BattleForge/tests/Unit/Domain/UnitStateTest.php

<?php

declare(strict_types=1);

namespace BattleForge\Tests\Unit\Domain;

use BattleForge\Domain\Position;
use BattleForge\Domain\UnitState;
use InvalidArgumentException;
use PHPUnit\Framework\Attributes\DataProvider;
use PHPUnit\Framework\TestCase;

final class UnitStateTest extends TestCase
{
    /**
     * @param callable(): UnitState $createUnit
     */
    #[DataProvider('invalidUnitProvider')]
    public function testItRejectsInvalidConstructorArguments(callable $createUnit): void
    {
        $this->expectException(InvalidArgumentException::class);

        $createUnit();
    }

    /**
     * @return iterable<string, array{callable(): UnitState}>
     */
    public static function invalidUnitProvider(): iterable
    {
        yield 'empty unit id' => [
            static fn (): UnitState => new UnitState('', 'alpha', new Position(0, 0), 10, 10, 4, 2, 4, 2),
        ];
        yield 'empty team id' => [
            static fn (): UnitState => new UnitState('unit-1', '', new Position(0, 0), 10, 10, 4, 2, 4, 2),
        ];
        yield 'zero maximum health' => [
            static fn (): UnitState => new UnitState('unit-1', 'alpha', new Position(0, 0), 0, 0, 4, 2, 4, 2),
        ];
        yield 'negative health' => [
            static fn (): UnitState => new UnitState('unit-1', 'alpha', new Position(0, 0), 10, -1, 4, 2, 4, 2),
        ];
        yield 'health above maximum' => [
            static fn (): UnitState => new UnitState('unit-1', 'alpha', new Position(0, 0), 10, 11, 4, 2, 4, 2),
        ];
        yield 'negative attack' => [
            static fn (): UnitState => new UnitState('unit-1', 'alpha', new Position(0, 0), 10, 10, -1, 2, 4, 2),
        ];
        yield 'negative defense' => [
            static fn (): UnitState => new UnitState('unit-1', 'alpha', new Position(0, 0), 10, 10, 4, -1, 4, 2),
        ];
        yield 'zero speed' => [
            static fn (): UnitState => new UnitState('unit-1', 'alpha', new Position(0, 0), 10, 10, 4, 2, 0, 2),
        ];
        yield 'negative actions remaining' => [
            static fn (): UnitState => new UnitState('unit-1', 'alpha', new Position(0, 0), 10, 10, 4, 2, 4, -1),
        ];
        yield 'too many actions remaining' => [
            static fn (): UnitState => new UnitState('unit-1', 'alpha', new Position(0, 0), 10, 10, 4, 2, 4, 3),
        ];
    }

    public function testItReportsWhetherItIsDefeated(): void
    {
        self::assertTrue($this->unit(health: 0)->isDefeated());
        self::assertFalse($this->unit(health: 1)->isDefeated());
    }

    public function testMovingReturnsAChangedCopy(): void
    {
        $unit = $this->unit();
        $moved = $unit->moveTo(new Position(2, 3));

        self::assertNotSame($unit, $moved);
        self::assertSame('0:0', $unit->position->key());
        self::assertSame('2:3', $moved->position->key());
    }

    public function testSpendingAnActionReturnsAChangedCopyAndRejectsExhaustedUnits(): void
    {
        $unit = $this->unit(actionsRemaining: 1);
        $spent = $unit->spendAction();

        self::assertSame(1, $unit->actionsRemaining);
        self::assertSame(0, $spent->actionsRemaining);

        $this->expectException(InvalidArgumentException::class);
        $spent->spendAction();
    }

    public function testDamageCannotReduceHealthBelowZero(): void
    {
        $unit = $this->unit(health: 3);
        $damaged = $unit->takeDamage(5);

        self::assertSame(3, $unit->health);
        self::assertSame(0, $damaged->health);
    }

    public function testNegativeDamageIsANoOp(): void
    {
        $unit = $this->unit(health: 7);
        $damaged = $unit->takeDamage(-3);

        self::assertNotSame($unit, $damaged);
        self::assertSame(7, $damaged->health);
    }

    public function testMarkingAttackedReturnsAChangedCopy(): void
    {
        $unit = $this->unit();
        $attacked = $unit->markAttacked();

        self::assertFalse($unit->hasAttacked);
        self::assertTrue($attacked->hasAttacked);
    }

    public function testStartingTurnResetsALivingUnit(): void
    {
        $unit = $this->unit(actionsRemaining: 0, hasAttacked: true);
        $started = $unit->startTurn();

        self::assertNotSame($unit, $started);
        self::assertSame(2, $started->actionsRemaining);
        self::assertFalse($started->hasAttacked);
    }

    public function testStartingTurnReturnsTheSameDefeatedUnit(): void
    {
        $unit = $this->unit(health: 0, actionsRemaining: 0, hasAttacked: true);

        self::assertSame($unit, $unit->startTurn());
    }

    private function unit(
        int $health = 10,
        int $actionsRemaining = 2,
        bool $hasAttacked = false,
    ): UnitState {
        return new UnitState(
            'unit-1',
            'alpha',
            new Position(0, 0),
            10,
            $health,
            4,
            2,
            4,
            $actionsRemaining,
            $hasAttacked,
        );
    }
}