StreamRef sends RST_STREAM on drop (#109)

This PR modifies the `Drop` implementation for `StreamRef` to reset the underlying stream if it is the last reference to that stream. Since both `Stream` and `Body` are internally just a `StreamRef`, this means they will both reset the stream on drop; thus, this closes #100.

The assertion that the store no longer contains the dropped stream ID at the end of the `Drop` method  had to be removed, as the stream has to be reset from inside of a `transition` block (which now manages releasing that ID for us), and the `transition` closure moves the value of `stream`, making the assertion no longer possible.

Modifications to some of the tests in `flow_control.rs` were also necessary, in order to prevent `StreamRef`s from being dropped too early.

tests/flow_control.rs

@@ -378,9 +378,12 @@ fn stream_close_by_data_frame_releases_capacity() {
         // Send the frame
         s2.send_data("hello".into(), true).unwrap();
 
-        // Wait for the connection to close
-        h2.unwrap()
-    });
+        // Drive both streams to prevent the handles from being dropped
+        // (which will send a RST_STREAM) before the connection is closed.
+        h2.drive(s1)
+          .and_then(move |(h2, _)| h2.drive(s2))
+    })
+    .unwrap();
 
     let srv = srv.assert_client_handshake()
         .unwrap()
@@ -446,9 +449,12 @@ fn stream_close_by_trailers_frame_releases_capacity() {
         // Send the frame
         s2.send_data("hello".into(), true).unwrap();
 
-        // Wait for the connection to close
-        h2.unwrap()
-    });
+        // Drive both streams to prevent the handles from being dropped
+        // (which will send a RST_STREAM) before the connection is closed.
+        h2.drive(s1)
+          .and_then(move |(h2, _)| h2.drive(s2))
+    })
+    .unwrap();
 
     let srv = srv.assert_client_handshake().unwrap()
         // Get the first frame
@@ -527,7 +533,16 @@ fn recv_window_update_on_stream_closed_by_data_frame() {
             stream.send_data("hello".into(), true).unwrap();
 
             // Wait for the connection to close
-            h2.unwrap()
+            h2.map(|h2| {
+                // keep `stream` from being dropped in order to prevent
+                // it from sending an RST_STREAM frame.
+                std::mem::forget(stream);
+                // i know this is kind of evil, but it's necessary to
+                // ensure that the stream is closed by the EOS frame,
+                // and not by the RST_STREAM.
+                h2
+            })
+                .unwrap()
         });
 
     let srv = srv.assert_client_handshake()

tests/prioritization.rs

@@ -202,7 +202,12 @@ fn send_data_receive_window_update() {
             let payload = vec![0; frame::DEFAULT_INITIAL_WINDOW_SIZE as usize];
             stream.send_data(payload.into(), true).unwrap();
 
-            h2.unwrap()
+            h2.map(|h2| {
+                // keep `stream` from being dropped in order to prevent
+                // it from sending an RST_STREAM frame.
+                std::mem::forget(stream);
+                h2
+            }).unwrap()
         });
 
     let mock = mock.assert_client_handshake().unwrap()