fix: execute-block handle no explicit --at (#84)

`execute-block` currently panics during block execution if `--at` is not
passed, due to trying to execute a block that doesn't match current
state.

Cargo.toml

@@ -4,7 +4,7 @@ resolver = "2"
 members = ["cli", "core"]
 
 [workspace.package]
-version = "0.6.1"
+version = "0.6.2"
 authors = ["Parity Technologies <[email protected]>"]
 description = "Substrate's programmatic testing framework."
 edition = "2021"

core/src/commands/execute_block.rs

@@ -98,7 +98,27 @@ where
     let rpc = ws_client(&block_ws_uri).await?;
 
     let live_state = match command.state {
-        State::Live(live_state) => live_state,
+        State::Live(live_state) => {
+            // If no --at is provided, get the latest block to replay
+            if live_state.at.is_some() {
+                live_state
+            } else {
+                let header =
+                    ChainApi::<(), Block::Hash, Block::Header, SignedBlock<Block>>::header(
+                        &rpc, None,
+                    )
+                    .await
+                    .map_err(rpc_err_handler)?
+                    .expect("header exists, block should also exist; qed");
+                LiveState {
+                    uri: block_ws_uri,
+                    at: Some(hex::encode(header.hash().encode())),
+                    pallet: Default::default(),
+                    hashed_prefixes: Default::default(),
+                    child_tree: Default::default(),
+                }
+            }
+        }
         _ => {
             unreachable!("execute block currently only supports Live state")
         }

core/tests/execute_block.rs

@@ -28,7 +28,6 @@ use tokio::process::Command;
 #[tokio::test]
 async fn execute_block_works() {
     let port = 45789;
-    let ws_url = format!("ws://localhost:{}", port);
 
     // Spawn a dev node.
     let _ = std::thread::spawn(move || {
@@ -46,7 +45,10 @@ async fn execute_block_works() {
     // Wait some time to ensure the node is warmed up.
     std::thread::sleep(Duration::from_secs(90));
 
+    // Test passing --at
     common::run_with_timeout(Duration::from_secs(60), async move {
+        let ws_url = format!("ws://localhost:{}", port);
+
         fn execute_block(ws_url: &str, at: Hash) -> tokio::process::Child {
             Command::new(cargo_bin("try-runtime"))
                 .stdout(std::process::Stdio::piped())
@@ -83,5 +85,41 @@ async fn execute_block_works() {
             .status
             .success());
     })
+    .await;
+
+    // Test not passing --at
+    common::run_with_timeout(Duration::from_secs(60), async move {
+        let ws_url = format!("ws://localhost:{}", port);
+
+        fn execute_block(ws_url: &str) -> tokio::process::Child {
+            Command::new(cargo_bin("try-runtime"))
+                .stdout(std::process::Stdio::piped())
+                .stderr(std::process::Stdio::piped())
+                .arg("--runtime=existing")
+                .args(["execute-block"])
+                .args(["live", format!("--uri={}", ws_url).as_str()])
+                .kill_on_drop(true)
+                .spawn()
+                .unwrap()
+        }
+
+        // Try to execute the block.
+        let mut block_execution = execute_block(&ws_url);
+        let expected_output = r".*Block #(\d+) successfully executed";
+        let re = Regex::new(expected_output).unwrap();
+        let matched =
+            common::wait_for_stream_pattern_match(block_execution.stderr.take().unwrap(), re).await;
+
+        // Assert that the block-execution process has executed a block.
+        assert!(matched.is_ok());
+
+        // Assert that the block-execution exited succesfully
+        assert!(block_execution
+            .wait_with_output()
+            .await
+            .unwrap()
+            .status
+            .success());
+    })
     .await
 }