substrate runner: increase line read + dump CLI output if parsing fails (#1781)

* substrate runner: dump CLI output parsing fails

* cargo fmt

* Update testing/substrate-runner/src/lib.rs

* fix grumbles

* disable flaky test

* ignore reconn test too

* ignore more tests

* fix tests

* improve log parsing

* Update testing/integration-tests/src/full_client/client/unstable_rpcs.rs

* Update testing/integration-tests/src/full_client/client/unstable_rpcs.rs

* fix nits

* fix reconn test

testing/integration-tests/src/utils/wait_for_blocks.rs

@@ -2,7 +2,10 @@
 // This file is dual-licensed as Apache-2.0 or GPL-3.0.
 // see LICENSE for license details.
 
-use subxt::{client::OnlineClientT, Config};
+use subxt::{
+    backend::StreamOf, blocks::Block, client::OnlineClientT, Config, Error, OnlineClient,
+    SubstrateConfig,
+};
 
 /// Wait for blocks to be produced before running tests. Specifically, we
 /// wait for one more finalized block to be produced, which is important because
@@ -23,3 +26,25 @@ pub async fn wait_for_number_of_blocks<C: Config>(
         sub.next().await;
     }
 }
+
+/// Consumes the initial blocks from the stream of blocks to ensure that the stream is up-to-date.
+///
+/// This may be useful on the unstable backend when the initial blocks may be large
+/// and one relies on something to included in finalized block in ner future.
+pub async fn consume_initial_blocks(
+    blocks: &mut StreamOf<Result<Block<SubstrateConfig, OnlineClient<SubstrateConfig>>, Error>>,
+) {
+    use tokio::time::{interval_at, Duration, Instant};
+    const MAX_DURATION: Duration = Duration::from_millis(200);
+
+    let mut now = interval_at(Instant::now() + MAX_DURATION, MAX_DURATION);
+
+    loop {
+        tokio::select! {
+            _ = now.tick() => {
+                break;
+            }
+            _  = blocks.next() => {}
+        }
+    }
+}