fix: make sure page.goto navigates away from pages with beforeunload (#898)

Author: mxschmitt

playwright/_impl/_page.py

@@ -37,6 +37,7 @@
     from_nullable_channel,
 )
 from playwright._impl._console_message import ConsoleMessage
+from playwright._impl._dialog import Dialog
 from playwright._impl._download import Download
 from playwright._impl._element_handle import ElementHandle
 from playwright._impl._event_context_manager import EventContextManagerImpl
@@ -242,11 +243,14 @@ def _on_crash(self) -> None:
         self.emit(Page.Events.Crash)
 
     def _on_dialog(self, params: Any) -> None:
-        dialog = from_channel(params["dialog"])
+        dialog = cast(Dialog, from_channel(params["dialog"]))
         if self.listeners(Page.Events.Dialog):
             self.emit(Page.Events.Dialog, dialog)
         else:
-            asyncio.create_task(dialog.dismiss())
+            if dialog.type == "beforeunload":
+                asyncio.create_task(dialog.accept())
+            else:
+                asyncio.create_task(dialog.dismiss())
 
     def _on_download(self, params: Any) -> None:
         url = params["url"]

tests/async/test_page.py

@@ -75,6 +75,16 @@ async def test_close_should_not_run_beforeunload_by_default(context, server):
     await page.close()
 
 
+async def test_should_be_able_to_navigate_away_from_page_with_before_unload(
+    server: Server, page: Page
+):
+    await page.goto(server.PREFIX + "/beforeunload.html")
+    # We have to interact with a page so that 'beforeunload' handlers
+    # fire.
+    await page.click("body")
+    await page.goto(server.EMPTY_PAGE)
+
+
 async def test_close_should_set_the_page_close_state(context):
     page = await context.new_page()
     assert page.is_closed() is False