.

go/internal/xtracing/tracetest/tracetest.go

@@ -253,8 +253,11 @@ func (t *T) queuenak(msg *_Msg, why string) {
 }
 
 
-// XXX doc; naming
-// XXX document routeEvent requirements
+// SetEventRouter tells t to which stream an event should go.
+//
+// It should be called not more than once.
+// Before SetEventRouter is called, all events go to "default" stream.
+// XXX naming
 func (t *T) SetEventRouter(routeEvent func(event interface{}) (stream string)) {
 	t.mu.Lock()
 	defer t.mu.Unlock()