Switch RPCs to stable futures (#3287)

substrate/core/rpc/src/system/tests.rs

@@ -20,7 +20,7 @@ use network::{self, PeerId};
 use network::config::Roles;
 use test_client::runtime::Block;
 use assert_matches::assert_matches;
-use futures::{prelude::*, sync::mpsc};
+use futures03::{prelude::*, channel::mpsc};
 use std::thread;
 
 struct Status {
@@ -46,7 +46,7 @@ fn api<T: Into<Option<Status>>>(sync: T) -> System<Block> {
 	let should_have_peers = !status.is_dev;
 	let (tx, rx) = mpsc::unbounded();
 	thread::spawn(move || {
-		tokio::run(rx.for_each(move |request| {
+		futures03::executor::block_on(rx.for_each(move |request| {
 			match request {
 				Request::Health(sender) => {
 					let _ = sender.send(Health {
@@ -82,7 +82,7 @@ fn api<T: Into<Option<Status>>>(sync: T) -> System<Block> {
 				}
 			};
 
-			Ok(())
+			future::ready(())
 		}))
 	});
 	System::new(SystemInfo {