),
					}]
					.into_iter()
					.collect(),
				},
			));
			let delivered_message_3 = DeliveredMessages::new(3);
			let messages_3_proof = Ok((
				TEST_LANE_ID,
				InboundLaneData {
					last_confirmed_nonce: 0,
					relayers: vec![UnrewardedRelayer { relayer: 0, messages: delivered_message_3 }]
						.into_iter()
						.collect(),
				},
			));

			// first tx with messages 1+2
			assert_ok!(Pallet::<TestRuntime>::receive_messages_delivery_proof(
				RuntimeOrigin::signed(1),
				TestMessagesDeliveryProof(messages_1_and_2_proof),
				UnrewardedRelayersState {
					unrewarded_relayer_entries: 1,
					total_messages: 2,
					last_delivered_nonce: 2,
					..Default::default()
				},
			));
			// second tx with message 3
			assert_ok!(Pallet::<TestRuntime>::receive_messages_delivery_proof(
				RuntimeOrigin::signed(1),
				TestMessagesDeliveryProof(messages_3_proof),
				UnrewardedRelayersState {
					unrewarded_relayer_entries: 1,
					total_messages: 1,
					last_delivered_nonce: 3,
					..Default::default()
				},
			));
		});
	}

	#[test]
	fn receive_messages_delivery_proof_rejects_proof_if_trying_to_confirm_more_messages_than_expected(
	) {
		run_test(|| {
			// send message first to be able to check that delivery_proof fails later
			send_regular_message();

			// 1) InboundLaneData declares that the `last_confirmed_nonce` is 1;
			// 2) InboundLaneData has no entries => `InboundLaneData::last_delivered_nonce()`
			//    returns `last_confirmed_nonce`;
			// 3) it means that we're going to confirm delivery of messages 1..=1;
			// 4) so the number of declared messages (see `UnrewardedRelayersState`) is `0` and
			//    numer of actually confirmed messages is `1`.
			assert_noop!(
				Pallet::<TestRuntime>::receive_messages_delivery_proof(
					RuntimeOrigin::signed(1),
					TestMessagesDeliveryProof(Ok((
						TEST_LANE_ID,
						InboundLaneData { last_confirmed_nonce: 1, relayers: Default::default() },
					))),
					UnrewardedRelayersState { last_delivered_nonce: 1, ..Default::default() },
				),
				Error::<TestRuntime, ()>::TryingToConfirmMoreMessagesThanExpected,
			);
		});
	}

	#[test]
	fn storage_keys_computed_properly() {
		assert_eq!(
			PalletOperatingMode::<TestRuntime>::storage_value_final_key().to_vec(),
			bp_messages::storage_keys::operating_mode_key("Messages").0,
		);

		assert_eq!(
			OutboundMessages::<TestRuntime>::storage_map_final_key(MessageKey {
				lane_id: TEST_LANE_ID,
				nonce: 42
			}),
			bp_messages::storage_keys::message_key("Messages", &TEST_LANE_ID, 42).0,
		);

		assert_eq!(
			OutboundLanes::<TestRuntime>::storage_map_final_key(TEST_LANE_ID),
			bp_messages::storage_keys::outbound_lane_data_key("Messages", &TEST_LANE_ID).0,
		);

		assert_eq!(
			InboundLanes::<TestRuntime>::storage_map_final_key(TEST_LANE_ID),
			bp_messages::storage_keys::inbound_lane_data_key("Messages", &TEST_LANE_ID).0,
		);
	}

	#[test]
	fn inbound_message_details_works() {
		run_test(|| {
			assert_eq!(
				Pallet::<TestRuntime>::inbound_message_data(
					TEST_LANE_ID,
					REGULAR_PAYLOAD.encode(),
					OutboundMessageDetails { nonce: 0, dispatch_weight: Weight::zero(), size: 0 },
				),
				InboundMessageDetails { dispatch_weight: REGULAR_PAYLOAD.declared_weight },
			);
		});
	}

