Module
x/lazy/test/aggregates.spec.ts
A linq-like lazy-evaluation enumerable/iteration library that aims to support deno, node & browser
Latest
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const test = Deno.test;
test('aggregate', () => { assertEquals( Lazy.from([1, 2, 3]).aggregate((acc, curr) => acc + curr, 0), 1 + 2 + 3, ); assertEquals( Lazy.from([1, 2, 3, 4]).aggregate((acc, curr) => acc + curr, 0), 1 + 2 + 3 + 4, ); assertEquals( Lazy.from([1, 2, 3, 4]).aggregate((acc, curr) => acc * curr, 1), 1 * 2 * 3 * 4, ); assertEquals( Lazy.from([1, 2, 3]).aggregate((acc, curr) => acc + curr, ''), '123', ); assertEquals( Lazy.from([1, 2, 3]).aggregate((acc, curr) => acc + curr), 1 + 2 + 3, );});
test('all', () => { assertEquals( Lazy.from([true, true, true, true]).all(v => v), true, ); assertEquals( Lazy.from([false, true, true, true]).all(v => v), false, ); assertEquals( Lazy.from([true, false, true, true]).all(v => v), false, ); assertEquals( Lazy.from([true, true, false, true]).all(v => v), false, ); assertEquals( Lazy.from([true, true, true, false]).all(v => v), false, );});
test('any', () => { assertEquals( Lazy.from([true, true, true, true]).any(v => v), true, ); assertEquals( Lazy.from([false, true, true, true]).any(v => v), true, ); assertEquals( Lazy.from([false, false, true, true]).any(v => v), true, ); assertEquals( Lazy.from([false, false, false, true]).any(v => v), true, ); assertEquals( Lazy.from([false, false, false, false]).any(v => v), false, );
assertEquals(Lazy.from([]).any(), false); assertEquals(Lazy.from([1]).any(), true);});
test('average', () => { const avg = (lst: number[]) => lst.reduce((prev, curr) => prev + curr) / lst.length;
let orig = [1, 2, 3, 4]; assertEquals(Lazy.from(orig).average(), avg(orig));
orig = [4, 3, 2, 1]; assertEquals(Lazy.from(orig).average(), avg(orig));
orig = [1, 2, 3, 4, 9, 8, 6]; assertEquals(Lazy.from(orig).average(), avg(orig));
assertThrows(() => Lazy.from([true]).average());
const objs = [ { value: 1 }, { value: 2 }, { value: 3 }, { value: 4 }, { value: 5 }, ]; assertEquals( Lazy.from(objs).average(o => o.value), avg(objs.map(o => o.value)), );});
test('contains', () => { const orig = [1, 2, 3, 4, 5]; assertEquals(Lazy.from(orig).contains(1), true); assertEquals(Lazy.from(orig).contains(2), true); assertEquals(Lazy.from(orig).contains(3), true); assertEquals(Lazy.from(orig).contains(4), true); assertEquals(Lazy.from(orig).contains(5), true); assertEquals(Lazy.from(orig).contains(6), false); assertEquals(Lazy.from(orig).contains(7), false);
