Fix spurrious test failure (#288)

There was a race condition in the test where the server connection
sometimes closed before the final client opereation. This triggered an
unwrap in the test.

This patch updates the test to ensuree that the mock server connection
stays open until the client test is complete.

tests/h2-tests/tests/client_request.rs

@@ -850,8 +850,9 @@ fn notify_on_send_capacity() {
     use std::sync::mpsc;
 
     let _ = ::env_logger::try_init();
+
     let (io, srv) = mock::new();
-    let (done_tx, done_rx) = mpsc::channel();
+    let (done_tx, done_rx) = futures::sync::oneshot::channel();
     let (tx, rx) = mpsc::channel();
 
     let mut settings = frame::Settings::default();
@@ -884,6 +885,9 @@ fn notify_on_send_capacity() {
                 .eos(),
         )
         .send_frame(frames::headers(5).response(200).eos())
+        // Don't close the connection until the client is done doing its
+        // checks.
+        .wait_for(done_rx)
         .close()
         ;
 
@@ -922,10 +926,11 @@ fn notify_on_send_capacity() {
             });
 
             conn.expect("h2")
-        });
+        })
+        .expect("client");
+
 
     client.join(srv).wait().unwrap();
-    done_rx.recv().unwrap();
 }
 
 #[test]