Add tests for Horizontal/Vertical(Scroll) containers.

tests/snapshot_tests/snapshot_apps/layout_containers.py

@@ -0,0 +1,56 @@
+"""
+App to test layout containers.
+"""
+
+from typing import Iterable
+
+from textual.app import App, ComposeResult
+from textual.containers import (
+    Grid,
+    Horizontal,
+    HorizontalScroll,
+    Vertical,
+    VerticalScroll,
+)
+from textual.widget import Widget
+from textual.widgets import Button, Input, Label
+
+
+def sub_compose() -> Iterable[Widget]:
+    yield Button.success("Accept")
+    yield Button.error("Decline")
+    yield Input()
+    yield Label("\n\n".join([str(n * 1_000_000) for n in range(10)]))
+
+
+class MyApp(App[None]):
+    CSS = """
+    Grid {
+        grid-size: 2 2;
+        grid-rows: 1fr;
+        grid-columns: 1fr;
+    }
+    Grid > Widget {
+        width: 100%;
+        height: 100%;
+    }
+    Input {
+        width: 80;
+    }
+    """
+
+    def compose(self) -> ComposeResult:
+        with Grid():
+            with Horizontal():
+                yield from sub_compose()
+            with HorizontalScroll():
+                yield from sub_compose()
+            with Vertical():
+                yield from sub_compose()
+            with VerticalScroll():
+                yield from sub_compose()
+
+
+app = MyApp()
+if __name__ == "__main__":
+    app.run()

tests/snapshot_tests/test_snapshots.py

@@ -48,6 +48,10 @@ def test_dock_layout_sidebar(snap_compare):
     assert snap_compare(LAYOUT_EXAMPLES_DIR / "dock_layout2_sidebar.py")
 
 
+def test_layout_containers(snap_compare):
+    assert snap_compare(SNAPSHOT_APPS_DIR / "layout_containers.py")
+
+
 # --- Widgets - rendering and basic interactions ---
 # Each widget should have a canonical example that is display in the docs.
 # When adding a new widget, ideally we should also create a snapshot test
@@ -170,9 +174,11 @@ def test_content_switcher_example_initial(snap_compare):
 
 
 def test_content_switcher_example_switch(snap_compare):
-    assert snap_compare(WIDGET_EXAMPLES_DIR / "content_switcher.py", press=[
-        "tab", "tab", "enter", "wait:500"
-    ], terminal_size=(50, 50))
+    assert snap_compare(
+        WIDGET_EXAMPLES_DIR / "content_switcher.py",
+        press=["tab", "tab", "enter", "wait:500"],
+        terminal_size=(50, 50),
+    )
 
 
 # --- CSS properties ---
@@ -234,6 +240,7 @@ def test_programmatic_scrollbar_gutter_change(snap_compare):
 # --- CLI Preview Apps ---
 # For our CLI previews e.g. `textual easing`, `textual colors` etc, we have snapshots
 
+
 def test_borders_preview(snap_compare):
     assert snap_compare(CLI_PREVIEWS_DIR / "borders.py", press=["tab", "enter"])