assertSizeIs(1, rows);
final ArrayList<KeyValue> kvs = rows.get(0);
final KeyValue kv = kvs.get(0);
assertSizeIs(1, kvs);
assertEq("s" + n, kv.key());
assertEq("q", kv.qualifier());
assertEq("v" + n, kv.value());
return scanner.nextRows(1).addCallback(this);
} catch (AssertionError e) {
// Deferred doesn't catch Errors on purpose, so transform any
// assertion failure into an Exception.