diff --git a/syndicate/src/relay.rs b/syndicate/src/relay.rs
index 30cabcb..ae2ea31 100644
--- a/syndicate/src/relay.rs
+++ b/syndicate/src/relay.rs
@@ -16,7 +16,7 @@ use futures::SinkExt;
 use futures::Stream;
 use futures::StreamExt;
 
-use parking_lot::Mutex;
+pub use parking_lot::Mutex;
 
 use preserves::error::Error as PreservesError;
 use preserves::error::is_eof_io_error;
@@ -89,6 +89,7 @@ pub enum Output {
 type TunnelRelayRef = Arc<Mutex<Option<TunnelRelay>>>;
 
 // There are other kinds of relay. This one has exactly two participants connected to each other.
+#[derive(Debug)]
 pub struct TunnelRelay
 {
     self_ref: TunnelRelayRef,
@@ -222,6 +223,20 @@ impl TunnelRelay {
         initial_oid: Option<sturdy::Oid>,
         output_text: bool,
     ) -> Option<Arc<Cap>> {
+        let (result, tr_ref, output_rx) = TunnelRelay::_run(t, initial_ref, initial_oid, output_text);
+        t.linked_task(Some(AnyValue::symbol("writer")),
+                      output_loop(o, output_rx));
+        t.linked_task(Some(AnyValue::symbol("reader")),
+                      input_loop(t.trace_collector(), t.facet.clone(), i, tr_ref));
+        result
+    }
+
+    pub fn _run(
+        t: &mut Activation,
+        initial_ref: Option<Arc<Cap>>,
+        initial_oid: Option<sturdy::Oid>,
+        output_text: bool,
+    ) -> (Option<Arc<Cap>>, Arc<Mutex<Option<TunnelRelay>>>, UnboundedReceiver<LoanedItem<Vec<u8>>>) {
         let (output_tx, output_rx) = unbounded_channel();
         let tr_ref = Arc::new(Mutex::new(None));
         let self_entity = t.create(TunnelRefEntity {
@@ -247,12 +262,8 @@ impl TunnelRelay {
             |io| Arc::clone(&tr.membranes.import_oid(t, &tr_ref, io).inc_ref().obj));
         dump_membranes!(tr.membranes);
         *tr_ref.lock() = Some(tr);
-        t.linked_task(Some(AnyValue::symbol("writer")),
-                      output_loop(o, output_rx));
-        t.linked_task(Some(AnyValue::symbol("reader")),
-                      input_loop(t.trace_collector(), t.facet.clone(), i, tr_ref));
         t.state.add_exit_hook(&self_entity);
-        result
+        (result, tr_ref, output_rx)
     }
 
     fn deserialize_one(&mut self, t: &mut Activation, bs: &[u8]) -> (Result<P::Packet<AnyValue>, ParseError>, usize) {
@@ -279,13 +290,13 @@ impl TunnelRelay {
         }
     }
 
-    fn handle_inbound_datagram(&mut self, t: &mut Activation, bs: &[u8]) -> ActorResult {
+    pub fn handle_inbound_datagram(&mut self, t: &mut Activation, bs: &[u8]) -> ActorResult {
         tracing::trace!(bytes = ?bs, "inbound datagram");
         let item = self.deserialize_one(t, bs).0?;
         self.handle_inbound_packet(t, item)
     }
 
-    fn handle_inbound_stream(&mut self, t: &mut Activation, buf: &mut BytesMut) -> ActorResult {
+    pub fn handle_inbound_stream(&mut self, t: &mut Activation, buf: &mut BytesMut) -> ActorResult {
         loop {
             tracing::trace!(buffer = ?buf, "inbound stream");
             let (result, count) = self.deserialize_one(t, buf);
@@ -301,7 +312,7 @@ impl TunnelRelay {
         }
     }
 
-    fn handle_inbound_packet(&mut self, t: &mut Activation, p: P::Packet<AnyValue>) -> ActorResult {
+    pub fn handle_inbound_packet(&mut self, t: &mut Activation, p: P::Packet<AnyValue>) -> ActorResult {
         tracing::debug!(packet = ?p, "-->");
         match p {
             P::Packet::Extension(b) => {