Tests\Innmind\Immutable\Sequence\LazyTest

Complexity

Total Complexity

54

Size/Duplication

Total Lines	818
Duplicated Lines	0 %

Importance

Changes	3
Bugs	1	Features	1

46 Methods

Rating	Name	Duplication	Size	Complexity
A	testForeach()	0	20	1
A	testReturnNothingWhenTryingToAccessLastElementOnEmptySequence()	0	12	2
A	testSequenceNotCompletelyLoadedWhenTakingFewerThanItsSize()	0	15	1
A	testSize()	0	9	1
A	testCallCleanupWhenIndexOfElementBeingLookedForIsFoundBeforeTheEndOfGenerator()	0	20	1
A	testEquals()	0	14	1
A	testCallCleanupWhenElementBeingLookedForIsFoundBeforeTheEndOfGenerator()	0	16	1
A	testIndices()	0	15	1
A	testContains()	0	10	1
A	testFind()	0	41	1
A	testGeneratorNotLoadedAtInstanciation()	0	9	1
A	testClear()	0	15	1
A	testReturnNothingWhenTryingToAccessIndexOfUnknownValue()	0	12	2
A	testCallCleanupWhenGettingIndexBeforeTheEndOfGenerator()	0	20	1
A	testIndexOf()	0	20	1
A	testTakeEnd()	0	12	1
A	testMap()	0	16	1
A	testCallCleanupWhenFindingElementBeforeTheEndOfGenerator()	0	20	1
A	testReverse()	0	17	1
A	testIndicesOnEmptySequence()	0	12	2
A	testDiff()	0	24	1
A	testFirst()	0	13	1
A	testSort()	0	13	2
A	testGroupBy()	0	15	1
A	testDrop()	0	17	1
A	testIntersect()	0	24	1
A	testGet()	0	9	1
A	testSlice()	0	17	1
A	testDistinct()	0	16	1
A	testDropEnd()	0	13	1
A	testAdd()	0	14	1
A	testPartition()	0	15	1
A	testReturnNothingWhenIndexNotFound()	0	12	2
A	testAppend()	0	24	1
A	get()	0	5	1
A	testReturnNothingWhenTryingToAccessFirstElementOnEmptySequence()	0	12	2
A	testPad()	0	18	1
A	testCallCleanupWhenTakingLessElementsThanContainedInTheGenerator()	0	16	1
A	testGroupEmptySequence()	0	12	2
A	testEmpty()	0	21	2
A	testInterface()	0	5	1
A	testReduce()	0	10	1
A	testIterator()	0	11	1
A	testTake()	0	16	1
A	testLast()	0	13	1
A	testFilter()	0	17	1

<?php
declare(strict_types = 1);

namespace Tests\Innmind\Immutable\Sequence;

use Innmind\Immutable\{
    Sequence\Lazy,
    Sequence\Implementation,
    Map,
    Sequence,
    Str,
    Set,
    SideEffect,
};
use PHPUnit\Framework\TestCase;

class LazyTest extends TestCase
{
    public function testInterface()
    {
        $this->assertInstanceOf(
            Implementation::class,
            new Lazy(static fn() => yield),
        );
    }

    public function testGeneratorNotLoadedAtInstanciation()
    {
        $loaded = false;
        $sequence = new Lazy(static function() use (&$loaded) {

The assignment to $sequence is dead and can be removed.

            yield 1;
            $loaded = true;
        });

        $this->assertFalse($loaded);
    }

    public function testSize()
    {
        $sequence = new Lazy(static function() {
            yield 1;
            yield 1;
        });

        $this->assertSame(2, $sequence->size());
        $this->assertSame(2, $sequence->count());
    }

    public function testIterator()
    {
        $sequence = new Lazy(static function() {
            yield 1;
            yield 2;
            yield 3;
        });

        $this->assertSame(
            [1, 2, 3],
            \iterator_to_array($sequence->iterator()),
        );
    }

    public function testGet()
    {
        $sequence = new Lazy(static function() {
            yield 1;
            yield 42;
            yield 3;
        });

        $this->assertSame(42, $this->get($sequence, 1));
    }

    public function testReturnNothingWhenIndexNotFound()
    {
        $sequence = new Lazy(static function() {
            if (false) {
                yield 1;
            }
        });

