fix deleting empty row

base/src/test/user_model/test_batch_row_column_diff.rs

@@ -64,7 +64,7 @@ fn undo_redo_after_batch_delete() {
     model.set_user_input(0, 20, 1, "A").unwrap();
     model.set_user_input(0, 1, 20, "B").unwrap();
 
-    // Fill the rows we are about to delete so the diff list can be produced
+    // Fill some of the rows we are about to delete for testing
     for r in 10..15 {
         model.set_user_input(0, r, 1, "tmp").unwrap();
     }
@@ -153,3 +153,75 @@ fn edge_case_single_operation() {
     let list = last_diff_list(&mut model);
     assert_eq!(list.len(), 1);
 }
+
+#[test]
+fn delete_empty_rows() {
+    let base = new_empty_model();
+    let mut model = UserModel::from_model(base);
+
+    // Set data in rows 1 and 10, leaving rows 5-8 empty
+    model.set_user_input(0, 1, 1, "Before").unwrap();
+    model.set_user_input(0, 10, 1, "After").unwrap();
+
+    // Delete empty rows 5-8
+    assert!(model.delete_rows(0, 5, 4).is_ok());
+
+    // Verify shift
+    assert_eq!(model.get_formatted_cell_value(0, 1, 1).unwrap(), "Before");
+    assert_eq!(model.get_formatted_cell_value(0, 6, 1).unwrap(), "After");
+
+    // Verify diffs are in reverse order with empty data
+    let list = last_diff_list(&mut model);
+    assert_eq!(list.len(), 4);
+    let mut expected_row = 8;
+    for diff in &list {
+        match diff {
+            Diff::DeleteRow { row, old_data, .. } => {
+                assert_eq!(*row, expected_row);
+                assert!(old_data.data.is_empty());
+                expected_row -= 1;
+            }
+            _ => panic!("Unexpected diff variant"),
+        }
+    }
+
+    // Undo/redo
+    model.undo().unwrap();
+    assert_eq!(model.get_formatted_cell_value(0, 10, 1).unwrap(), "After");
+    model.redo().unwrap();
+    assert_eq!(model.get_formatted_cell_value(0, 6, 1).unwrap(), "After");
+}
+
+#[test]
+fn delete_mixed_empty_and_filled_rows() {
+    let base = new_empty_model();
+    let mut model = UserModel::from_model(base);
+
+    // Alternating filled and empty rows
+    model.set_user_input(0, 5, 1, "Row5").unwrap();
+    model.set_user_input(0, 7, 1, "Row7").unwrap();
+    model.set_user_input(0, 9, 1, "Row9").unwrap();
+    model.set_user_input(0, 10, 1, "After").unwrap();
+
+    assert!(model.delete_rows(0, 5, 5).is_ok());
+    assert_eq!(model.get_formatted_cell_value(0, 5, 1).unwrap(), "After");
+
+    // Verify mix of empty and filled row diffs
+    let list = last_diff_list(&mut model);
+    assert_eq!(list.len(), 5);
+    let filled_count = list
+        .iter()
+        .filter(|diff| match diff {
+            Diff::DeleteRow { old_data, .. } => !old_data.data.is_empty(),
+            _ => false,
+        })
+        .count();
+    assert_eq!(filled_count, 3);
+
+    // Undo
+    model.undo().unwrap();
+    assert_eq!(model.get_formatted_cell_value(0, 5, 1).unwrap(), "Row5");
+    assert_eq!(model.get_formatted_cell_value(0, 7, 1).unwrap(), "Row7");
+    assert_eq!(model.get_formatted_cell_value(0, 9, 1).unwrap(), "Row9");
+    assert_eq!(model.get_formatted_cell_value(0, 10, 1).unwrap(), "After");
+}