text: import json
  import time
  from pytest import approx
  from dash import Dash, Input, State, Output, dcc, html
  from dash.exceptions import PreventUpdate
  import dash.testing.wait as wait
  
  
  def test_stcp001_clear_data_on_all_types(store_app, dash_dcc):
      dash_dcc.start_server(store_app)
  
      assert dash_dcc.wait_for_contains_text("#output", store_app.uuid)
  
      dash_dcc.multiple_click("#btn", 3)
      wait.until(lambda: dash_dcc.get_local_storage() == {"n_clicks": 3}, timeout=1)
  
      # button click sets clear_data=True on all type of stores
      dash_dcc.find_element("#clear-btn").click()
  
      dash_dcc.wait_for_text_to_equal("#output", "")
  
      assert (
          not dash_dcc.find_element("#output").text
          and not dash_dcc.get_local_storage()
          and not dash_dcc.get_session_storage()
      ), "set clear_data=True should clear all data in three storage types"
  
      assert dash_dcc.get_logs() == []
  
  
  def test_stcp002_modified_ts(store_app, dash_dcc):
      app = Dash(__name__)
      app.layout = html.Div(
          [
              dcc.Store(id="initial-storage", storage_type="session"),
              html.Button("set-init-storage", id="set-init-storage"),
              html.Div(id="init-output"),
          ]
      )
  
      @app.callback(
          Output("initial-storage", "data"),
          [Input("set-init-storage", "n_clicks")],
      )
      def on_init(n_clicks):
          if n_clicks is None:
              raise PreventUpdate
          return "initialized"
  
      @app.callback(
          Output("init-output", "children"),
          [Input("initial-storage", "modified_timestamp")],
          [State("initial-storage", "data")],
      )
      def init_output(ts, data):
          return json.dumps({"data": data, "ts": ts})
  
      dash_dcc.start_server(app)
  
      dash_dcc.find_element("#set-init-storage").click()
      # the python ts ends at seconds while javascript one ends at ms
      ts = float(time.time() * 1000)
  
      wait.until(
          lambda: "initialized" in dash_dcc.find_element("#init-output").text, timeout=3
      )
  
      output_data = json.loads(dash_dcc.find_element("#init-output").text)
  
      assert (
          output_data.get("data") == "initialized"
      ), "the data should be the text set in on_init"
      assert ts == approx(
          output_data.get("ts"), abs=40
      ), "the modified_timestamp should be updated right after the click action"
  
      assert dash_dcc.get_logs() == []
  
  
  def test_stcp003_initial_falsy(dash_dcc):
      app = Dash(__name__)
      app.layout = html.Div(
          [
              html.Div(
                  [
                      storage_type,
                      dcc.Store(
                          storage_type=storage_type, id="zero-" + storage_type, data=0
                      ),
                      dcc.Store(
                          storage_type=storage_type,
                          id="false-" + storage_type,
                          data=False,
                      ),
                      dcc.Store(
                          storage_type=storage_type, id="null-" + storage_type, data=None
                      ),
                      dcc.Store(
                          storage_type=storage_type, id="empty-" + storage_type, data=""
                      ),
                  ]
              )
              for storage_type in ("memory", "local", "session")
          ],
          id="content",
      )
  
      dash_dcc.start_server(app)
      dash_dcc.wait_for_text_to_equal("#content", "memory\nlocal\nsession")
  
      for storage_type in ("local", "session"):
          getter = getattr(dash_dcc, f"get_{storage_type}_storage")
          assert getter("zero-" + storage_type) == 0, storage_type
          assert getter("false-" + storage_type) is False, storage_type
          assert getter("null-" + storage_type) is None, storage_type
          assert getter("empty-" + storage_type) == "", storage_type
  
      assert dash_dcc.get_logs() == []
  
  
  def test_stcp004_remount_store_component(dash_dcc):
      app = Dash(__name__, suppress_callback_exceptions=True)
  
      content = html.Div(
          [
              dcc.Store(id="memory", storage_type="memory"),
              dcc.Store(id="local", storage_type="local"),
              dcc.Store(id="session", storage_type="session"),
              html.Button("click me", id="btn"),
              html.Button("clear data", id="clear-btn"),
              html.Div(id="output"),
          ]
      )
  
      app.layout = html.Div([html.Button("start", id="start"), html.Div(id="content")])
  
      @app.callback(Output("content", "children"), [Input("start", "n_clicks")])
      def start(n):
          return content if n else "init"
  
      @app.callback(
          Output("output", "children"),
          [
              Input("memory", "modified_timestamp"),
              Input("local", "modified_timestamp"),
              Input("session", "modified_timestamp"),
          ],
          [State("memory", "data"), State("local", "data"), State("session", "data")],
      )
      def write_memory(tsm, tsl, tss, datam, datal, datas):
          return json.dumps([datam, datal, datas])
  
      @app.callback(
          [
              Output("local", "clear_data"),
              Output("memory", "clear_data"),
              Output("session", "clear_data"),
          ],
          [Input("clear-btn", "n_clicks")],
      )
      def on_clear(n_clicks):
          if n_clicks is None:
              raise PreventUpdate
          return True, True, True
  
      @app.callback(
          [Output("memory", "data"), Output("local", "data"), Output("session", "data")],
          [Input("btn", "n_clicks")],
      )
      def on_click(n_clicks):
          return ({"n_clicks": n_clicks},) * 3
  
      dash_dcc.start_server(app)
  
      dash_dcc.wait_for_text_to_equal("#content", "init")
  
      dash_dcc.find_element("#start").click()
      dash_dcc.wait_for_text_to_equal(
          "#output", '[{"n_clicks": null}, {"n_clicks": null}, {"n_clicks": null}]'
      )
  
      dash_dcc.find_element("#btn").click()
      dash_dcc.wait_for_text_to_equal(
          "#output", '[{"n_clicks": 1}, {"n_clicks": 1}, {"n_clicks": 1}]'
      )
  
      dash_dcc.find_element("#clear-btn").click()
      dash_dcc.wait_for_text_to_equal("#output", "[null, null, null]")
  
      dash_dcc.find_element("#btn").click()
      dash_dcc.wait_for_text_to_equal(
          "#output", '[{"n_clicks": 2}, {"n_clicks": 2}, {"n_clicks": 2}]'
      )
  
      # now remount content components
      dash_dcc.find_element("#start").click()
      dash_dcc.wait_for_text_to_equal(
          "#output", '[{"n_clicks": null}, {"n_clicks": null}, {"n_clicks": null}]'
      )
  
      dash_dcc.find_element("#btn").click()
      dash_dcc.wait_for_text_to_equal(
          "#output", '[{"n_clicks": 1}, {"n_clicks": 1}, {"n_clicks": 1}]'
      )
  
      assert dash_dcc.get_logs() == []
  