        $this->assertNull(
            $sequence->get(0)->match(
                static fn($value) => $value,
                static fn() => null,
            ),
        );
    }

    public function testDiff()
    {
        $aLoaded = false;
        $bLoaded = false;
        $a = new Lazy(static function() use (&$aLoaded) {
            yield 1;
            yield 2;
            $aLoaded = true;
        });
        $b = new Lazy(static function() use (&$bLoaded) {
            yield 2;
            yield 3;
            $bLoaded = true;
        });
        $c = $a->diff($b);

        $this->assertFalse($aLoaded);
        $this->assertFalse($bLoaded);
        $this->assertSame([1, 2], \iterator_to_array($a->iterator()));
        $this->assertSame([2, 3], \iterator_to_array($b->iterator()));
        $this->assertInstanceOf(Lazy::class, $c);
        $this->assertSame([1], \iterator_to_array($c->iterator()));
        $this->assertTrue($aLoaded);
        $this->assertTrue($bLoaded);
    }

    public function testDistinct()
    {
        $loaded = false;
        $a = new Lazy(static function() use (&$loaded) {
            yield 1;
            yield 2;
            yield 1;
            $loaded = true;
        });
        $b = $a->distinct();

        $this->assertFalse($loaded);
        $this->assertSame([1, 2, 1], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Lazy::class, $b);
        $this->assertSame([1, 2], \iterator_to_array($b->iterator()));
        $this->assertTrue($loaded);
    }

    public function testDrop()
    {
        $loaded = false;
        $a = new Lazy(static function() use (&$loaded) {
            yield 1;
            yield 2;
            yield 3;
            yield 4;
            $loaded = true;
        });
        $b = $a->drop(2);

        $this->assertFalse($loaded);
        $this->assertSame([1, 2, 3, 4], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Lazy::class, $b);
        $this->assertSame([3, 4], \iterator_to_array($b->iterator()));
        $this->assertTrue($loaded);
    }

    public function testDropEnd()
    {
        $a = new Lazy(static function() {
            yield 1;
            yield 2;
            yield 3;
            yield 4;
        });
        $b = $a->dropEnd(2);

        $this->assertSame([1, 2, 3, 4], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Implementation::class, $b);
        $this->assertSame([1, 2], \iterator_to_array($b->iterator()));
    }

    public function testEquals()
    {
        $a = new Lazy(static function() {
            yield 1;
            yield 2;
        });
        $b = new Lazy(static function() {
            yield 1;
            yield 2;
            yield 3;
        });

        $this->assertTrue($a->equals($a));
        $this->assertFalse($a->equals($b));
    }

    public function testFilter()
    {
        $loaded = false;
        $a = new Lazy(static function() use (&$loaded) {
            yield 1;
            yield 2;
            yield 3;
            yield 4;
            $loaded = true;
        });
        $b = $a->filter(static fn($i) => $i % 2 === 0);

        $this->assertFalse($loaded);
        $this->assertSame([1, 2, 3, 4], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Lazy::class, $b);
        $this->assertSame([2, 4], \iterator_to_array($b->iterator()));
        $this->assertTrue($loaded);
    }

    public function testForeach()
    {
        $sequence = new Lazy(static function() {
            yield 1;
            yield 2;
            yield 3;
            yield 4;
        });
        $calls = 0;
        $sum = 0;

        $this->assertInstanceOf(
            SideEffect::class,
            $sequence->foreach(static function($i) use (&$calls, &$sum) {
                ++$calls;
                $sum += $i;
            }),
        );
        $this->assertSame(4, $calls);
        $this->assertSame(10, $sum);
    }

    public function testGroupEmptySequence()
    {
        $sequence = new Lazy(static function() {
            if (false) {
                yield 1;
            }
        });

        $this->assertTrue(
            $sequence
                ->groupBy(static fn($i) => $i)
                ->equals(Map::of()),
        );
    }

    public function testGroupBy()
    {
        $sequence = new Lazy(static function() {
            yield 1;
            yield 2;
            yield 3;
            yield 4;
        });
        $groups = $sequence->groupBy(static fn($i) => $i % 2);

