Migrate redisplayed widgets test to playwright (streamlit#8894)

## Describe your changes

Migrates the redisplayed_widgets cypress e2e test to playwright and
merges it with the `widget_state_heavy_usage` test into one test.

---

**Contribution License Agreement**

By submitting this pull request you agree that all contributions to this
project are made under the Apache 2.0 license.

.github/workflows/playwright-changed-files.yml

@@ -37,8 +37,8 @@ jobs:
       - name: Check changed files
         id: check_changed_files
         env:
-          CHANGED_FILES: ${{ steps.changed-files.outputs.all_changed_and_modified_files }}
-          CHANGED_FILES_COUNT: ${{ steps.changed-files.outputs.all_changed_and_modified_files_count }}
+          CHANGED_FILES: ${{ steps.changed-files.outputs.all_changed_files }}
+          CHANGED_FILES_COUNT: ${{ steps.changed-files.outputs.all_changed_files_count }}
         run: |
           echo "Changed files count: ${CHANGED_FILES_COUNT}"
           echo "$CHANGED_FILES"
@@ -74,7 +74,7 @@ jobs:
         run: |
           cd e2e_playwright;
           rm -rf ./test-results;
-          pytest ${{ steps.changed-files.outputs.all_changed_and_modified_files }} --browser webkit --browser chromium --browser firefox --video retain-on-failure --screenshot only-on-failure --full-page-screenshot --tracing retain-on-failure --output ./test-results/ -n auto --durations=5 -r aR -v
+          pytest ${{ steps.changed-files.outputs.all_changed_files }} --browser webkit --browser chromium --browser firefox --video retain-on-failure --screenshot only-on-failure --full-page-screenshot --tracing retain-on-failure --output ./test-results/ -n auto --durations=5 -r aR -v
       - name: Upload failed test results
         uses: actions/upload-artifact@v4
         if: always()

e2e_playwright/shared/app_utils.py

@@ -69,7 +69,7 @@ def get_image(locator: Locator | Page, caption: str | Pattern[str]) -> Locator:
     return element
 
 
-def get_button(locator: Locator, label: str | Pattern[str]) -> Locator:
+def get_button(locator: Locator | Page, label: str | Pattern[str]) -> Locator:
     """Get a button widget with the given label.
 
     Parameters
@@ -232,8 +232,10 @@ def expect_markdown(
     expected_markdown : str or Pattern[str]
         The expected message to be displayed in the exception.
     """
-    markdown_el = locator.get_by_test_id("stMarkdownContainer").filter(
-        has_text=expected_message
+    markdown_el = (
+        locator.get_by_test_id("stMarkdown")
+        .get_by_test_id("stMarkdownContainer")
+        .filter(has_text=expected_message)
     )
     expect(markdown_el).to_be_visible()
 

e2e_playwright/widget_state_heavy_usage.py → e2e_playwright/widget_state.py

@@ -16,8 +16,21 @@
 
 import streamlit as st
 
-# test for https://github.com/streamlit/streamlit/issues/4836
-number = st.number_input("test", value=100)
+st.header("Widget State - Heavy Usage Test")
+# Test for https://github.com/streamlit/streamlit/issues/4836
+
+number = st.number_input("test", value=0, step=1)
 st.write(number)
 
-time.sleep(1)
+if number:
+    time.sleep(1)
+
+st.header("Widget State - Redisplayed Widget Test")
+# Test for https://github.com/streamlit/streamlit/issues/3512
+
+if st.checkbox("Display widgets"):
+    if st.checkbox("Show hello"):
+        st.write("hello")
+
+    if st.checkbox("Show goodbye", key="c3"):
+        st.write("goodbye")

e2e_playwright/widget_state_test.py

@@ -0,0 +1,72 @@
+# Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022-2024)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from playwright.sync_api import Page, expect
+
+from e2e_playwright.shared.app_utils import click_checkbox, expect_markdown
+
+
+def test_clicking_a_lot_still_keeps_state(app: Page):
+    """Test the the widget state is correctly handled on very fast clicks.
+    Related to: https://github.com/streamlit/streamlit/issues/4836
+    """
+    number_input_down_button = app.get_by_test_id("stNumberInput").locator(
+        "button.step-up"
+    )
+    for _ in range(40):
+        number_input_down_button.click()
+
+    expect_markdown(app, "40")
+
+
+def test_doesnt_save_widget_state_on_redisplay(app: Page):
+    """Test that widget state is not saved when a widget is redisplayed
+    after a rerun.
+
+    Related to: https://github.com/streamlit/streamlit/issues/3512
+    """
+    click_checkbox(app, "Display widgets")
+    click_checkbox(app, "Show hello")
+    expect_markdown(app, "hello")
+
+    # Hide widgets:
+    click_checkbox(app, "Display widgets")
+
+    # Show widgets again:
+    click_checkbox(app, "Display widgets")
+
+    # Should not show hello again -> the widget state was not saved
+    markdown_el = app.get_by_test_id("stMarkdown").filter(has_text="hello")
+    expect(markdown_el).not_to_be_attached()
+
+
+def test_doesnt_save_widget_state_on_redisplay_with_keyed_widget(app: Page):
+    """Test that widget state is not saved when a keyed widget is redisplayed
+    after a rerun.
+
+    Related to: https://github.com/streamlit/streamlit/issues/3512
+    """
+    click_checkbox(app, "Display widgets")
+    click_checkbox(app, "Show goodbye")
+    expect_markdown(app, "goodbye")
+
+    # Hide widgets:
+    click_checkbox(app, "Display widgets")
+
+    # Show widgets again:
+    click_checkbox(app, "Display widgets")
+
+    # Should not show goodbye again -> the widget state was not saved
+    markdown_el = app.get_by_test_id("stMarkdown").filter(has_text="goodbye")
+    expect(markdown_el).not_to_be_attached()