tez-utils-enum/tests/StepTraitTest.php

<?php

declare(strict_types=1);

namespace Tez\Utils\Tests\Enum;

use PHPUnit\Framework\TestCase;
use Tez\Utils\Enum\EnumTrait;
use Tez\Utils\Enum\StepTrait;

enum OrderStatus
{
    use EnumTrait;
    use StepTrait;

    case Draft;
    case Pending;
    case Shipped;
    case Delivered;
    case Cancelled;
}

final class StepTraitTest extends TestCase
{
    // -------------------------------------------------------------------------
    // next()
    // -------------------------------------------------------------------------

    public function testNextReturnsFollowingCase(): void
    {
        self::assertSame(OrderStatus::Shipped, OrderStatus::Pending->next());
    }

    public function testNextFromFirstReturnsSecond(): void
    {
        self::assertSame(OrderStatus::Pending, OrderStatus::Draft->next());
    }

    public function testNextFromLastReturnsNull(): void
    {
        self::assertNull(OrderStatus::Cancelled->next());
    }

    public function testNextFromSecondToLastReturnsLast(): void
    {
        self::assertSame(OrderStatus::Cancelled, OrderStatus::Delivered->next());
    }

    // -------------------------------------------------------------------------
    // prev()
    // -------------------------------------------------------------------------

    public function testPrevReturnsPrecedingCase(): void
    {
        self::assertSame(OrderStatus::Draft, OrderStatus::Pending->prev());
    }

    public function testPrevFromLastReturnsPenultimate(): void
    {
        self::assertSame(OrderStatus::Delivered, OrderStatus::Cancelled->prev());
    }

    public function testPrevFromFirstReturnsNull(): void
    {
        self::assertNull(OrderStatus::Draft->prev());
    }

    public function testPrevFromSecondReturnsFirst(): void
    {
        self::assertSame(OrderStatus::Draft, OrderStatus::Pending->prev());
    }

    // -------------------------------------------------------------------------
    // Chaining
    // -------------------------------------------------------------------------

    public function testNextThenPrevReturnsSameCase(): void
    {
        $case = OrderStatus::Pending;

        self::assertSame($case, $case->next()?->prev());
    }

    public function testPrevThenNextReturnsSameCase(): void
    {
        $case = OrderStatus::Shipped;

        self::assertSame($case, $case->prev()?->next());
    }

    // -------------------------------------------------------------------------
    // Single-case enum edge case
    // -------------------------------------------------------------------------

    public function testNextAndPrevReturnNullForOnlyCase(): void
    {
        self::assertNull(Alone::Only->next());
        self::assertNull(Alone::Only->prev());
    }
}

enum Alone
{
    use StepTrait;

    case Only;
}