From 2b547caa75d0c2e7d976d19d3ccb0ee20f4666cf Mon Sep 17 00:00:00 2001
From: Solomon Hykes <solomon@docker.com>
Date: Mon, 12 May 2014 05:00:09 +0000
Subject: [PATCH] Fix Hub and StackSender to honor modes

StackSender.Send and Hub.Send now return a valid Sender and Receiver
when the corresponding flags are set in `mode`.

Signed-off-by: Solomon Hykes <solomon@docker.com>
---
 utils/hub_test.go | 12 +++++++++---
 utils/stack.go    |  2 +-
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/utils/hub_test.go b/utils/hub_test.go
index 3ecd5a0a61..c9b40a4817 100644
--- a/utils/hub_test.go
+++ b/utils/hub_test.go
@@ -9,11 +9,17 @@ import (
 func TestHubSendEmpty(t *testing.T) {
 	hub := NewHub()
 	// Send to empty hub should silently drop
-	if r, w, err := hub.Send(&beam.Message{Name: "hello", Args: nil}, beam.R|beam.W); err != nil {
+	r, w, err := hub.Send(&beam.Message{Name: "hello", Args: nil}, beam.R|beam.W)
+	// Send must not return an error
+	if err != nil {
 		t.Fatal(err)
-	} else if r != nil {
+	}
+	// We set beam.R, so a valid receiver must be returned
+	if r == nil {
 		t.Fatalf("%#v", r)
-	} else if w != nil {
+	}
+	// We set beam.W, so a valid receiver must be returned
+	if w == nil {
 		t.Fatalf("%#v", w)
 	}
 }
diff --git a/utils/stack.go b/utils/stack.go
index 1309402b83..a8b1f6baea 100644
--- a/utils/stack.go
+++ b/utils/stack.go
@@ -38,7 +38,7 @@ func (s *StackSender) Send(msg *beam.Message, mode int) (r beam.Receiver, w beam
 		return r, w, err
 	}
 	// Silently drop messages if no valid backend is available.
-	return nil, nil, nil
+	return NopSender{}.Send(msg, mode)
 }
 
 func (s *StackSender) Add(dst beam.Sender) *StackSender {