| // Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| // @dart = 2.9 |
| |
| /// @assertion Stream asyncExpand(Stream convert(T event)) |
| /// Creates a new stream with the events of a stream per original event. |
| /// ... |
| /// If convert returns null, no value is put on the output stream, just as if it |
| /// returned an empty stream. |
| /// |
| /// @description Checks that if convert returns null, no value is put on the |
| /// output stream. |
| /// @author a.semenov@unipro.ru |
| |
| library asyncExpand_A02_t01; |
| import "dart:async"; |
| import "../../../Utils/expect.dart"; |
| |
| void check<T,E>(Stream<T> stream, Stream<E> convert(T event), List<E> expected) { |
| AsyncExpect.data(expected, stream.asyncExpand(convert)); |
| } |
| |
| void test(CreateStreamFunction create) { |
| check(create([]), (_) => null, []); |
| check(create([1,2,3,4,5]), (_) => null, []); |
| |
| check(create([]), (e) => create([e]), []); |
| check(create([1,2,3,4,5]), (e) => e.isOdd ? create([e]) : null, [1,3,5]); |
| check( |
| create(['a',null,'b']), |
| (e) => e!=null ? create([e]) : null, |
| ['a','b'] |
| ); |
| check( |
| create([1,2,3,4,5]), |
| (e) => e.isOdd ? create([e,e]): null, |
| [1,1,3,3,5,5] |
| ); |
| check( |
| create(['a',null,'b']), |
| (e) => e!=null ? create([e,e]) : null, |
| ['a','a','b','b'] |
| ); |
| } |