zebrad tests: try waiting for RPC port to accept connections in zebra_rpc_conflict to reduce flakiness

Author: dmidem

zebrad/tests/acceptance.rs

@@ -2230,6 +2230,20 @@ fn zebra_tracing_conflict() -> Result<()> {
     Ok(())
 }
 
+fn wait_until_listening(addr: std::net::SocketAddr, timeout: std::time::Duration) -> bool {
+    use std::net::TcpStream;
+    use std::time::{Duration, Instant};
+
+    let start = Instant::now();
+    while start.elapsed() < timeout {
+        if TcpStream::connect_timeout(&addr, Duration::from_millis(150)).is_ok() {
+            return true;
+        }
+        std::thread::sleep(Duration::from_millis(50));
+    }
+    false
+}
+
 /// Start 2 zebrad nodes using the same RPC listener port, but different
 /// state directories and Zcash listener ports. The first node should get
 /// exclusive use of the port. The second node will panic.
@@ -2250,18 +2264,28 @@ fn zebra_rpc_conflict() -> Result<()> {
     //
     // This is the required setting to detect port conflicts.
     let mut config = random_known_rpc_port_config(false, &Mainnet)?;
+    let listen_addr = config
+        .rpc
+        .listen_addr
+        .expect("random_known_rpc_port_config must set rpc.listen_addr");
 
     let dir1 = testdir()?.with_config(&mut config)?;
-    let regex1 = regex::escape(&format!(
-        r"Opened RPC endpoint at {}",
-        config.rpc.listen_addr.unwrap(),
-    ));
+    let regex1 = regex::escape(&format!(r"Opened RPC endpoint at {}", listen_addr,));
+
+    use std::time::Duration;
+
+    const RPC_READY_TIMEOUT: Duration = Duration::from_secs(5);
+    assert!(
+        wait_until_listening(listen_addr, RPC_READY_TIMEOUT),
+        "RPC endpoint did not become connectable at {} within {:?}",
+        listen_addr,
+        RPC_READY_TIMEOUT
+    );
 
     // From another folder create a configuration with the same endpoint.
     // `rpc.listen_addr` will be the same in the 2 nodes.
     // But they will have different Zcash listeners (auto port) and states (ephemeral)
     let dir2 = testdir()?.with_config(&mut config)?;
-
     check_config_conflict(dir1, regex1.as_str(), dir2, "Address already in use")?;
 
     Ok(())