Datatable remove row (#2253)

* Checking in remove_row progress

* Ensuring structures updated correctly when row deleted

* Clamping index

* Failed attempt

* Removing rows

* Update a type hint in DataTable

* Remove some code that wasnt required

* Use index syntax instead of get

* Add DataTable remove row test

* Snapshot tests for removing rows

* Add a docstring for DataTable.remove_row method

* Update changelog regarding DataTable.remove_row

* Add check_idle call to remove_row

tests/snapshot_tests/snapshot_apps/data_table_remove_row.py

@@ -0,0 +1,51 @@
+from textual.app import App, ComposeResult
+from textual.binding import Binding
+from textual.widgets import DataTable
+
+ROWS = [
+    ("lane", "swimmer", "country", "time"),
+    (5, "Chad le Clos", "South Africa", 51.14),
+    (4, "Joseph Schooling", "Singapore", 50.39),
+    (2, "Michael Phelps", "United States", 51.14),
+    (6, "László Cseh", "Hungary", 51.14),
+    (3, "Li Zhuhao", "China", 51.26),
+    (8, "Mehdy Metella", "France", 51.58),
+    (7, "Tom Shields", "United States", 51.73),
+    (10, "Darren Burns", "Scotland", 51.84),
+    (1, "Aleksandr Sadovnikov", "Russia", 51.84),
+]
+
+
+class TableApp(App):
+    """Snapshot app for testing removal of rows.
+    Removes several rows, so we can check that the display of the
+    DataTable updates as expected."""
+
+    BINDINGS = [
+        Binding("r", "remove_row", "Remove Row"),
+    ]
+
+    def compose(self) -> ComposeResult:
+        yield DataTable()
+
+    def on_mount(self) -> None:
+        table = self.query_one(DataTable)
+        table.focus()
+        rows = iter(ROWS)
+        column_labels = next(rows)
+        for column in column_labels:
+            table.add_column(column, key=column)
+
+        for row in rows:
+            table.add_row(*row, key=str(row[0]))
+
+    def action_remove_row(self):
+        table = self.query_one(DataTable)
+        table.remove_row("2")
+        table.remove_row("8")
+        table.remove_row("1")
+
+
+app = TableApp()
+if __name__ == "__main__":
+    app.run()