const comparer = (a: number, b: number) => a.toString() === b.toString(); assertEquals(Lazy.from(orig).contains('1' as any, comparer), true); assertEquals(Lazy.from(orig).contains('2' as any, comparer), true); assertEquals(Lazy.from(orig).contains('3' as any, comparer), true); assertEquals(Lazy.from(orig).contains('4' as any, comparer), true); assertEquals(Lazy.from(orig).contains('5' as any, comparer), true); assertEquals(Lazy.from(orig).contains('6' as any, comparer), false); assertEquals(Lazy.from(orig).contains('7' as any, comparer), false);});
test('count', () => { // Test direct array access. assertEquals(Lazy.from([]).count(), 0); assertEquals(Lazy.from([1]).count(), 1); assertEquals(Lazy.from([1, 2]).count(), 2); assertEquals(Lazy.from([1, 2, 3]).count(), 3); assertEquals(Lazy.from([1, 2, 3, 4]).count(), 4);
assertEquals( Lazy.from([]).count(i => i % 2 === 0), 0, ); assertEquals( Lazy.from([1]).count(i => i % 2 === 0), 0, ); assertEquals( Lazy.from([1, 2]).count(i => i % 2 === 0), 1, ); assertEquals( Lazy.from([1, 2, 3]).count(i => i % 2 === 0), 1, ); assertEquals( Lazy.from([1, 2, 3, 4]).count(i => i % 2 === 0), 2, );
// Test iterated array access. assertEquals( Lazy.from([]) .select(v => v * 2) .count(), 0, ); assertEquals( Lazy.from([1]) .select(v => v * 2) .count(), 1, ); assertEquals( Lazy.from([1, 2]) .select(v => v * 2) .count(), 2, ); assertEquals( Lazy.from([1, 2, 3]) .select(v => v * 2) .count(), 3, ); assertEquals( Lazy.from([1, 2, 3, 4]) .select(v => v * 2) .count(), 4, );
assertEquals( Lazy.from([]) .select(v => v + 1) .count(i => i % 2 === 0), 0, ); assertEquals( Lazy.from([1]) .select(v => v + 1) .count(i => i % 2 === 0), 1, ); assertEquals( Lazy.from([1, 2]) .select(v => v + 1) .count(i => i % 2 === 0), 1, ); assertEquals( Lazy.from([1, 2, 3]) .select(v => v + 1) .count(i => i % 2 === 0), 2, ); assertEquals( Lazy.from([1, 2, 3, 4]) .select(v => v + 1) .count(i => i % 2 === 0), 2, );});
test('elementAt', () => { // Test direct array access. let orig = [1, 2, 3, 4, 5]; assertEquals(Lazy.from(orig).elementAt(0), 1); assertEquals(Lazy.from(orig).elementAt(1), 2); assertEquals(Lazy.from(orig).elementAt(2), 3); assertEquals(Lazy.from(orig).elementAt(3), 4); assertEquals(Lazy.from(orig).elementAt(4), 5); assertThrows(() => Lazy.from(orig).elementAt(5));
orig = []; assertThrows(() => Lazy.from(orig).elementAt(0));
// Test iterated array access. orig = [1, 2, 3, 4, 5]; assertEquals( Lazy.from(orig) .select(v => v * 2) .elementAt(0), 2, ); assertEquals( Lazy.from(orig) .select(v => v * 2) .elementAt(1), 4, ); assertEquals( Lazy.from(orig) .select(v => v * 2) .elementAt(2), 6, ); assertEquals( Lazy.from(orig) .select(v => v * 2) .elementAt(3), 8, ); assertEquals( Lazy.from(orig) .select(v => v * 2) .elementAt(4), 10, ); assertThrows(() => Lazy.from(orig) .select(v => v * 2) .elementAt(5), );
orig = []; assertThrows(() => Lazy.from(orig) .select(v => v * 2) .elementAt(0), );});