	#[test]
	fn on_idle_callback_respects_remaining_weight() {
		run_test(|| {
			send_regular_message();
			send_regular_message();
			send_regular_message();
			send_regular_message();

			assert_ok!(Pallet::<TestRuntime>::receive_messages_delivery_proof(
				RuntimeOrigin::signed(1),
				TestMessagesDeliveryProof(Ok((
					TEST_LANE_ID,
					InboundLaneData {
						last_confirmed_nonce: 4,
						relayers: vec![unrewarded_relayer(1, 4, TEST_RELAYER_A)]
							.into_iter()
							.collect(),
					},
				))),
				UnrewardedRelayersState {
					unrewarded_relayer_entries: 1,
					messages_in_oldest_entry: 4,
					total_messages: 4,
					last_delivered_nonce: 4,
				},
			));

			// all 4 messages may be pruned now
			assert_eq!(
				outbound_lane::<TestRuntime, ()>(TEST_LANE_ID).data().latest_received_nonce,
				4
			);
			assert_eq!(
				outbound_lane::<TestRuntime, ()>(TEST_LANE_ID).data().oldest_unpruned_nonce,
				1
			);
			System::<TestRuntime>::set_block_number(2);

			// if passed wight is too low to do anything
			let dbw = DbWeight::get();
			assert_eq!(
				Pallet::<TestRuntime, ()>::on_idle(0, dbw.reads_writes(1, 1)),
				Weight::zero(),
			);
			assert_eq!(
				outbound_lane::<TestRuntime, ()>(TEST_LANE_ID).data().oldest_unpruned_nonce,
				1
			);

			// if passed wight is enough to prune single message
			assert_eq!(
				Pallet::<TestRuntime, ()>::on_idle(0, dbw.reads_writes(1, 2)),
				dbw.reads_writes(1, 2),
			);
			assert_eq!(
				outbound_lane::<TestRuntime, ()>(TEST_LANE_ID).data().oldest_unpruned_nonce,
				2
			);

			// if passed wight is enough to prune two more messages
			assert_eq!(
				Pallet::<TestRuntime, ()>::on_idle(0, dbw.reads_writes(1, 3)),
				dbw.reads_writes(1, 3),
			);
			assert_eq!(
				outbound_lane::<TestRuntime, ()>(TEST_LANE_ID).data().oldest_unpruned_nonce,
				4
			);

			// if passed wight is enough to prune many messages
			assert_eq!(
				Pallet::<TestRuntime, ()>::on_idle(0, dbw.reads_writes(100, 100)),
				dbw.reads_writes(1, 2),
			);
			assert_eq!(
				outbound_lane::<TestRuntime, ()>(TEST_LANE_ID).data().oldest_unpruned_nonce,
				5
			);
		});
	}

	#[test]
	fn on_idle_callback_is_rotating_lanes_to_prune() {
		run_test(|| {
			// send + receive confirmation for lane 1
			send_regular_message();
			receive_messages_delivery_proof();
			// send + receive confirmation for lane 2
			assert_ok!(send_message::<TestRuntime, ()>(
				RuntimeOrigin::signed(1),
				TEST_LANE_ID_2,
				REGULAR_PAYLOAD,
			));
			assert_ok!(Pallet::<TestRuntime>::receive_messages_delivery_proof(
				RuntimeOrigin::signed(1),
				TestMessagesDeliveryProof(Ok((
					TEST_LANE_ID_2,
					InboundLaneData {
						last_confirmed_nonce: 1,
						relayers: vec![unrewarded_relayer(1, 1, TEST_RELAYER_A)]
							.into_iter()
							.collect(),
					},
				))),
				UnrewardedRelayersState {
					unrewarded_relayer_entries: 1,
					messages_in_oldest_entry: 1,
					total_messages: 1,
					last_delivered_nonce: 1,
				},
			));

			// nothing is pruned yet
			assert_eq!(
				outbound_lane::<TestRuntime, ()>(TEST_LANE_ID).data().latest_received_nonce,
				1
			);
			assert_eq!(
				outbound_lane::<TestRuntime, ()>(TEST_LANE_ID).data().oldest_unpruned_nonce,
				1
			);
			assert_eq!(
				outbound_lane::<TestRuntime, ()>(TEST_LANE_ID_2).data().latest_received_nonce,
				1
			);
			assert_eq!(
				outbound_lane::<TestRuntime, ()>(TEST_LANE_ID_2).data().oldest_unpruned_nonce,
				1
			);

			// in block#2.on_idle lane messages of lane 1 are pruned
			let dbw = DbWeight::get();
			System::<TestRuntime>::set_block_number(2);
			assert_eq!(
				Pallet::<TestRuntime, ()>::on_idle(0, dbw.reads_writes(100, 100)),