inspired-by-fsharp/tests/OptionTest.php

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

declare(strict_types=1);

namespace Test;

use BitBadger\InspiredByFSharp\Option;
use InvalidArgumentException;
use PHPUnit\Framework\Attributes\TestDox;
use PHPUnit\Framework\TestCase;

/**
 * Unit tests for the Option class
 */
class OptionTest extends TestCase
{
    #[TestDox('Get succeeds for Some')]
    public function testGetSucceedsForSome(): void
    {
        $it = Option::Some(9);
        $this->assertTrue(Option::isSome($it), 'The option should have been "Some"');
        $this->assertEquals(9, $it->get(), 'The value was incorrect');
    }

    #[TestDox('Get fails for None')]
    public function testGetFailsForNone(): void
    {
        $this->expectException(InvalidArgumentException::class);
        Option::None()->get();
    }

    public function testSomeSucceedsWithValue(): void
    {
        $it = Option::Some('hello');
        $this->assertTrue(Option::isSome($it), 'The option should have been "Some"');
    }

    public function testSomeFailsWithNull(): void
    {
        $this->expectException(InvalidArgumentException::class);
        Option::Some(null);
    }

    public function testNoneSucceeds(): void
    {
        $it = Option::None();
        $this->assertTrue(Option::isNone($it), 'The option should have been "None"');
    }

    public function testOfSucceedsWithNull(): void
    {
        $it = Option::of(null);
        $this->assertTrue(Option::isNone($it), '"null" should have created a "None" option');
    }

    public function testOfSucceedsWithNonNull(): void
    {
        $it = Option::of('test');
        $this->assertTrue(Option::isSome($it), 'A non-null value should have created a "Some" option');
        $this->assertEquals('test', $it->get(), 'The value was not assigned correctly');
    }

    #[TestDox('IsNone succeeds with None')]
    public function testIsNoneSucceedsWithNone(): void
    {
        $this->assertTrue(Option::isNone(Option::None()), '"None" should return true');
    }

    #[TestDox('IsNone succeeds with Some')]
    public function testIsNoneSucceedsWithSome(): void
    {
        $this->assertFalse(Option::isNone(Option::Some(8)), '"Some" should return false');
    }

    #[TestDox('IsSome succeeds with None')]
    public function testIsSomeSucceedsWithNone(): void
    {
        $this->assertFalse(Option::isSome(Option::None()), '"None" should return false');
    }

    #[TestDox('IsSome succeeds with Some')]
    public function testIsSomeSucceedsWithSome(): void
    {
        $this->assertTrue(Option::isSome(Option::Some('boo')), '"Some" should return true');
    }

    #[TestDox('DefaultValue succeeds with None')]
    public function testDefaultValueSucceedsWithNone(): void
    {
        $this->assertEquals('yes', Option::defaultValue('yes', Option::None()), 'Value should have been default');
    }

    #[TestDox('DefaultValue succeeds with Some')]
    public function testDefaultValueSucceedsWithSome(): void
    {
        $this->assertEquals('no', Option::defaultValue('yes', Option::Some('no')),
            'Value should have been from option');
    }

    #[TestDox('GetOrCall succeeds with None')]
    public function testGetOrCallSucceedsWithNone(): void
    {
        $value = Option::getOrCall(new class { public function __invoke(): string { return 'called'; } },
            Option::None());
        $this->assertEquals('called', $value, 'The value should have been obtained from the callable');
    }

    #[TestDox('GetOrCall succeeds with Some')]
    public function testGetOrCallSucceedsWithSome(): void
    {
        $value = Option::getOrCall(new class { public function __invoke(): string { return 'called'; } },
            Option::Some('passed'));
        $this->assertEquals('passed', $value, 'The value should have been obtained from the option');
    }

    #[TestDox('Map succeeds with None')]
    public function testMapSucceedsWithNone(): void
    {
        $tattle = new class { public bool $called = false; };
        $none   = Option::None();
        $mapped = Option::map(function ($ignored) use ($tattle)
        {
            $tattle->called = true;
            return 'hello';
        }, $none);
        $this->assertTrue(Option::isNone($mapped), 'The mapped option should be "None"');
        $this->assertFalse($tattle->called, 'The mapping function should not have been called');
        $this->assertNotSame($none, $mapped, 'There should have been a new "None" instance returned');
    }

