inspired-by-fsharp/tests/OptionTest.php

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

declare(strict_types=1);

namespace Test;

use BadMethodCallException;
use BitBadger\InspiredByFSharp\Option;
use InvalidArgumentException;
use PhpOption\{None, Some};
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);
        $this->assertTrue($it->isSome(), '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();
    }

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

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

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

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

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

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

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

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

    #[TestDox('GetOrThrow succeeds with Some')]
    public function testGetOrThrowSucceedsWithSome(): void
    {
        $value = Option::Some('no throw')->getOrThrow(fn() => new BadMethodCallException('oops'));
        $this->assertEquals('no throw', $value, 'The "Some" value should have been returned');
    }

    #[TestDox('GetOrThrow succeeds with None')]
    public function testGetOrThrowSucceedsWithNone(): void
    {
        $this->expectException(BadMethodCallException::class);
        Option::None()->getOrThrow(fn() => new BadMethodCallException('oops'));
    }

    #[TestDox('Bind succeeds with None')]
    public function testBindSucceedsWithNone(): void
    {
        $original = Option::None();
        $bound    = $original->bind(fn($it) => Option::Some('value'));
        $this->assertTrue($bound->isNone(), 'The option should have been None');
        $this->assertSame($original, $bound, 'The same None instance should have been returned');
    }

    #[TestDox('Bind succeeds with Some and Some')]
    public function testBindSucceedsWithSomeAndSome(): void
    {
        $bound = Option::Some('hello')->bind(fn($it) => Option::Some('goodbye'));
        $this->assertTrue($bound->isSome(), 'The option should have been Some');
        $this->assertEquals('goodbye', $bound->get(), 'The bound function was not called');
    }

    #[TestDox('Bind succeeds with Some and None')]
    public function testBindSucceedsWithSomeAndNone(): void
    {
        $bound = Option::Some('greetings')->bind(fn($it) => Option::None());
        $this->assertTrue($bound->isNone(), 'The option should have been None');
    }

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

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

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

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

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

    #[TestDox('Exists succeeds with Some when matching')]
    public function testExistsSucceedsWithSomeWhenMatching(): void
    {
        $this->assertTrue(Option::Some(14)->exists(fn($it) => $it < 100), 'Exists should have returned true');
    }

    #[TestDox('Exists succeeds with Some when not matching')]
    public function testExistsSucceedsWithSomeWhenNotMatching(): void
    {
        $this->assertFalse(Option::Some(14)->exists(fn($it) => $it > 100), 'Exists should have returned false');
    }

    #[TestDox('Exists succeeds with None')]
    public function testExistsSucceedsWithNone(): void
    {
        $this->assertFalse(Option::None()->exists(fn($it) => true), 'Exists should have returned false');
    }

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

    #[TestDox('Map succeeds with Some')]
    public function testMapSucceedsWithSome(): void
    {
        $mapped = Option::Some('abc ')->map(fn($it) => str_repeat($it, 2));
        $this->assertTrue($mapped->isSome(), '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
    {
        $this->expectException(InvalidArgumentException::class);
        Option::Some('oof')->map(fn($it) => null);
    }

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

    #[TestDox('Iter succeeds with Some')]
    public function testIterSucceedsWithSome(): void
    {
        $target = new class { public mixed $called = null; };
        Option::Some(33)->iter(function ($it) use ($target) { $target->called = $it; });
        $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 = $none->filter(function () use ($tattle)
        {
            $tattle->called = true;
            return true;
        });
        $this->assertTrue($filtered->isNone(), 'The filtered option should have been "None"');
        $this->assertFalse($tattle->called, 'The callable should not have been called');
        $this->assertSame($none, $filtered, 'The "None" instance returned should have been the one passed');
    }

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

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

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

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

    #[TestDox('Tap succeeds with Some')]
    public function testTapSucceedsWithSome(): void
    {
        $value    = '';
        $original = Option::Some('testing');
        $tapped   = $original->tap(
            function (Option $it) use (&$value) { $value = $it->isSome() ? $it->get() : 'none'; });
        $this->assertEquals('testing', $value, 'The tapped function was not called');
        $this->assertSame($original, $tapped, 'The same option should have been returned');
    }

    #[TestDox('Tap succeeds with None')]
    public function testTapSucceedsWithNone(): void
    {
        $value    = '';
        $original = Option::None();
        $tapped   = $original->tap(
            function (Option $it) use (&$value) { $value = $it->isSome() ? $it->get() : 'none'; });
        $this->assertEquals('none', $value, 'The tapped function was not called');
        $this->assertSame($original, $tapped, 'The same option should have been returned');
    }

    #[TestDox('ToArray succeeds with Some')]
    public function testToArraySucceedsWithSome(): void
    {
        $arr = Option::Some('15')->toArray();
        $this->assertNotNull($arr, 'The array should not have been null');
        $this->assertEquals(['15'], $arr, 'The array was not created correctly');
    }

    #[TestDox('ToArray succeeds with None')]
    public function testToArraySucceedsWithNone(): void
    {
        $arr = Option::None()->toArray();
        $this->assertNotNull($arr, 'The array should not have been null');
        $this->assertEmpty($arr, 'The array should have been empty');
    }

    #[TestDox('ToPhpOption succeeds for Some')]
    public function testToPhpOptionSucceedsForSome(): void
    {
        $opt = Option::Some('php')->toPhpOption();
        $this->assertNotNull($opt, 'The PhpOption should not have been null');
        $this->assertInstanceOf('PhpOption\Some', $opt, 'The PhpOption should have been "Some"');
        $this->assertTrue($opt->isDefined(), 'There should have been a value for the PhpOption');
        $this->assertEquals('php', $opt->get(), 'The value was not correct');
    }

    #[TestDox('ToPhpOption succeeds for None')]
    public function testToPhpOptionSucceedsForNone(): void
    {
        $opt = Option::None()->toPhpOption();
        $this->assertNotNull($opt, 'The PhpOption should not have been null');
        $this->assertInstanceOf('PhpOption\None', $opt, 'The PhpOption should have been "None"');
        $this->assertFalse($opt->isDefined(), 'There should not have been a value for the PhpOption');
    }

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

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

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

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

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

    #[TestDox('Of succeeds with PhpOption\Some')]
    public function testOfSucceedsWithPhpOptionSome(): void
    {
        $it = Option::of(Some::create('something'));
        $this->assertTrue($it->isSome(), 'A "Some" PhpOption should have created a "Some" option');
        $this->assertEquals('something', $it->get(), 'The value was not assigned correctly');
    }

    #[TestDox('Of succeeds with PhpOption\None')]
    public function testOfSucceedsWithPhpOptionNone(): void
    {
        $it = Option::of(None::create());
        $this->assertTrue($it->isNone(), 'A "None" PhpOption should have created a "None" option');
    }
}