        $this->assertSame([1, 2, 3, 4], \iterator_to_array($sequence->iterator()));
        $this->assertInstanceOf(Map::class, $groups);
        $this->assertCount(2, $groups);
        $this->assertSame([2, 4], $this->get($groups, 0)->toList());
        $this->assertSame([1, 3], $this->get($groups, 1)->toList());
    }

    public function testReturnNothingWhenTryingToAccessFirstElementOnEmptySequence()
    {
        $sequence = new Lazy(static function() {
            if (false) {
                yield 1;
            }
        });

        $this->assertNull(
            $sequence->first()->match(
                static fn($value) => $value,
                static fn() => null,
            ),
        );
    }

    public function testReturnNothingWhenTryingToAccessLastElementOnEmptySequence()
    {
        $sequence = new Lazy(static function() {
            if (false) {
                yield 1;
            }
        });

        $this->assertNull(
            $sequence->last()->match(
                static fn($value) => $value,
                static fn() => null,
            ),
        );
    }

    public function testFirst()
    {
        $sequence = new Lazy(static function() {
            yield 2;
            yield 3;
            yield 4;
        });

        $this->assertSame(
            2,
            $sequence->first()->match(
                static fn($value) => $value,
                static fn() => null,
            ),
        );
    }

    public function testLast()
    {
        $sequence = new Lazy(static function() {
            yield 1;
            yield 2;
            yield 3;
        });

        $this->assertSame(
            3,
            $sequence->last()->match(
                static fn($value) => $value,
                static fn() => null,
            ),
        );
    }

    public function testContains()
    {
        $sequence = new Lazy(static function() {
            yield 1;
            yield 2;
            yield 3;
        });

        $this->assertTrue($sequence->contains(2));

2 of type integer is incompatible with the type Innmind\Immutable\Sequence\T expected by parameter $element of Innmind\Immutable\Sequence\Lazy::contains().

        $this->assertFalse($sequence->contains(4));
    }

    public function testIndexOf()
    {
        $sequence = new Lazy(static function() {
            yield 1;
            yield 2;
            yield 4;
        });

        $this->assertSame(
            1,
            $sequence->indexOf(2)->match(

2 of type integer is incompatible with the type Innmind\Immutable\Sequence\T expected by parameter $element of Innmind\Immutable\Sequence\Lazy::indexOf().

                static fn($value) => $value,
                static fn() => null,
            ),
        );
        $this->assertSame(
            2,
            $sequence->indexOf(4)->match(
                static fn($value) => $value,
                static fn() => null,
            ),
        );
    }

    public function testReturnNothingWhenTryingToAccessIndexOfUnknownValue()
    {
        $sequence = new Lazy(static function() {
            if (false) {
                yield 1;
            }
        });

        $this->assertNull(
            $sequence->indexOf(1)->match(

1 of type integer is incompatible with the type Innmind\Immutable\Sequence\T expected by parameter $element of Innmind\Immutable\Sequence\Lazy::indexOf().

                static fn($value) => $value,
                static fn() => null,
            ),
        );
    }

    public function testIndices()
    {
        $loaded = false;
        $a = new Lazy(static function() use (&$loaded) {
            yield '1';
            yield '2';
            $loaded = true;
        });
        $b = $a->indices();

        $this->assertFalse($loaded);
        $this->assertSame(['1', '2'], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Lazy::class, $b);
        $this->assertSame([0, 1], \iterator_to_array($b->iterator()));
        $this->assertTrue($loaded);
    }

    public function testIndicesOnEmptySequence()
    {
        $a = new Lazy(static function() {
            if (false) {
                yield 1;
            }
        });
        $b = $a->indices();

        $this->assertSame([], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Lazy::class, $b);
        $this->assertSame([], \iterator_to_array($b->iterator()));
    }

    public function testMap()
    {
        $loaded = false;
        $a = new Lazy(static function() use (&$loaded) {
            yield 1;
            yield 2;
            yield 3;
            $loaded = true;
        });
        $b = $a->map(static fn($i) => $i * 2);

        $this->assertFalse($loaded);
        $this->assertSame([1, 2, 3], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Lazy::class, $b);
        $this->assertSame([2, 4, 6], \iterator_to_array($b->iterator()));
        $this->assertTrue($loaded);
    }

    public function testPad()
    {
        $loaded = false;
        $a = new Lazy(static function() use (&$loaded) {
            yield 1;
            yield 2;
            $loaded = true;
        });
        $b = $a->pad(4, 0);

0 of type integer is incompatible with the type Innmind\Immutable\Sequence\T expected by parameter $element of Innmind\Immutable\Sequence\Lazy::pad().

