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// 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));
});
}