test('elementAtOrDefault', () => { // Test direct array access. let orig = [1, 2, 3, 4, 5]; assertEquals(Lazy.from(orig).elementAtOrDefault(0, 9), 1); assertEquals(Lazy.from(orig).elementAtOrDefault(1, 9), 2); assertEquals(Lazy.from(orig).elementAtOrDefault(2, 9), 3); assertEquals(Lazy.from(orig).elementAtOrDefault(3, 9), 4); assertEquals(Lazy.from(orig).elementAtOrDefault(4, 9), 5); assertEquals(Lazy.from(orig).elementAtOrDefault(5, 9), 9);
orig = []; assertEquals(Lazy.from(orig).elementAtOrDefault(5, 9), 9);
// Test iterated array access. orig = [1, 2, 3, 4, 5]; assertEquals( Lazy.from(orig) .select(v => v * 2) .elementAtOrDefault(0, 9), 2, ); assertEquals( Lazy.from(orig) .select(v => v * 2) .elementAtOrDefault(1, 9), 4, ); assertEquals( Lazy.from(orig) .select(v => v * 2) .elementAtOrDefault(2, 9), 6, ); assertEquals( Lazy.from(orig) .select(v => v * 2) .elementAtOrDefault(3, 9), 8, ); assertEquals( Lazy.from(orig) .select(v => v * 2) .elementAtOrDefault(4, 9), 10, ); assertEquals( Lazy.from(orig) .select(v => v * 2) .elementAtOrDefault(5, 9), 9, );
orig = []; assertEquals( Lazy.from(orig) .select(v => v * 2) .elementAtOrDefault(0, 9), 9, );
interface TestObj { value: string; key: number; o: { a: string }; } const objs: TestObj[] = [ { key: 0, value: 'a', o: { a: 'z' } }, { key: 1, value: 'b', o: { a: 'y' } }, { key: 2, value: 'c', o: { a: 'x' } }, { key: 3, value: 'd', o: { a: 'w' } }, { key: 4, value: 'e', o: { a: 'v' } }, ]; assertEquals( Lazy.from(objs).elementAtOrDefault(2, { key: 9, value: 'z', o: { a: 'a' }, }), { key: 2, value: 'c', o: { a: 'x' }, }, ); assertEquals( Lazy.from(objs).elementAtOrDefault(10, { key: 9, value: 'z', o: { a: 'b' }, }), { key: 9, value: 'z', o: { a: 'b' }, }, ); assertEquals(Lazy.from(objs).elementAtOrDefault(2, undefined), { key: 2, value: 'c', o: { a: 'x' }, }); assertEquals(Lazy.from(objs).elementAtOrDefault(10, undefined), undefined);});
test('first', () => { // Test direct array access. assertEquals(Lazy.from([1, 2, 3]).first(), 1); assertEquals(Lazy.from([2, 3, 1]).first(), 2); assertEquals(Lazy.from([3, 2, 1]).first(), 3); assertThrows(() => Lazy.from([]).first());
assertEquals( Lazy.from([1, 2, 3]).first(i => i % 2 === 0), 2, ); assertEquals( Lazy.from([2, 3, 1]).first(i => i % 2 === 0), 2, ); assertEquals( Lazy.from([3, 2, 1]).first(i => i % 2 === 0), 2, ); assertThrows(() => Lazy.from([]).first(i => i % 2 === 0));
// Test iterated array access. assertEquals( Lazy.from([1, 2, 3]) .select(v => v * 2) .first(), 2, ); assertEquals( Lazy.from([2, 3, 1]) .select(v => v * 2) .first(), 4, ); assertEquals( Lazy.from([3, 2, 1]) .select(v => v * 2) .first(), 6, ); assertThrows(() => Lazy.from([]) .select(v => v * 2) .first(), );
assertEquals( Lazy.from([1, 2, 3]) .select(v => v * 2) .first(i => i % 3 === 0), 6, ); assertEquals( Lazy.from([2, 3, 1]) .select(v => v * 2) .first(i => i % 3 === 0), 6, ); assertEquals( Lazy.from([3, 2, 1]) .select(v => v * 2) .first(i => i % 3 === 0), 6, ); assertThrows(() => Lazy.from([]) .select(v => v * 2) .first(i => i % 3 === 0), );});