        $c = $a->pad(1, 0);

        $this->assertFalse($loaded);
        $this->assertSame([1, 2], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Lazy::class, $b);
        $this->assertInstanceOf(Lazy::class, $c);
        $this->assertSame([1, 2, 0, 0], \iterator_to_array($b->iterator()));
        $this->assertSame([1, 2], \iterator_to_array($c->iterator()));
        $this->assertTrue($loaded);
    }

    public function testPartition()
    {
        $sequence = new Lazy(static function() {
            yield 1;
            yield 2;
            yield 3;
            yield 4;
        });
        $partition = $sequence->partition(static fn($i) => $i % 2 === 0);

        $this->assertSame([1, 2, 3, 4], \iterator_to_array($sequence->iterator()));
        $this->assertInstanceOf(Map::class, $partition);
        $this->assertCount(2, $partition);
        $this->assertSame([2, 4], $this->get($partition, true)->toList());
        $this->assertSame([1, 3], $this->get($partition, false)->toList());
    }

    public function testSlice()
    {
        $loaded = false;
        $a = new Lazy(static function() use (&$loaded) {
            yield 2;
            yield 3;
            yield 4;
            yield 5;
            $loaded = true;
        });
        $b = $a->slice(1, 3);

        $this->assertFalse($loaded);
        $this->assertSame([2, 3, 4, 5], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Lazy::class, $b);
        $this->assertSame([3, 4], \iterator_to_array($b->iterator()));
        $this->assertTrue($loaded);
    }

    public function testTake()
    {
        $loaded = false;
        $a = new Lazy(static function() use (&$loaded) {
            yield 2;
            yield 3;
            yield 4;
            $loaded = true;
        });
        $b = $a->take(2);

        $this->assertFalse($loaded);
        $this->assertSame([2, 3, 4], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Lazy::class, $b);
        $this->assertSame([2, 3], \iterator_to_array($b->iterator()));
        $this->assertTrue($loaded);
    }

    public function testSequenceNotCompletelyLoadedWhenTakingFewerThanItsSize()
    {
        $loaded = false;
        $a = new Lazy(static function() use (&$loaded) {
            yield 2;
            yield 3;
            yield 4;
            $loaded = true;
        });
        $b = $a->take(2);

        $this->assertFalse($loaded);
        $this->assertInstanceOf(Lazy::class, $b);
        $this->assertSame([2, 3], \iterator_to_array($b->iterator()));
        $this->assertFalse($loaded);
    }

    public function testTakeEnd()
    {
        $a = new Lazy(static function() {
            yield 2;
            yield 3;
            yield 4;
        });
        $b = $a->takeEnd(2);

        $this->assertSame([2, 3, 4], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Implementation::class, $b);
        $this->assertSame([3, 4], \iterator_to_array($b->iterator()));
    }

    public function testAppend()
    {
        $aLoaded = false;
        $bLoaded = false;
        $a = new Lazy(static function() use (&$aLoaded) {
            yield 1;
            yield 2;
            $aLoaded = true;
        });
        $b = new Lazy(static function() use (&$bLoaded) {
            yield 3;
            yield 4;
            $bLoaded = true;
        });
        $c = $a->append($b);

        $this->assertFalse($aLoaded);
        $this->assertFalse($bLoaded);
        $this->assertSame([1, 2], \iterator_to_array($a->iterator()));
        $this->assertSame([3, 4], \iterator_to_array($b->iterator()));
        $this->assertInstanceOf(Lazy::class, $c);
        $this->assertSame([1, 2, 3, 4], \iterator_to_array($c->iterator()));
        $this->assertTrue($aLoaded);
        $this->assertTrue($bLoaded);
    }

    public function testIntersect()
    {
        $aLoaded = false;
        $bLoaded = false;
        $a = new Lazy(static function() use (&$aLoaded) {
            yield 1;
            yield 2;
            $aLoaded = true;
        });
        $b = new Lazy(static function() use (&$bLoaded) {
            yield 2;
            yield 3;
            $bLoaded = true;
        });
        $c = $a->intersect($b);

