throws Exception {
AlphanumericDataSource d = (AlphanumericDataSource) ds
.getDataSource(dsName, DataSourceFactory.UNDOABLE);
d.beginTrans();
d.deleteRow(0);
assertTrue(d.canUndo());
d.removeField(1);
assertTrue(!d.canRedo());
assertTrue(!d.canUndo());
d.rollBackTrans();
}