test

tests/test_compositor.py

@@ -0,0 +1,39 @@
+from textual.app import App, ComposeResult
+from textual.containers import Container
+from textual.widgets import Static
+
+
+async def test_compositor_scroll_placements():
+    """Regression test for https://github.com/Textualize/textual/issues/5249"""
+
+    class ScrollApp(App):
+        CSS = """
+        Screen {
+            overflow: scroll;
+        }
+        Container {
+            width: 200vw;
+        }
+        #hello {
+            width: 20;
+            height: 10;
+            offset: 50 10;
+            background: blue;
+            color: white;
+        }
+        """
+
+        def compose(self) -> ComposeResult:
+            with Container():
+                yield Static("Hello", id="hello")
+
+        def on_mount(self) -> None:
+            self.query_one("Screen").scroll_to(20, 0, animate=False)
+
+    app = ScrollApp()
+    async with app.run_test() as pilot:
+        await pilot.pause()
+        static = app.query_one("#hello")
+        widgets = app.screen._compositor.visible_widgets
+        # The static wasn't scrolled out of view, and should be visible
+        assert static in widgets