Translate types and utilities tests

tests/compat/src/lib.rs

@@ -1,11 +1,34 @@
 //! Shared deterministic fixtures used by translated compatibility tests.
 
 use std::collections::BTreeMap;
+use std::future::Future;
 use std::io;
 use std::path::{Component, Path, PathBuf};
 use std::sync::{Arc, Mutex};
+use std::task::{Context, Poll, Wake, Waker};
 use std::time::Duration;
 
+/// Runs one test future without choosing an async runtime for the library.
+pub fn block_on<F: Future>(future: F) -> F::Output {
+    struct ThreadWake(std::thread::Thread);
+
+    impl Wake for ThreadWake {
+        fn wake(self: Arc<Self>) {
+            self.0.unpark();
+        }
+    }
+
+    let waker = Waker::from(Arc::new(ThreadWake(std::thread::current())));
+    let mut context = Context::from_waker(&waker);
+    let mut future = std::pin::pin!(future);
+    loop {
+        match future.as_mut().poll(&mut context) {
+            Poll::Ready(output) => return output,
+            Poll::Pending => std::thread::park(),
+        }
+    }
+}
+
 /// Asserts equality within the exact absolute tolerance carried by an upstream test.
 ///
 /// # Panics
@@ -231,6 +254,7 @@ mod tests {
 
     #[test]
     fn deterministic_harness_covers_clock_network_and_bytes() {
+        assert_eq!(block_on(std::future::ready(7)), 7);
         assert_close(1.001, 1.0, 0.01);
         assert_bytes_eq(&decode_hex("00 ff 2A").unwrap(), &[0, 255, 42]);
         assert!(decode_hex("é").is_err());