Improve test reliability

Author: KoolADE85

components/dash-core-components/tests/integration/misc/test_persistence.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 import json
+from time import sleep
 from selenium.webdriver.common.keys import Keys
 
 from dash import Dash, Input, Output, dcc, html
@@ -133,12 +134,14 @@ def make_output(*args):
     dash_dcc.find_element("#dropdownsingle .dash-dropdown-search").send_keys(
         "one" + Keys.ENTER
     )
+    sleep(0.2)
     dash_dcc.find_element("#dropdownsingle .dash-dropdown-option").click()
 
     dash_dcc.find_element("#dropdownmulti").click()
     dash_dcc.find_element("#dropdownmulti .dash-dropdown-search").send_keys(
         "six" + Keys.ENTER
     )
+    sleep(0.2)
     dash_dcc.find_element("#dropdownmulti .dash-dropdown-option").click()
 
     dash_dcc.find_element("#input").send_keys(" maybe")