inmem: Buffer is a convenience message buffer

Signed-off-by: Solomon Hykes <solomon@docker.com>

inmem/buf.go

@@ -0,0 +1,15 @@
+package inmem
+
+import ()
+
+type Buffer []*Message
+
+func (buf *Buffer) Send(msg *Message, mode int) (Receiver, Sender, error) {
+	(*buf) = append(*buf, msg)
+	return NopReceiver{}, NopSender{}, nil
+}
+
+func (buf *Buffer) Close() error {
+	(*buf) = nil
+	return nil
+}