amp/test/Future/FutureTest.php

<?php

namespace Amp\Test\Future;

use Amp\Deferred;
use Amp\Future;
use PHPUnit\Framework\TestCase;
use Revolt\EventLoop\Loop;
use function Amp\Future\spawn;
use function Revolt\EventLoop\delay;

class FutureTest extends TestCase
{
    public function testIterate(): void
    {
        $this->expectOutputString('a=1 b=0 c=2 ');

        $a = $this->delay(0.1, 'a');
        $b = $this->delay(0.2, 'b');
        $c = $this->delay(0.3, 'c');

        foreach (Future::iterate([$b, $a, $c]) as $index => $future) {
            print $future->join() . '=' . $index . ' ';
        }
    }

    public function testIterateGenerator(): void
    {
        $this->expectOutputString('a=1 ');

        /**
         * @var \Generator<int, Future<string>, void, void>
         */
        $iterator = (function () {
            yield (new Deferred)->getFuture();
            yield $this->delay(0.1, 'a');

            // Never joins
            (new Deferred)->getFuture()->join();
        })();

        foreach (Future::iterate($iterator) as $index => $future) {
            print $future->join() . '=' . $index . ' ';
            break;
        }
    }

    public function testComplete(): void
    {
        $deferred = new Deferred;
        $future = $deferred->getFuture();

        $deferred->complete('result');

        self::assertSame('result', $future->join());
    }

    public function testCompleteAsync(): void
    {
        $deferred = new Deferred;
        $future = $deferred->getFuture();

        Loop::delay(0.01, fn() => $deferred->complete('result'));

        self::assertSame('result', $future->join());
    }

    public function testCompleteImmediate(): void
    {
        $future = Future::complete('result');

        self::assertSame('result', $future->join());
    }

    public function testError(): void
    {
        $deferred = new Deferred;
        $future = $deferred->getFuture();

        $deferred->error(new \Exception('foo'));

        $this->expectException(\Exception::class);
        $this->expectExceptionMessage('foo');

        $future->join();
    }

    public function testErrorAsync(): void
    {
        $deferred = new Deferred;
        $future = $deferred->getFuture();

        Loop::delay(0.01, fn() => $deferred->error(new \Exception('foo')));

        $this->expectException(\Exception::class);
        $this->expectExceptionMessage('foo');

        $future->join();
    }

    public function testErrorImmediate(): void
    {
        $future = Future::error(new \Exception('foo'));

        $this->expectException(\Exception::class);
        $this->expectExceptionMessage('foo');

        $future->join();
    }

    public function testCompleteWithFuture(): void
    {
        $deferred = new Deferred;

        $this->expectException(\Error::class);
        $this->expectExceptionMessage('Cannot complete with an instance of');

        $deferred->complete(Future::complete(null));
    }

    /**
     * @template T
     *
     * @param float $seconds
     * @param T $value
     *
     * @return Future<T>
     */
    private function delay(float $seconds, mixed $value): Future
    {
        return spawn(
            /**
             * @return T
             */
            static function () use ($seconds, $value) {
                delay($seconds);

                return $value;
            }
        );
    }
}