add strict apply method & extract the default apply method

src/Aggregate/AggregateRoot.php

@@ -4,11 +4,6 @@
 
 namespace Patchlevel\EventSourcing\Aggregate;
 
-use function end;
-use function explode;
-use function get_class;
-use function method_exists;
-
 abstract class AggregateRoot
 {
     /** @var array<AggregateChanged> */
@@ -23,6 +18,8 @@ final protected function __construct()
 
     abstract public function aggregateRootId(): string;
 
+    abstract protected function apply(AggregateChanged $event): void;
+
     protected function record(AggregateChanged $event): void
     {
         $this->playhead++;
@@ -61,24 +58,6 @@ public static function createFromEventStream(array $stream): self
         return $self;
     }
 
-    protected function apply(AggregateChanged $event): void
-    {
-        $method = $this->findApplyMethod($event);
-
-        if (!method_exists($this, $method)) {
-            return;
-        }
-
-        $this->$method($event);
-    }
-
-    private function findApplyMethod(AggregateChanged $event): string
-    {
-        $classParts = explode('\\', get_class($event));
-
-        return 'apply' . end($classParts);
-    }
-
     public function playhead(): int
     {
         return $this->playhead;

src/Aggregate/ApplyMethodNotFound.php

@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\EventSourcing\Aggregate;
+
+use function get_class;
+use function sprintf;
+
+class ApplyMethodNotFound extends AggregateException
+{
+    public function __construct(AggregateRoot $aggregate, AggregateChanged $event, string $method)
+    {
+        parent::__construct(sprintf(
+            'Apply method "%s::%s" could not be found for the event "%s"',
+            get_class($aggregate),
+            $method,
+            get_class($event)
+        ));
+    }
+}

src/Aggregate/DefaultApplyMethod.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\EventSourcing\Aggregate;
+
+use function end;
+use function explode;
+use function get_class;
+use function method_exists;
+
+/**
+ * @psalm-require-extends AggregateRoot
+ */
+trait DefaultApplyMethod
+{
+    protected function apply(AggregateChanged $event): void
+    {
+        $method = $this->findApplyMethod($event);
+
+        if (!method_exists($this, $method)) {
+            return;
+        }
+
+        $this->$method($event);
+    }
+
+    private function findApplyMethod(AggregateChanged $event): string
+    {
+        $classParts = explode('\\', get_class($event));
+
+        return 'apply' . end($classParts);
+    }
+}

src/Aggregate/StrictApplyMethod.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\EventSourcing\Aggregate;
+
+use function end;
+use function explode;
+use function get_class;
+use function method_exists;
+
+/**
+ * @psalm-require-extends AggregateRoot
+ */
+trait StrictApplyMethod
+{
+    protected function apply(AggregateChanged $event): void
+    {
+        $method = $this->findApplyMethod($event);
+
+        if (!method_exists($this, $method)) {
+            throw new ApplyMethodNotFound($this, $event, $method);
+        }
+
+        $this->$method($event);
+    }
+
+    private function findApplyMethod(AggregateChanged $event): string
+    {
+        $classParts = explode('\\', get_class($event));
+
+        return 'apply' . end($classParts);
+    }
+}

tests/Integration/BasicImplementation/Aggregate/Profile.php

@@ -4,11 +4,14 @@
 
 namespace Patchlevel\EventSourcing\Tests\Integration\BasicImplementation\Aggregate;
 
+use Patchlevel\EventSourcing\Aggregate\DefaultApplyMethod;
 use Patchlevel\EventSourcing\Aggregate\SnapshotableAggregateRoot;
 use Patchlevel\EventSourcing\Tests\Integration\BasicImplementation\Events\ProfileCreated;
 
 final class Profile extends SnapshotableAggregateRoot
 {
+    use DefaultApplyMethod;
+
     private string $id;
 
     public function aggregateRootId(): string

tests/Integration/Pipeline/Aggregate/Profile.php

@@ -5,13 +5,16 @@
 namespace Patchlevel\EventSourcing\Tests\Integration\Pipeline\Aggregate;
 
 use Patchlevel\EventSourcing\Aggregate\AggregateRoot;
+use Patchlevel\EventSourcing\Aggregate\DefaultApplyMethod;
 use Patchlevel\EventSourcing\Tests\Integration\Pipeline\Events\NewVisited;
 use Patchlevel\EventSourcing\Tests\Integration\Pipeline\Events\OldVisited;
 use Patchlevel\EventSourcing\Tests\Integration\Pipeline\Events\PrivacyAdded;
 use Patchlevel\EventSourcing\Tests\Integration\Pipeline\Events\ProfileCreated;
 
 final class Profile extends AggregateRoot
 {
+    use DefaultApplyMethod;
+
     private string $id;
     private bool $privacy;
     private int $visited;

