test that fast forward runs and logs expected output

utils/frame/try-runtime/cli/tests/fast_forward.rs

@@ -0,0 +1,74 @@
+// This file is part of Substrate.
+
+// Copyright (C) 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/>.
+
+#![cfg(unix)]
+
+#[cfg(feature = "try-runtime")]
+mod tests {
+	use assert_cmd::cargo::cargo_bin;
+	use regex::Regex;
+	use std::{
+		process::{self},
+		str::from_utf8,
+		time::Duration,
+	};
+	use substrate_cli_test_utils as common;
+	use tokio::process::Command;
+
+	#[tokio::test]
+	async fn follow_chain_works() {
+		// Build substrate so binaries used in the test use the latest code.
+		common::build_substrate(&["--features=try-runtime"]);
+
+		let n_blocks = 10;
+		common::run_with_timeout(Duration::from_secs(60), async move {
+			let run_fast_forward = |ws_url: String| async move {
+				Command::new(cargo_bin("substrate"))
+					.stdout(process::Stdio::piped())
+					.stderr(process::Stdio::piped())
+					.args(&["try-runtime", "--runtime=existing"])
+					.args(&[
+						"fast-forward",
+						format!("--n-blocks={}", n_blocks).as_str(),
+						"live",
+						format!("--uri={}", ws_url).as_str(),
+					])
+					.kill_on_drop(true)
+					.output()
+					.await
+					.unwrap()
+			};
+
+			// Start a node and wait for it to begin finalizing blocks
+			let mut node = common::KillChildOnDrop(common::start_node());
+			let ws_url = common::extract_info_from_output(node.stderr.take().unwrap()).0.ws_url;
+			common::wait_n_finalized_blocks(1, &ws_url).await;
+
+			// Make sure fast_forward logged "Executed the new block" the expected number of times
+			// and exited successfully
+			let fast_forward = run_fast_forward(ws_url).await;
+			let re = Regex::new(
+				format!(r#"(?:(?s).*Executed the new block.*\s*){}"#, n_blocks).as_str(),
+			)
+			.unwrap();
+			assert!(re.is_match(from_utf8(&fast_forward.stderr).unwrap()));
+			assert!(fast_forward.status.success());
+		})
+		.await;
+	}
+}