add test

CHANGELOG.md

@@ -30,6 +30,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - Numbers in a descendant-combined selector no longer cause an error https://github.com/Textualize/textual/issues/1836
 - Fixed superfluous scrolling when focusing a docked widget https://github.com/Textualize/textual/issues/1816
+- Fixes walk_children which was returning more than one screen https://github.com/Textualize/textual/issues/1846
+- Fixed issue with watchers fired for detached nodes https://github.com/Textualize/textual/issues/1846
 
 ## [0.11.1] - 2023-02-17
 

src/textual/reactive.py

@@ -239,10 +239,9 @@ class Reactive(Generic[ReactiveType]):
                     )
                 )
 
-        if obj.is_attached:
-            watch_function = getattr(obj, f"watch_{name}", None)
-            if callable(watch_function):
-                invoke_watcher(watch_function, old_value, value)
+        watch_function = getattr(obj, f"watch_{name}", None)
+        if callable(watch_function):
+            invoke_watcher(watch_function, old_value, value)
 
         # Process "global" watchers
         watchers: list[tuple[Reactable, Callable]]

tests/test_screens.py

@@ -11,6 +11,22 @@ skip_py310 = pytest.mark.skipif(
 )
 
 
+async def test_screen_walk_children():
+    """Test query only reports active screen."""
+
+    class ScreensApp(App):
+        pass
+
+    app = ScreensApp()
+    async with app.run_test() as pilot:
+        screen1 = Screen()
+        screen2 = Screen()
+        pilot.app.push_screen(screen1)
+        assert list(pilot.app.query("*")) == [screen1]
+        pilot.app.push_screen(screen2)
+        assert list(pilot.app.query("*")) == [screen2]
+
+
 async def test_installed_screens():
     class ScreensApp(App):
         SCREENS = {