robustify cbsc011

Author: alexcjohnson

tests/integration/callbacks/test_basic_callback.py

@@ -522,6 +522,7 @@ def dynamic_output(*args):
 
     dash_duo.start_server(app)
     dash_duo.wait_for_text_to_equal("#input-9", "Input 9")
+    dash_duo.wait_for_contains_text("#container", "Input 9")
 
     assert call_count.value == 1
     dash_duo.percy_snapshot("test_rendering_layout_calls_callback_once_per_output")