test('firstOrDefault', () => { // Test direct array access. assertEquals(Lazy.from([1, 2, 3]).firstOrDefault(9), 1); assertEquals(Lazy.from([2, 3, 1]).firstOrDefault(9), 2); assertEquals(Lazy.from([3, 2, 1]).firstOrDefault(9), 3); assertEquals(Lazy.from<number>([]).firstOrDefault(9), 9);
assertEquals( Lazy.from([1, 2, 3]).firstOrDefault(9, i => i % 2 === 0), 2, ); assertEquals( Lazy.from([2, 3, 1]).firstOrDefault(9, i => i % 2 === 0), 2, ); assertEquals( Lazy.from([3, 2, 1]).firstOrDefault(9, i => i % 2 === 0), 2, ); assertEquals( Lazy.from<number>([]).firstOrDefault(9, i => i % 2 === 0), 9, );
// Test iterated array access. assertEquals( Lazy.from([1, 2, 3]) .select(v => v * 2) .firstOrDefault(9), 2, ); assertEquals( Lazy.from([2, 3, 1]) .select(v => v * 2) .firstOrDefault(9), 4, ); assertEquals( Lazy.from([3, 2, 1]) .select(v => v * 2) .firstOrDefault(9), 6, ); assertEquals( Lazy.from<number>([]) .select(v => v * 2) .firstOrDefault(9), 9, );
assertEquals( Lazy.from([1, 2, 3]) .select(v => v * 2) .firstOrDefault(9, i => i % 3 === 0), 6, ); assertEquals( Lazy.from([2, 3, 1]) .select(v => v * 2) .firstOrDefault(9, i => i % 3 === 0), 6, ); assertEquals( Lazy.from([3, 2, 1]) .select(v => v * 2) .firstOrDefault(9, i => i % 3 === 0), 6, ); assertEquals( Lazy.from<number>([]) .select(v => v * 2) .firstOrDefault(9, i => i % 3 === 0), 9, );
assertEquals( Lazy.from([1, 2, 3]).firstOrDefault(undefined, i => i >= 4), undefined, );});
test('forEach', () => { const items: Array<{ v: number; i: number }> = []; Lazy.from([1, 2, 3, 4, 5]).forEach((v, i) => items.push({ v, i })); assertEquals(items, [ { v: 1, i: 0 }, { v: 2, i: 1 }, { v: 3, i: 2 }, { v: 4, i: 3 }, { v: 5, i: 4 }, ]);});
test('iterableEquals', () => { assertEquals(Lazy.from([1]).iterableEquals([1]), true); assertEquals(Lazy.from([1, 2]).iterableEquals([1, 2]), true); assertEquals(Lazy.from([1, 2, 3]).iterableEquals([1, 2, 3]), true); assertEquals(Lazy.from([1, 2, 3, 4]).iterableEquals([1, 2, 3, 4]), true); assertEquals( Lazy.from([1, 2, 3, 4, 5]).iterableEquals([1, 2, 3, 4, 5]), true, ); assertEquals( Lazy.from([1, 2, 3, 4, 5]).iterableEquals([5, 4, 3, 2, 1]), false, ); assertEquals(Lazy.from([1, 2, 3, 4, 5]).iterableEquals([1, 2, 3, 4]), false); assertEquals( Lazy.from([{ value: 1 }, { value: 2 }, { value: 3 }]).iterableEquals( [{ value: 1 }, { value: 2 }, { value: 3 }], (a, b) => a.value === b.value, ), true, );});
test('last', () => { // Test direct array access. assertEquals(Lazy.from([1]).last(), 1); assertEquals(Lazy.from([1, 2]).last(), 2); assertEquals(Lazy.from([1, 2, 3]).last(), 3); assertEquals(Lazy.from([1, 2, 3, 4]).last(), 4); assertEquals(Lazy.from([1, 2, 3, 4, 5]).last(), 5); assertThrows(() => Lazy.from([]).last());