        $this->assertFalse($aLoaded);
        $this->assertFalse($bLoaded);
        $this->assertSame([1, 2], \iterator_to_array($a->iterator()));
        $this->assertSame([2, 3], \iterator_to_array($b->iterator()));
        $this->assertInstanceOf(Lazy::class, $c);
        $this->assertSame([2], \iterator_to_array($c->iterator()));
        $this->assertTrue($aLoaded);
        $this->assertTrue($bLoaded);
    }

    public function testAdd()
    {
        $loaded = false;
        $a = new Lazy(static function() use (&$loaded) {
            yield 1;
            $loaded = true;
        });
        $b = ($a)(2);

        $this->assertFalse($loaded);
        $this->assertSame([1], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Lazy::class, $b);
        $this->assertSame([1, 2], \iterator_to_array($b->iterator()));
        $this->assertTrue($loaded);
    }

    public function testSort()
    {
        $a = new Lazy(static function() {
            yield 1;
            yield 4;
            yield 3;
            yield 2;
        });
        $b = $a->sort(static fn($a, $b) => $a > $b ? 1 : -1);

        $this->assertSame([1, 4, 3, 2], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Lazy::class, $b);
        $this->assertSame([1, 2, 3, 4], \iterator_to_array($b->iterator()));
    }

    public function testReduce()
    {
        $sequence = new Lazy(static function() {
            yield 1;
            yield 2;
            yield 3;
            yield 4;
        });

        $this->assertSame(10, $sequence->reduce(0, static fn($sum, $i) => $sum + $i));

0 of type integer is incompatible with the type Innmind\Immutable\Sequence\R expected by parameter $carry of Innmind\Immutable\Sequence\Lazy::reduce().

    }

    public function testClear()
    {
        $loaded = false;
        $a = new Lazy(static function() use (&$loaded) {
            yield 1;
            yield 2;
            $loaded = true;
        });
        $b = $a->clear();

        $this->assertFalse($loaded);
        $this->assertInstanceOf(Implementation::class, $b);
        $this->assertSame([], \iterator_to_array($b->iterator()));
        $this->assertFalse($loaded);
        $this->assertSame([1, 2], \iterator_to_array($a->iterator()));
    }

    public function testReverse()
    {
        $loaded = false;
        $a = new Lazy(static function() use (&$loaded) {
            yield 1;
            yield 2;
            yield 3;
            yield 4;
            $loaded = true;
        });
        $b = $a->reverse();

        $this->assertFalse($loaded);
        $this->assertSame([1, 2, 3, 4], \iterator_to_array($a->iterator()));
        $this->assertInstanceOf(Lazy::class, $b);
        $this->assertSame([4, 3, 2, 1], \iterator_to_array($b->iterator()));
        $this->assertTrue($loaded);
    }

    public function testEmpty()
    {
        $aLoaded = false;
        $bLoaded = false;
        $a = new Lazy(static function() use (&$aLoaded) {
            yield 1;
            $aLoaded = true;
        });
        $b = new Lazy(static function() use (&$bLoaded) {
            if (false) {
                yield 1;
            }
            $bLoaded = true;
        });

        $this->assertFalse($aLoaded);
        $this->assertFalse($bLoaded);
        $this->assertTrue($b->empty());
        $this->assertFalse($a->empty());
        $this->assertFalse($aLoaded); // still false as we don't need to load the full iterator to know if it's empty
        $this->assertTrue($bLoaded);
    }

    public function testFind()
    {
        $count = 0;
        $sequence = new Lazy(static function() use (&$count) {
            ++$count;
            yield 1;
            ++$count;
            yield 2;
            ++$count;
            yield 3;
        });

