inspired-by-fsharp/tests/Unit/OptionTest.php

<?php
/**
 * @author Daniel J. Summers <daniel@bitbadger.solutions>
 * @license MIT
 */

declare(strict_types=1);

use BitBadger\InspiredByFSharp\Option;
use PhpOption\{None, Some};

describe('->value', function () {
    test('retrieves the value for Some', function () {
        expect(Option::Some(9)->value)->toBe(9);
    });
    test('throws an exception for None', function () {
        expect(fn() => Option::None()->value)->toThrow(InvalidArgumentException::class);
    });
});

describe('->isNone', function () {
    test('returns true for None', function () {
        expect(Option::None()->isNone)->toBeTrue();
    });
    test('returns false for Some', function () {
        expect(Option::Some(8)->isNone)->toBeFalse();
    });
});

describe('->isSome', function () {
    test('returns false for None', function () {
        expect(Option::None()->isSome)->toBeFalse();
    });
    test('returns true for Some', function () {
        expect(Option::Some('boo')->isSome)->toBeTrue();
    });
});

describe('->getOrDefault()', function () {
    test('returns default value for None', function () {
        expect(Option::None()->getOrDefault('yes'))->toBe('yes');
    });
    test('returns option value for Some', function () {
        expect(Option::Some('no')->getOrDefault('yes'))->toBe('no');
    });
});

describe('->getOrCall()', function () {
    test('returns value from callable for None', function () {
        expect(Option::None()->getOrCall(fn() => 'called'))->toBe('called');
    });
    test('returns option value for Some', function () {
        expect(Option::Some('passed')->getOrCall(fn() => 'called'))->toBe('passed');
    });
});

describe('->getOrThrow()', function () {
    test('throws an exception for None', function () {
        expect(fn() => Option::None()->getOrThrow(fn() => throw new BadMethodCallException()))
            ->toThrow(BadMethodCallException::class);
    });
    test('returns option value for Some', function () {
        expect(Option::Some('no throw')->getOrThrow(fn() => throw new BadMethodCallException()))->toBe('no throw');
    });
});

describe('->bind()', function () {
    test('returns None when binding against None', function () {
        $original = Option::None();
        $bound = $original->bind(fn($it) => Option::Some('value'));
        expect($bound)->isNone->toBeTrue()->and($bound)->toBe($original);
    });
    test('returns Some when binding against Some with Some', function () {
        expect(Option::Some('hello')->bind(fn($it) => Option::Some('goodbye')))
            ->isSome->toBeTrue()->value->toBe('goodbye');
    });
    test('returns None when binding against Some with None', function () {
        expect(Option::Some('greetings')->bind(fn($it) => Option::None()))->isNone->toBeTrue();
    });
});

describe('->contains()', function () {
    test('returns false for None', function () {
        expect(Option::None()->contains(null))->toBeFalse();
    });
    test('returns true for Some when strict equality is matched', function () {
        expect(Option::Some(3)->contains(3))->toBeTrue();
    });
    test('returns false for Some when strict equality is not matched', function () {
        expect(Option::Some('3')->contains(3))->toBeFalse();
    });
    test('returns true for Some when loose equality is matched', function () {
        expect(Option::Some('3')->contains(3, strict: false))->toBeTrue();
    });
    test('returns false for Some when loose equality is not matched', function () {
        expect(Option::Some('3')->contains(4, strict: false))->toBeFalse();
    });
});

describe('->exists()', function () {
    test('returns false for None', function () {
        expect(Option::None()->exists(fn($it) => true))->toBeFalse();
    });
    test('returns true for Some and matching condition', function () {
        expect(Option::Some(14)->exists(fn($it) => $it < 100))->toBeTrue();
    });
    test('returns false for Some and non-matching condition', function () {
        expect(Option::Some(14)->exists(fn($it) => $it > 100))->toBeFalse();
    });
});

describe('->map()', function () {
    test('does nothing for None', function () {
        $tattle = new class { public bool $called = false; };
        $none   = Option::None();
        $mapped = $none->map(function () use ($tattle)
        {
            $tattle->called = true;
            return 'hello';
        });
        expect($mapped)
            ->isNone->toBeTrue()
            ->and($tattle->called)->toBeFalse()
            ->and($mapped)->toBe($none);
    });
    test('maps value for Some', function () {
        expect(Option::Some('abc ')->map(fn($it) => str_repeat($it, 2)))
            ->isSome->toBeTrue()->value->toBe('abc abc ');
    });
    test('throws an exception if mapping returns null', function () {
        expect(fn() => Option::Some('oof')->map(fn($it) => null))->toThrow(InvalidArgumentException::class);
    });
});