assertThrows(() => Lazy.from([1]).last(i => i % 2 === 0)); assertEquals( Lazy.from([1, 2]).last(i => i % 2 === 0), 2, ); assertEquals( Lazy.from([1, 2, 3]).last(i => i % 2 === 0), 2, ); assertEquals( Lazy.from([1, 2, 3, 4]).last(i => i % 2 === 0), 4, ); assertEquals( Lazy.from([1, 2, 3, 4, 5]).last(i => i % 2 === 0), 4, ); assertThrows(() => Lazy.from([]).last(i => i % 2 === 0));
// Test iterated array access. assertEquals( Lazy.from([1]) .select(v => v * 2) .last(), 2, ); assertEquals( Lazy.from([1, 2]) .select(v => v * 2) .last(), 4, ); assertEquals( Lazy.from([1, 2, 3]) .select(v => v * 2) .last(), 6, ); assertEquals( Lazy.from([1, 2, 3, 4]) .select(v => v * 2) .last(), 8, ); assertEquals( Lazy.from([1, 2, 3, 4, 5]) .select(v => v * 2) .last(), 10, ); assertThrows(() => Lazy.from([]) .select(v => v * 2) .last(), );
assertThrows(() => Lazy.from([1]) .select(v => v * 2) .last(i => i % 3 === 0), ); assertThrows(() => Lazy.from([1, 2]) .select(v => v * 2) .last(i => i % 3 === 0), ); assertEquals( Lazy.from([1, 2, 3]) .select(v => v * 2) .last(i => i % 3 === 0), 6, ); assertEquals( Lazy.from([1, 2, 3, 4]) .select(v => v * 2) .last(i => i % 3 === 0), 6, ); assertEquals( Lazy.from([1, 2, 3, 4, 5]) .select(v => v * 2) .last(i => i % 3 === 0), 6, ); assertThrows(() => Lazy.from([]) .select(v => v * 2) .last(i => i % 3 === 0), );});
test('lastOrDefault', () => { // Test direct array access. assertEquals(Lazy.from([1]).lastOrDefault(9), 1); assertEquals(Lazy.from([1, 2]).lastOrDefault(9), 2); assertEquals(Lazy.from([1, 2, 3]).lastOrDefault(9), 3); assertEquals(Lazy.from([1, 2, 3, 4]).lastOrDefault(9), 4); assertEquals(Lazy.from([1, 2, 3, 4, 5]).lastOrDefault(9), 5); assertEquals(Lazy.from<number>([]).lastOrDefault(9), 9);
assertEquals( Lazy.from([1]).lastOrDefault(9, i => i % 2 === 0), 9, ); assertEquals( Lazy.from([1, 2]).lastOrDefault(9, i => i % 2 === 0), 2, ); assertEquals( Lazy.from([1, 2, 3]).lastOrDefault(9, i => i % 2 === 0), 2, ); assertEquals( Lazy.from([1, 2, 3, 4]).lastOrDefault(9, i => i % 2 === 0), 4, ); assertEquals( Lazy.from([1, 2, 3, 4, 5]).lastOrDefault(9, i => i % 2 === 0), 4, ); assertEquals( Lazy.from<number>([]).lastOrDefault(9, i => i % 2 === 0), 9, );
// Test iterated array access. assertEquals( Lazy.from([1]) .select(v => v * 2) .lastOrDefault(9), 2, ); assertEquals( Lazy.from([1, 2]) .select(v => v * 2) .lastOrDefault(9), 4, ); assertEquals( Lazy.from([1, 2, 3]) .select(v => v * 2) .lastOrDefault(9), 6, ); assertEquals( Lazy.from([1, 2, 3, 4]) .select(v => v * 2) .lastOrDefault(9), 8, ); assertEquals( Lazy.from([1, 2, 3, 4, 5]) .select(v => v * 2) .lastOrDefault(9), 10, ); assertEquals( Lazy.from<number>([]) .select(v => v * 2) .lastOrDefault(9), 9, );
