// Copyright 2014 The Flutter Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. import 'package:flutter/foundation.dart'; import 'package:flutter_test/flutter_test.dart'; int yieldCount = 0; Iterable<int> range(int start, int end) sync* { assert(yieldCount == 0); for (int index = start; index <= end; index += 1) { yieldCount += 1; yield index; } } void main() { setUp(() { yieldCount = 0; }); test('The Caching Iterable: length caches', () { final Iterable<int> i = CachingIterable<int>(range(1, 5).iterator); expect(yieldCount, equals(0)); expect(i.length, equals(5)); expect(yieldCount, equals(5)); expect(i.length, equals(5)); expect(yieldCount, equals(5)); expect(i.last, equals(5)); expect(yieldCount, equals(5)); expect(i, equals(<int>[1, 2, 3, 4, 5])); expect(yieldCount, equals(5)); }); test('The Caching Iterable: laziness', () { final Iterable<int> i = CachingIterable<int>(range(1, 5).iterator); expect(yieldCount, equals(0)); expect(i.first, equals(1)); expect(yieldCount, equals(1)); expect(i.firstWhere((int i) => i == 3), equals(3)); expect(yieldCount, equals(3)); expect(i.last, equals(5)); expect(yieldCount, equals(5)); }); test('The Caching Iterable: where and map', () { final Iterable<int> integers = CachingIterable<int>(range(1, 5).iterator); expect(yieldCount, equals(0)); final Iterable<int> evens = integers.where((int i) => i.isEven); expect(yieldCount, equals(0)); expect(evens.first, equals(2)); expect(yieldCount, equals(2)); expect(integers.first, equals(1)); expect(yieldCount, equals(2)); expect(evens.map<int>((int i) => i + 1), equals(<int>[3, 5])); expect(yieldCount, equals(5)); expect(evens, equals(<int>[2, 4])); expect(yieldCount, equals(5)); expect(integers, equals(<int>[1, 2, 3, 4, 5])); expect(yieldCount, equals(5)); }); test('The Caching Iterable: take and skip', () { final Iterable<int> integers = CachingIterable<int>(range(1, 5).iterator); expect(yieldCount, equals(0)); final Iterable<int> secondTwo = integers.skip(1).take(2); expect(yieldCount, equals(0)); expect(secondTwo, equals(<int>[2, 3])); expect(yieldCount, equals(3)); final Iterable<int> result = integers.takeWhile((int i) => i < 4).skipWhile((int i) => i < 3); expect(result, equals(<int>[3])); expect(yieldCount, equals(4)); expect(integers, equals(<int>[1, 2, 3, 4, 5])); expect(yieldCount, equals(5)); }); test('The Caching Iterable: expand', () { final Iterable<int> integers = CachingIterable<int>(range(1, 5).iterator); expect(yieldCount, equals(0)); final Iterable<int> expanded1 = integers.expand<int>((int i) => <int>[i, i]); expect(yieldCount, equals(0)); expect(expanded1, equals(<int>[1, 1, 2, 2, 3, 3, 4, 4, 5, 5])); expect(yieldCount, equals(5)); final Iterable<int> expanded2 = integers.expand<int>((int i) => <int>[i, i]); expect(yieldCount, equals(5)); expect(expanded2, equals(<int>[1, 1, 2, 2, 3, 3, 4, 4, 5, 5])); expect(yieldCount, equals(5)); }); }