Test cell_padding assignment refreshes data table.

src/textual/widgets/_data_table.py

@@ -330,6 +330,9 @@ class DataTable(ScrollView, Generic[CellType], can_focus=True):
     )
     """The coordinate of the `DataTable` that is being hovered."""
 
+    def watch_cell_padding(self) -> None:
+        self._clear_caches()
+
     class CellHighlighted(Message):
         """Posted when the cursor moves to highlight a new cell.
 
@@ -1052,6 +1055,9 @@ class DataTable(ScrollView, Generic[CellType], can_focus=True):
     def watch_zebra_stripes(self) -> None:
         self._clear_caches()
 
+    def watch_cell_padding(self) -> None:
+        self._clear_caches()
+
     def watch_hover_coordinate(self, old: Coordinate, value: Coordinate) -> None:
         self.refresh_coordinate(old)
         self.refresh_coordinate(value)

tests/snapshot_tests/snapshot_apps/data_table_cell_padding.py

@@ -16,6 +16,12 @@ class TableApp(App):
             dt.add_row("value", "value", "val")
             yield dt
 
+    def key_a(self):
+        self.query(DataTable).last().cell_padding = 20
+
+    def key_b(self):
+        self.query(DataTable).last().cell_padding = 10
+
 
 app = TableApp()
 if __name__ == "__main__":

tests/snapshot_tests/test_snapshots.py

@@ -172,6 +172,13 @@ def test_datatable_cell_padding(snap_compare):
     assert snap_compare(SNAPSHOT_APPS_DIR / "data_table_cell_padding.py")
 
 
+def test_datatable_change_cell_padding(snap_compare):
+    # Check that horizontal cell padding is respected.
+    assert snap_compare(
+        SNAPSHOT_APPS_DIR / "data_table_cell_padding.py", press=["a", "b"]
+    )
+
+
 def test_footer_render(snap_compare):
     assert snap_compare(WIDGET_EXAMPLES_DIR / "footer.py")