assertEquals( Lazy.from([1]) .select(v => v * 2) .lastOrDefault(9, i => i % 3 === 0), 9, ); assertEquals( Lazy.from([1, 2]) .select(v => v * 2) .lastOrDefault(9, i => i % 3 === 0), 9, ); assertEquals( Lazy.from([1, 2, 3]) .select(v => v * 2) .lastOrDefault(9, i => i % 3 === 0), 6, ); assertEquals( Lazy.from([1, 2, 3, 4]) .select(v => v * 2) .lastOrDefault(9, i => i % 3 === 0), 6, ); assertEquals( Lazy.from([1, 2, 3, 4, 5]) .select(v => v * 2) .lastOrDefault(9, i => i % 3 === 0), 6, ); assertEquals( Lazy.from<number>([]) .select(v => v * 2) .lastOrDefault(9, i => i % 3 === 0), 9, );
assertEquals( Lazy.from([1, 2, 3]).lastOrDefault(undefined, i => i >= 4), undefined, );});
test('max', () => { assertEquals(Lazy.from([1, 2, 3, 4, 5]).max(), 5); assertEquals(Lazy.from([1, 2, 3, 4]).max(), 4); assertEquals(Lazy.from([1, 2, 3]).max(), 3); assertEquals(Lazy.from([1, 2]).max(), 2); assertEquals(Lazy.from([1]).max(), 1); assertThrows(() => Lazy.from([true]).max());
const objs = [ { value: 1 }, { value: 2 }, { value: 3 }, { value: 4 }, { value: 5 }, ]; assertEquals( Lazy.from(objs).max(o => o.value), 5, );});
test('min', () => { assertEquals(Lazy.from([1, 2, 3, 4, 5]).min(), 1); assertEquals(Lazy.from([2, 3, 4, 5]).min(), 2); assertEquals(Lazy.from([3, 4, 5]).min(), 3); assertEquals(Lazy.from([4, 5]).min(), 4); assertEquals(Lazy.from([5]).min(), 5); assertThrows(() => Lazy.from([true]).min());
const objs = [ { value: 1 }, { value: 2 }, { value: 3 }, { value: 4 }, { value: 5 }, ]; assertEquals( Lazy.from(objs).min(o => o.value), 1, );});
test('resolveAll', async () => { const orig = [ Promise.resolve(1), Promise.resolve(2), Promise.resolve(3), Promise.resolve(4), Promise.resolve(5), ]; assertEquals((await Lazy.from(orig).resolveAll()).toArray(), [1, 2, 3, 4, 5]); assertEquals( (await Lazy.from(orig).resolveAll()).select(i => i * 2).toArray(), [2, 4, 6, 8, 10], );
const mix = [ Promise.resolve(1), Promise.resolve(2), Promise.resolve(3), 4, 5, ]; assertEquals((await Lazy.from(mix).resolveAll()).toArray(), [1, 2, 3, 4, 5]); assertEquals( (await Lazy.from(mix).resolveAll()).select(i => i * 2).toArray(), [2, 4, 6, 8, 10], );});
test('single', () => { const orig = [ { key: 1, value: 'a' }, { key: 2, value: 'b' }, { key: 3, value: 'c' }, ]; assertEquals( Lazy.from(orig).single(v => v.key === 1), { key: 1, value: 'a', }, ); assertEquals( Lazy.from(orig).single(v => v.key === 2), { key: 2, value: 'b', }, ); assertEquals( Lazy.from(orig).single(v => v.key === 3), { key: 3, value: 'c', }, ); assertThrows(() => Lazy.from(orig).single(v => v.key === 4));});
test('singleOrDefault', () => { const orig = [ { key: 1, value: 'a' }, { key: 2, value: 'b' }, { key: 3, value: 'c' }, ]; assertEquals( Lazy.from(orig).singleOrDefault(v => v.key === 1, { key: 9, value: 'i' }), { key: 1, value: 'a' }, ); assertEquals( Lazy.from(orig).singleOrDefault(v => v.key === 2, { key: 9, value: 'i' }), { key: 2, value: 'b' }, ); assertEquals( Lazy.from(orig).singleOrDefault(v => v.key === 3, { key: 9, value: 'i' }), { key: 3, value: 'c' }, ); assertEquals( Lazy.from(orig).singleOrDefault(v => v.key === 8, { key: 9, value: 'i' }), { key: 9, value: 'i' }, );
