Fix block propagation between non-collator nodes (#363)

* Create builder for test nodes

* Fix syncing issue

* Adds missing file

client/network/tests/sync.rs

@@ -0,0 +1,86 @@
+// Copyright 2021 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate 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.
+
+// Substrate 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+use cumulus_primitives_core::ParaId;
+use cumulus_test_service::{initial_head_data, Keyring::*};
+use futures::join;
+use sc_service::TaskExecutor;
+
+#[substrate_test_utils::test]
+async fn sync_blocks_from_tip_without_being_connected_to_a_collator(task_executor: TaskExecutor) {
+	let mut builder = sc_cli::LoggerBuilder::new("");
+	builder.with_colors(false);
+	let _ = builder.init();
+
+	let para_id = ParaId::from(100);
+
+	// start alice
+	let alice =
+		polkadot_test_service::run_validator_node(task_executor.clone(), Alice, || {}, vec![]);
+
+	// start bob
+	let bob = polkadot_test_service::run_validator_node(
+		task_executor.clone(),
+		Bob,
+		|| {},
+		vec![alice.addr.clone()],
+	);
+
+	// register parachain
+	alice
+		.register_parachain(
+			para_id,
+			cumulus_test_service::runtime::WASM_BINARY
+				.expect("You need to build the WASM binary to run this test!")
+				.to_vec(),
+			initial_head_data(para_id),
+		)
+		.await
+		.unwrap();
+
+	// run charlie as parachain collator
+	let charlie =
+		cumulus_test_service::TestNodeBuilder::new(para_id, task_executor.clone(), Charlie)
+			.enable_collator()
+			.connect_to_relay_chain_nodes(vec![&alice, &bob])
+			.build()
+			.await;
+
+	// run dave as parachain full node
+	let dave = cumulus_test_service::TestNodeBuilder::new(para_id, task_executor.clone(), Dave)
+		.connect_to_parachain_node(&charlie)
+		.connect_to_relay_chain_nodes(vec![&alice, &bob])
+		.build()
+		.await;
+
+	// run eve as parachain full node that is only connected to dave
+	let eve = cumulus_test_service::TestNodeBuilder::new(para_id, task_executor.clone(), Eve)
+		.connect_to_parachain_node(&dave)
+		.exclusively_connect_to_registered_parachain_nodes()
+		.connect_to_relay_chain_nodes(vec![&alice, &bob])
+		.build()
+		.await;
+
+	eve.wait_for_blocks(7).await;
+
+	join!(
+		alice.task_manager.clean_shutdown(),
+		bob.task_manager.clean_shutdown(),
+		charlie.task_manager.clean_shutdown(),
+		dave.task_manager.clean_shutdown(),
+		eve.task_manager.clean_shutdown(),
+	);
+}