Test: log number of active read/write pumps in case of error.

Also dump goroutines to help tracking down what is blocking cleanup.

hub_test.go

@@ -284,7 +284,8 @@ func WaitForHub(ctx context.Context, t *testing.T, h *Hub) {
 		case <-ctx.Done():
 			h.mu.Lock()
 			h.ru.Lock()
-			t.Errorf("Error waiting for clients %+v / rooms %+v / sessions %+v to terminate: %s", h.clients, h.rooms, h.sessions, ctx.Err())
+			dumpGoroutines()
+			t.Errorf("Error waiting for clients %+v / rooms %+v / sessions %+v / %d read / %d write to terminate: %s", h.clients, h.rooms, h.sessions, readActive, writeActive, ctx.Err())
 			h.ru.Unlock()
 			h.mu.Unlock()
 			return

testutils_test.go

@@ -68,7 +68,12 @@ func ensureNoGoroutinesLeak(t *testing.T, f func(t *testing.T)) {
 	}
 
 	if after != before {
-		profile.WriteTo(os.Stderr, 2) // nolint
+		dumpGoroutines()
 		t.Fatalf("Number of Go routines has changed from %d to %d", before, after)
 	}
 }
+
+func dumpGoroutines() {
+	profile := pprof.Lookup("goroutine")
+	profile.WriteTo(os.Stderr, 2) // nolint
+}