assertEquals( Lazy.from([1, 2, 3]).singleOrDefault(i => i >= 4, undefined), undefined, );});
test('stringJoin', () => { assertEquals(Lazy.from([]).stringJoin(), ''); assertEquals(Lazy.from([1]).stringJoin(), '1'); assertEquals(Lazy.from([1, 2]).stringJoin(), '12'); assertEquals(Lazy.from([1, 2, 3]).stringJoin(), '123'); assertEquals(Lazy.from([1, 2, 3, 4]).stringJoin(), '1234');
assertEquals(Lazy.from([]).stringJoin(','), ''); assertEquals(Lazy.from([1]).stringJoin(','), '1'); assertEquals(Lazy.from([1, 2]).stringJoin(','), '1,2'); assertEquals(Lazy.from([1, 2, 3]).stringJoin(','), '1,2,3'); assertEquals(Lazy.from([1, 2, 3, 4]).stringJoin(','), '1,2,3,4');
assertEquals( Lazy.from([]).stringJoin(',', i => `${i * 2}`), '', ); assertEquals( Lazy.from([1]).stringJoin(',', i => `${i * 2}`), '2', ); assertEquals( Lazy.from([1, 2]).stringJoin(',', i => `${i * 2}`), '2,4', ); assertEquals( Lazy.from([1, 2, 3]).stringJoin(',', i => `${i * 2}`), '2,4,6', ); assertEquals( Lazy.from([1, 2, 3, 4]).stringJoin(',', i => `${i * 2}`), '2,4,6,8', );});
test('sum', () => { assertEquals(Lazy.from([1]).sum(), 1); assertEquals(Lazy.from([1, 2]).sum(), 3); assertEquals(Lazy.from([1, 2, 3]).sum(), 6); assertEquals(Lazy.from([1, 2, 3, 4]).sum(), 10); assertEquals(Lazy.from([1, 2, 3, 4, 5]).sum(), 15); assertThrows(() => Lazy.from([true]).sum());
const objs = [ { value: 1 }, { value: 2 }, { value: 3 }, { value: 4 }, { value: 5 }, ]; assertEquals( Lazy.from(objs).sum(o => o.value), 15, );});
test('toJSON', () => { const s = JSON.stringify;
assertEquals(s(Lazy.from([1, 2, 3, 4, 5])), s([1, 2, 3, 4, 5])); assertEquals( s(Lazy.from([1, 2, 3, 4, 5]).select(i => i * 2)), s([2, 4, 6, 8, 10]), ); assertEquals(s(Lazy.from([1, 2, 3, 4, 5]).reverse()), s([5, 4, 3, 2, 1])); assertEquals( s(Lazy.from([1, 2, 3, 4, 5]).where(i => i % 2 === 0)), s([2, 4]), );});
test('toMap', () => { const orig = [ { key: 1, value: 'a' }, { key: 2, value: 'b' }, { key: 3, value: 'c' }, { key: 4, value: 'd' }, { key: 5, value: 'e' }, ];
const map1 = new Map<number, string>( orig.map<[number, string]>(v => [v.key, v.value]), ); for (const [key, value] of Lazy.from(orig).toMap( v => v.key, v => v.value, )) { assert(map1.has(key)); assertEquals(map1.get(key), value); }
const map2 = new Map<number, { key: number; value: string }>( orig.map<[number, { key: number; value: string }]>(v => [v.key, v]), ); for (const [key, value] of Lazy.from(orig).toMap( v => v.key, v => v, )) { assert(map2.has(key)); assertEquals(map2.get(key), value); }});