use own timeout in tests instead of smol-timeout (#1618)

polkadot/node/subsystem-test-helpers/src/lib.rs

@@ -24,6 +24,7 @@ use futures::poll;
 use futures::prelude::*;
 use futures_timer::Delay;
 use parking_lot::Mutex;
+use pin_project::pin_project;
 use sp_core::{testing::TaskExecutor, traits::SpawnNamed};
 
 use std::convert::Infallible;
@@ -286,3 +287,45 @@ pub fn subsystem_test_harness<M, OverseerFactory, Overseer, TestFactory, Test>(
 		}
 	});
 }
+
+/// A future that wraps another future with a `Delay` allowing for time-limited futures.
+#[pin_project]
+pub struct Timeout<F: Future> {
+	#[pin]
+	future: F,
+	#[pin]
+	delay: Delay,
+}
+
+/// Extends `Future` to allow time-limited futures.
+pub trait TimeoutExt: Future {
+	fn timeout(self, duration: Duration) -> Timeout<Self>
+	where
+		Self: Sized,
+	{
+		Timeout {
+			future: self,
+			delay: Delay::new(duration),
+		}
+	}
+}
+
+impl<F: Future> TimeoutExt for F {}
+
+impl<F: Future> Future for Timeout<F> {
+	type Output = Option<F::Output>;
+
+	fn poll(self: Pin<&mut Self>, ctx: &mut Context) -> Poll<Self::Output> {
+		let this = self.project();
+
+		if this.delay.poll(ctx).is_ready() {
+			return Poll::Ready(None);
+		}
+
+		if let Poll::Ready(output) = this.future.poll(ctx) {
+			return Poll::Ready(Some(output));
+		}
+
+		Poll::Pending
+	}
+}