Provides AsyncWrite with flush

As per Tokio and others, this commit provides a `poll_flush` method on `AsyncWrite` so that a best-effort attempt at wakening once all bytes are flushed can be made.

1 files changed, 7 insertions, 0 deletions

diff --git a/embassy-hal-common/src/ring_buffer.rs b/embassy-hal-common/src/ring_buffer.rs
index 6829f62f5..fcad68bb1 100644
--- a/embassy-hal-common/src/ring_buffer.rs
+++ b/embassy-hal-common/src/ring_buffer.rs
@@ -125,5 +125,12 @@ mod tests {
         let buf = rb.pop_buf();
         assert_eq!(1, buf.len());
         assert_eq!(4, buf[0]);
+        rb.pop(1);
+
+        let buf = rb.pop_buf();
+        assert_eq!(0, buf.len());
+
+        let buf = rb.push_buf();
+        assert_eq!(4, buf.len());
     }
 }