A player can join a memory game #15

code/src/Memory/Domain/Model/Game/Event/PlayerJoined.php

@@ -0,0 +1,75 @@
+<?php
+declare(strict_types=1);
+
+namespace Gambling\Memory\Domain\Model\Game\Event;
+
+use Gambling\Common\Clock\Clock;
+use Gambling\Common\Domain\DomainEvent;
+use Gambling\Memory\Domain\Model\Game\GameId;
+use Gambling\Memory\Domain\Model\Game\Player;
+
+final class PlayerJoined implements DomainEvent
+{
+    /**
+     * @var GameId
+     */
+    private $gameId;
+
+    /**
+     * @var Player
+     */
+    private $player;
+
+    /**
+     * @var \DateTimeImmutable
+     */
+    private $occurredOn;
+
+    /**
+     * PlayerJoined constructor.
+     *
+     * @param GameId $gameId
+     * @param Player $player
+     */
+    public function __construct(GameId $gameId, Player $player)
+    {
+        $this->gameId = $gameId;
+        $this->player = $player;
+        $this->occurredOn = Clock::instance()->now();
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function aggregateId(): string
+    {
+        return $this->gameId->toString();
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function payload(): array
+    {
+        return [
+            'gameId'   => $this->gameId->toString(),
+            'playerId' => $this->player->id()
+        ];
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function occurredOn(): \DateTimeImmutable
+    {
+        return $this->occurredOn;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function name(): string
+    {
+        return 'PlayerJoined';
+    }
+}

code/src/Memory/Domain/Model/Game/Game.php

@@ -8,6 +8,8 @@
 use Gambling\Common\Domain\IsAggregateRoot;
 use Gambling\Memory\Domain\Model\Game\Dealer\Dealer;
 use Gambling\Memory\Domain\Model\Game\Event\GameOpened;
+use Gambling\Memory\Domain\Model\Game\Event\PlayerJoined;
+use Gambling\Memory\Domain\Model\Game\Exception\PlayerAlreadyJoinedException;
 
 /**
  * Unlike in the connect four context, this game does not use the state pattern.
@@ -85,4 +87,25 @@ public static function open(Dealer $dealer, string $playerId): Game
             ]
         );
     }
+
+    /**
+     * A player joins in the game.
+     *
+     * @param string $playerId
+     *
+     * @throws PlayerAlreadyJoinedException
+     */
+    public function join(string $playerId): void
+    {
+        $player = new Player($playerId);
+        $playerJoined = new PlayerJoined(
+            $this->gameId,
+            $player
+        );
+
+        $this->playerPool = $this->playerPool->join(
+            new Player($playerId)
+        );
+        $this->domainEvents[] = $playerJoined;
+    }
 }

code/tests/unit/Memory/Domain/Model/Game/Event/PlayerJoinedTest.php

@@ -0,0 +1,39 @@
+<?php
+declare(strict_types=1);
+
+namespace Gambling\Memory\Domain\Model\Game\Event;
+
+use Gambling\Common\Clock\Clock;
+use Gambling\Memory\Domain\Model\Game\GameId;
+use Gambling\Memory\Domain\Model\Game\Player;
+use PHPUnit\Framework\TestCase;
+
+final class PlayerJoinedTest extends TestCase
+{
+    /**
+     * @test
+     */
+    public function itShouldBeCreatedWithItsValues(): void
+    {
+        Clock::instance()->freeze();
+
+        $gameId = GameId::generate();
+        $playerId = 'playerId';
+        $payload = [
+            'gameId'        => $gameId->toString(),
+            'playerId'      => $playerId
+        ];
+
+        $playerJoined = new PlayerJoined(
+            $gameId,
+            new Player($playerId)
+        );
+
+        $this->assertSame('PlayerJoined', $playerJoined->name());
+        $this->assertSame($gameId->toString(), $playerJoined->aggregateId());
+        $this->assertSame(Clock::instance()->now(), $playerJoined->occurredOn());
+        $this->assertSame($payload, $playerJoined->payload());
+
+        Clock::instance()->resume();
+    }
+}

code/tests/unit/Memory/Domain/Model/Game/GameTest.php

@@ -5,6 +5,7 @@
 
 use Gambling\Memory\Domain\Model\Game\Dealer\LazyDealer;
 use Gambling\Memory\Domain\Model\Game\Event\GameOpened;
+use Gambling\Memory\Domain\Model\Game\Event\PlayerJoined;
 use PHPUnit\Framework\TestCase;
 
 class GameTest extends TestCase
@@ -28,4 +29,39 @@ public function aGameCanBeOpened(): void
         $this->assertSame(10, $gameOpened->payload()['numberOfCards']);
         $this->assertSame('playerId1', $gameOpened->payload()['playerId']);
     }
+
+    /**
+     * @test
+     */
+    public function aPlayerCanJoin(): void
+    {
+        $game = $this->createOpenGame();
+
+        $game->join('playerId2');
+
+        $domainEvents = $game->flushDomainEvents();
+        $playerJoined = $domainEvents[0];
+
+        $this->assertCount(1, $domainEvents);
+        $this->assertInstanceOf(PlayerJoined::class, $playerJoined);
+        $this->assertSame($game->id()->toString(), $playerJoined->aggregateId());
+        $this->assertSame('playerId2', $playerJoined->payload()['playerId']);
+    }
+
+    /**
+     * Returns an open game ready for testing.
+     *
+     * @return Game
+     */
+    private function createOpenGame(): Game
+    {
+        $game = Game::open(
+            new LazyDealer(5),
+            'playerId1'
+        );
+
+        $game->flushDomainEvents();
+
+        return $game;
+    }
 }