describe('->iter()', function () {
    test('does nothing for None', function () {
        $target = new class { public mixed $called = null; };
        Option::None()->iter(function () use ($target) { $target->called = 'uh oh'; });
        expect($target->called)->toBeNull();
    });
    test('iterates for Some', function () {
        $target = new class { public mixed $called = null; };
        Option::Some(33)->iter(function ($it) use ($target) { $target->called = $it; });
        expect($target->called)->toBe(33);
    });
});

describe('->filter()', function () {
    test('does nothing for None', function () {
        $tattle   = new class { public bool $called = false; };
        $none     = Option::None();
        $filtered = $none->filter(function () use ($tattle)
        {
            $tattle->called = true;
            return true;
        });
        expect($filtered)
            ->isNone->toBeTrue()
            ->and($tattle->called)->toBeFalse()
            ->and($filtered)->toBe($none);
    });
    test('returns Some when filter is matched', function () {
        $some     = Option::Some(12);
        $filtered = $some->filter(fn($it) => $it % 2 === 0);
        expect($filtered)
            ->isSome->toBeTrue()
            ->value->toBe(12)
            ->and($filtered)->toBe($some);
    });
    test('returns None when filter is not matched', function () {
        expect(Option::Some(23)->filter(fn($it) => $it % 2 === 0)->isNone)->toBeTrue();
    });
});

describe('->unwrap()', function () {
    test('returns null for None', function () {
        expect(Option::None()->unwrap())->toBeNull();
    });
    test('returns option value for Some', function () {
        expect(Option::Some('boy howdy')->unwrap())->toBe('boy howdy');
    });
});

describe('->tap()', function () {
    test('is called for None', function () {
        $value    = '';
        $original = Option::None();
        $tapped   = $original->tap(
            function (Option $it) use (&$value) { $value = $it->isSome ? $it->value : 'none'; });
        expect($value)->toBe('none')->and($original)->toBe($tapped);
    });
    test('is called for Some', function () {
        $value    = '';
        $original = Option::Some('testing');
        $tapped   = $original->tap(
            function (Option $it) use (&$value) { $value = $it->isSome ? $it->value : 'none'; });
        expect($value)->toBe('testing')->and($original)->toBe($tapped);
    });
});

describe('->toArray()', function () {
    test('returns empty array for None', function () {
        expect(Option::None()->toArray())->not->toBeNull()->toBeEmpty();
    });
    test('returns one-item array for Some', function () {
        expect(Option::Some('15')->toArray())->not->toBeNull()->toBe(['15']);
    });
});

describe('->toPhpOption()', function () {
    test('converts None', function () {
        expect(Option::None()->toPhpOption())
            ->toBeInstanceOf('PhpOption\None')
            ->not->toBeNull()
            ->isDefined()->toBeFalse();
    });
    test('converts Some', function () {
        expect(Option::Some('php')->toPhpOption())
            ->toBeInstanceOf('PhpOption\Some')
            ->not->toBeNull()
            ->isDefined()->toBeTrue()
            ->get()->toBe('php');
    });
});

describe('::Some()', function () {
    test('creates a Some option when given a value', function () {
        expect(Option::Some('hello'))->not->toBeNull()->isSome->toBeTrue();
    });
    test('throws an exception when given null', function () {
        expect(fn() => Option::Some(null))->toThrow(InvalidArgumentException::class);
    });
});

describe('::None()', function () {
    test('creates a None option', function () {
        expect(Option::None())->not->toBeNull()->isNone->toBeTrue();
    });
});

describe('::of()', function () {
    test('creates a None option when given null', function () {
        expect(Option::of(null))->not->toBeNull()->isNone->toBeTrue();
    });
    test('creates a Some option when given a value', function () {
        expect(Option::of('test'))->not->toBeNull()
            ->isSome->toBeTrue()
            ->value->toBe('test');
    });
    test('creates a None option when given PhpOption\None', function () {
        expect(Option::of(None::create()))->isNone->toBeTrue();
    });
    test('creates a Some option when given PhpOption\Some', function () {
        expect(Option::of(Some::create('something')))->isSome->toBeTrue()->value->toBe('something');
    });
});