    #[TestDox('Map succeeds with Some')]
    public function testMapSucceedsWithSome(): void
    {
        $mapped = Option::map(fn($it) => str_repeat($it, 2), Option::Some('abc '));
        $this->assertTrue(Option::isSome($mapped), 'The mapped option should be "Some"');
        $this->assertEquals('abc abc ', $mapped->get(), 'The mapping function was not called correctly');
    }

    #[TestDox('Map fails with Some when mapping is null')]
    public function testMapFailsWithSomeWhenMappingIsNull(): void
    {
        $this->expectException(InvalidArgumentException::class);
        Option::map(fn($it) => null, Option::Some('oof'));
    }

    #[TestDox('Iter succeeds with None')]
    public function testIterSucceedsWithNone(): void
    {
        $target = new class { public mixed $called = null; };
        Option::iter(function ($ignored) use ($target) { $target->called = 'uh oh'; }, Option::None());
        $this->assertNull($target->called, 'The function should not have been called');
    }

    #[TestDox('Iter succeeds with Some')]
    public function testIterSucceedsWithSome(): void
    {
        $target = new class { public mixed $called = null; };
        Option::iter(function ($it) use ($target) { $target->called = $it; }, Option::Some(33));
        $this->assertEquals(33, $target->called, 'The function should have been called with the "Some" value');
    }

    #[TestDox('Filter succeeds with None')]
    public function testFilterSucceedsWithNone(): void
    {
        $tattle   = new class { public bool $called = false; };
        $none     = Option::None();
        $filtered = Option::filter(function ($ignored) use ($tattle)
        {
            $tattle->called = true;
            return true;
        }, $none);
        $this->assertTrue(Option::isNone($filtered), 'The filtered option should have been "None"');
        $this->assertFalse($tattle->called, 'The callable should not have been called');
    }

    #[TestDox('Filter succeeds with Some when true')]
    public function testFilterSucceedsWithSomeWhenTrue(): void
    {
        $some     = Option::Some(12);
        $filtered = Option::filter(fn($it) => $it % 2 === 0, $some);
        $this->assertTrue(Option::isSome($filtered), 'The filtered option should have been "Some"');
        $this->assertEquals(12, $filtered->get(), 'The filtered option value is incorrect');
        $this->assertNotSame($some, $filtered, 'There should have been a new option instance returned');
    }

    #[TestDox('Filter succeeds with Some when false')]
    public function testFilterSucceedsWithSomeWhenFalse(): void
    {
        $some     = Option::Some(23);
        $filtered = Option::filter(fn($it) => $it % 2 === 0, $some);
        $this->assertTrue(Option::isNone($filtered), 'The filtered option should have been "None"');
    }

    #[TestDox('Is succeeds with None')]
    public function testIsSucceedsWithNone(): void
    {
        $this->assertFalse(Option::is(null, Option::None()), '"None" should always return false');
    }

    #[TestDox('Is succeeds with Some when strictly equal')]
    public function testIsSucceedsWithSomeWhenStrictlyEqual(): void
    {
        $this->assertTrue(Option::is(3, Option::Some(3)), '"Some" with strict equality should be true');
    }

    #[TestDox('Is succeeds with Some when strictly unequal')]
    public function testIsSucceedsWithSomeWhenStrictlyUnequal(): void
    {
        $this->assertFalse(Option::is(3, Option::Some('3')), '"Some" with strict equality should be false');
    }

    #[TestDox('Is succeeds with Some when loosely equal')]
    public function testIsSucceedsWithSomeWhenLooselyEqual(): void
    {
        $this->assertTrue(Option::is(3, Option::Some('3'), strict: false), '"Some" with loose equality should be true');
    }

    #[TestDox('Is succeeds with Some when loosely unequal')]
    public function testIsSucceedsWithSomeWhenLooselyUnequal(): void
    {
        $this->assertFalse(Option::is(4, Option::Some('3'), strict: false),
            '"Some" with loose equality should be false');
    }

    #[TestDox('Unwrap succeeds with None')]
    public function testUnwrapSucceedsWithNone(): void
    {
        $this->assertNull(Option::unwrap(Option::None()), '"None" should return null');
    }

    #[TestDox('Unwrap succeeds with Some')]
    public function testUnwrapSucceedsWithSome(): void
    {
        $this->assertEquals('boy howdy', Option::unwrap(Option::Some('boy howdy')), '"Some" should return its value');
    }
}