        $this->assertSame(
            1,
            $sequence->find(static fn($i) => $i === 1)->match(
                static fn($i) => $i,
                static fn() => null,
            ),
        );
        $this->assertSame(1, $count);
        $this->assertSame(
            2,
            $sequence->find(static fn($i) => $i === 2)->match(
                static fn($i) => $i,
                static fn() => null,
            ),
        );
        $this->assertSame(3, $count);
        $this->assertSame(
            3,
            $sequence->find(static fn($i) => $i === 3)->match(
                static fn($i) => $i,
                static fn() => null,
            ),
        );
        $this->assertSame(6, $count);

        $this->assertNull(
            $sequence->find(static fn($i) => $i === 0)->match(
                static fn($i) => $i,
                static fn() => null,
            ),
        );
    }

    public function testCallCleanupWhenGettingIndexBeforeTheEndOfGenerator()
    {
        $cleanupCalled = false;
        $sequence = new Lazy(static function($registerCleanup) use (&$cleanupCalled) {
            $registerCleanup(static function() use (&$cleanupCalled) {
                $cleanupCalled = true;
            });
            yield 2;
            yield 3;
            yield 4;
            yield 5;
        });
        $this->assertFalse($cleanupCalled);
        $value = $sequence->get(1)->match(
            static fn($value) => $value,
            static fn() => null,
        );

        $this->assertSame(3, $value);
        $this->assertTrue($cleanupCalled);
    }

    public function testCallCleanupWhenElementBeingLookedForIsFoundBeforeTheEndOfGenerator()
    {
        $cleanupCalled = false;
        $sequence = new Lazy(static function($registerCleanup) use (&$cleanupCalled) {
            $registerCleanup(static function() use (&$cleanupCalled) {
                $cleanupCalled = true;
            });
            yield 2;
            yield 3;
            yield 4;
            yield 5;
        });

        $this->assertFalse($cleanupCalled);
        $this->assertTrue($sequence->contains(3));

3 of type integer is incompatible with the type Innmind\Immutable\Sequence\T expected by parameter $element of Innmind\Immutable\Sequence\Lazy::contains().

        $this->assertTrue($cleanupCalled);
    }

    public function testCallCleanupWhenIndexOfElementBeingLookedForIsFoundBeforeTheEndOfGenerator()
    {
        $cleanupCalled = false;
        $sequence = new Lazy(static function($registerCleanup) use (&$cleanupCalled) {
            $registerCleanup(static function() use (&$cleanupCalled) {
                $cleanupCalled = true;
            });
            yield 2;
            yield 3;
            yield 4;
            yield 5;
        });

        $this->assertFalse($cleanupCalled);
        $index = $sequence->indexOf(3)->match(

3 of type integer is incompatible with the type Innmind\Immutable\Sequence\T expected by parameter $element of Innmind\Immutable\Sequence\Lazy::indexOf().

            static fn($index) => $index,
            static fn() => null,
        );
        $this->assertSame(1, $index);
        $this->assertTrue($cleanupCalled);
    }

    public function testCallCleanupWhenTakingLessElementsThanContainedInTheGenerator()
    {
        $cleanupCalled = false;
        $sequence = new Lazy(static function($registerCleanup) use (&$cleanupCalled) {
            $registerCleanup(static function() use (&$cleanupCalled) {
                $cleanupCalled = true;
            });
            yield 2;
            yield 3;
            yield 4;
            yield 5;
        });

        $this->assertFalse($cleanupCalled);
        $this->assertSame([2, 3], \iterator_to_array($sequence->take(2)->iterator()));
        $this->assertTrue($cleanupCalled);
    }

    public function testCallCleanupWhenFindingElementBeforeTheEndOfGenerator()
    {
        $cleanupCalled = false;
        $sequence = new Lazy(static function($registerCleanup) use (&$cleanupCalled) {
            $registerCleanup(static function() use (&$cleanupCalled) {
                $cleanupCalled = true;
            });
            yield 2;
            yield 3;
            yield 4;
            yield 5;
        });
        $this->assertFalse($cleanupCalled);
        $value = $sequence->find(static fn($value) => $value === 3)->match(
            static fn($value) => $value,
            static fn() => null,
        );

        $this->assertSame(3, $value);
        $this->assertTrue($cleanupCalled);
    }

    public function get($map, $index)
    {
        return $map->get($index)->match(
            static fn($value) => $value,
            static fn() => null,
        );
    }
}