Merge pull request #1610 from Textualize/fix-1607

Fix #1607 to allow programmatic style changes

tests/css/test_programmatic_style_changes.py

@@ -0,0 +1,95 @@
+import pytest
+
+from textual.app import App
+from textual.containers import Grid
+from textual.screen import Screen
+from textual.widgets import Label
+
+
+@pytest.mark.parametrize(
+    "style, value",
+    [
+        ("grid_size_rows", 3),
+        ("grid_size_columns", 3),
+        ("grid_gutter_vertical", 4),
+        ("grid_gutter_horizontal", 4),
+        ("grid_rows", "1fr 3fr"),
+        ("grid_columns", "1fr 3fr"),
+    ],
+)
+async def test_programmatic_style_change_updates_children(style: str, value: object):
+    """Regression test for #1607 https://github.com/Textualize/textual/issues/1607
+
+    Some programmatic style changes to a widget were not updating the layout of the
+    children widgets, which seemed to be happening when the style change did not affect
+    the size of the widget but did affect the layout of the children.
+
+    This test, in particular, checks the attributes that _should_ affect the size of the
+    children widgets.
+    """
+
+    class MyApp(App[None]):
+        CSS = """
+        Grid { grid-size: 2 2; }
+        Label { width: 100%; height: 100%; }
+        """
+
+        def compose(self):
+            yield Grid(
+                Label("one"),
+                Label("two"),
+                Label("three"),
+                Label("four"),
+            )
+
+    app = MyApp()
+
+    async with app.run_test() as pilot:
+        sizes = [(lbl.size.width, lbl.size.height) for lbl in app.screen.query(Label)]
+
+        setattr(app.query_one(Grid).styles, style, value)
+        await pilot.pause()
+
+        assert sizes != [
+            (lbl.size.width, lbl.size.height) for lbl in app.screen.query(Label)
+        ]
+
+
+@pytest.mark.parametrize(
+    "style, value",
+    [
+        ("align_horizontal", "right"),
+        ("align_vertical", "bottom"),
+        ("align", ("right", "bottom")),
+    ],
+)
+async def test_programmatic_align_change_updates_children_position(
+    style: str, value: str
+):
+    """Regression test for #1607 for the align(_xxx) styles.
+
+    See https://github.com/Textualize/textual/issues/1607.
+    """
+
+    class MyApp(App[None]):
+        CSS = "Grid { grid-size: 2 2; }"
+
+        def compose(self):
+            yield Grid(
+                Label("one"),
+                Label("two"),
+                Label("three"),
+                Label("four"),
+            )
+
+    app = MyApp()
+
+    async with app.run_test() as pilot:
+        offsets = [(lbl.region.x, lbl.region.y) for lbl in app.screen.query(Label)]
+
+        setattr(app.query_one(Grid).styles, style, value)
+        await pilot.pause()
+
+        assert offsets != [
+            (lbl.region.x, lbl.region.y) for lbl in app.screen.query(Label)
+        ]

tests/snapshot_tests/snapshot_apps/programmatic_scrollbar_gutter_change.py

@@ -0,0 +1,29 @@
+from textual.app import App
+from textual.containers import Grid
+from textual.widgets import Label
+
+
+class ProgrammaticScrollbarGutterChange(App[None]):
+    CSS = """
+    Grid { grid-size: 2 2; scrollbar-size: 5 5; }
+    Label { width: 100%; height: 100%; background: red; }
+    """
+
+    def compose(self):
+        yield Grid(
+            Label("one"),
+            Label("two"),
+            Label("three"),
+            Label("four"),
+        )
+
+    def on_key(self, event):
+        if event.key == "s":
+            self.query_one(Grid).styles.scrollbar_gutter = "stable"
+
+
+app = ProgrammaticScrollbarGutterChange()
+
+
+if __name__ == "__main__":
+    app().run()

tests/snapshot_tests/test_snapshots.py

@@ -179,6 +179,16 @@ def test_nested_auto_heights(snap_compare):
     assert snap_compare("snapshot_apps/nested_auto_heights.py", press=["1", "2", "_"])
 
 
+def test_programmatic_scrollbar_gutter_change(snap_compare):
+    """Regression test for #1607 https://github.com/Textualize/textual/issues/1607
+
+    See also tests/css/test_programmatic_style_changes.py for other related regression tests.
+    """
+    assert snap_compare(
+        "snapshot_apps/programmatic_scrollbar_gutter_change.py", press=["s"]
+    )
+
+
 # --- Other ---