tests/Unit/Aggregate/AggregateRootWithStrictApplyTest.php

@@ -0,0 +1,61 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\EventSourcing\Tests\Unit\Aggregate;
+
+use Patchlevel\EventSourcing\Aggregate\ApplyMethodNotFound;
+use Patchlevel\EventSourcing\Tests\Unit\Fixture\Email;
+use Patchlevel\EventSourcing\Tests\Unit\Fixture\Message;
+use Patchlevel\EventSourcing\Tests\Unit\Fixture\MessageId;
+use Patchlevel\EventSourcing\Tests\Unit\Fixture\ProfileId;
+use Patchlevel\EventSourcing\Tests\Unit\Fixture\ProfileWithStrictApply;
+use PHPUnit\Framework\TestCase;
+
+class AggregateRootWithStrictApplyTest extends TestCase
+{
+    public function testApplyMethod(): void
+    {
+        $id = ProfileId::fromString('1');
+        $email = Email::fromString('david.badura@patchlevel.de');
+
+        $profile = ProfileWithStrictApply::createProfile($id, $email);
+
+        self::assertEquals('1', $profile->aggregateRootId());
+        self::assertEquals(1, $profile->playhead());
+        self::assertEquals($id, $profile->id());
+        self::assertEquals($email, $profile->email());
+
+        $events = $profile->releaseEvents();
+
+        self::assertCount(1, $events);
+        $event = $events[0];
+        self::assertEquals(1, $event->playhead());
+    }
+
+    public function testEventWithoutApplyMethod(): void
+    {
+        $this->expectException(ApplyMethodNotFound::class);
+
+        $profileId = ProfileId::fromString('1');
+        $email = Email::fromString('david.badura@patchlevel.de');
+
+        $messageId = MessageId::fromString('2');
+
+        $profile = ProfileWithStrictApply::createProfile($profileId, $email);
+
+        $events = $profile->releaseEvents();
+
+        self::assertCount(1, $events);
+        self::assertEquals(1, $profile->playhead());
+        $event = $events[0];
+        self::assertEquals(1, $event->playhead());
+
+        $profile->publishMessage(
+            Message::create(
+                $messageId,
+                'foo'
+            )
+        );
+    }
+}

tests/Unit/Fixture/Profile.php

@@ -5,9 +5,12 @@
 namespace Patchlevel\EventSourcing\Tests\Unit\Fixture;
 
 use Patchlevel\EventSourcing\Aggregate\AggregateRoot;
+use Patchlevel\EventSourcing\Aggregate\DefaultApplyMethod;
 
 final class Profile extends AggregateRoot
 {
+    use DefaultApplyMethod;
+
     private ProfileId $id;
     private Email $email;
     /** @var array<Message> */

tests/Unit/Fixture/ProfileWithSnapshot.php

@@ -4,10 +4,13 @@
 
 namespace Patchlevel\EventSourcing\Tests\Unit\Fixture;
 
+use Patchlevel\EventSourcing\Aggregate\DefaultApplyMethod;
 use Patchlevel\EventSourcing\Aggregate\SnapshotableAggregateRoot;
 
 final class ProfileWithSnapshot extends SnapshotableAggregateRoot
 {
+    use DefaultApplyMethod;
+
     private ProfileId $id;
     private Email $email;
     /** @var array<Message> */

tests/Unit/Fixture/ProfileWithStrictApply.php

@@ -0,0 +1,58 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\EventSourcing\Tests\Unit\Fixture;
+
+use Patchlevel\EventSourcing\Aggregate\AggregateRoot;
+use Patchlevel\EventSourcing\Aggregate\StrictApplyMethod;
+
+final class ProfileWithStrictApply extends AggregateRoot
+{
+    use StrictApplyMethod;
+
+    private ProfileId $id;
+    private Email $email;
+
+    public function id(): ProfileId
+    {
+        return $this->id;
+    }
+
+    public function email(): Email
+    {
+        return $this->email;
+    }
+
+    public static function createProfile(ProfileId $id, Email $email): self
+    {
+        $self = new self();
+        $self->record(ProfileCreated::raise($id, $email));
+
+        return $self;
+    }
+
+    public function publishMessage(Message $message): void
+    {
+        $this->record(MessagePublished::raise(
+            $this->id,
+            $message,
+        ));
+    }
+
+    public function visitProfile(ProfileId $profileId): void
+    {
+        $this->record(ProfileVisited::raise($this->id, $profileId));
+    }
+
+    protected function applyProfileCreated(ProfileCreated $event): void
+    {
+        $this->id = $event->profileId();
+        $this->email = $event->email();
+    }
+
+    public function aggregateRootId(): string
+    {
+        return $this->id->toString();
+    }
+}