[10.x] Introduce Observe attribute for models (#49843)

* Introduce Observe attribute for models

* fix tests

* fix styling

* rename file

---------

Co-authored-by: Taylor Otwell <taylor@laravel.com>

src/Illuminate/Database/Eloquent/Attributes/ObservedBy.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace Illuminate\Database\Eloquent\Attributes;
+
+use Attribute;
+
+#[Attribute(Attribute::TARGET_CLASS | Attribute::IS_REPEATABLE)]
+class ObservedBy
+{
+    /**
+     * Create a new attribute instance.
+     *
+     * @param  array|string  $classes
+     * @return void
+     */
+    public function __construct(array|string $classes)
+    {
+    }
+}

src/Illuminate/Database/Eloquent/Concerns/HasEvents.php

@@ -3,9 +3,11 @@
 namespace Illuminate\Database\Eloquent\Concerns;
 
 use Illuminate\Contracts\Events\Dispatcher;
+use Illuminate\Database\Eloquent\Attributes\ObservedBy;
 use Illuminate\Events\NullDispatcher;
 use Illuminate\Support\Arr;
 use InvalidArgumentException;
+use ReflectionClass;
 
 trait HasEvents
 {
@@ -27,6 +29,31 @@ trait HasEvents
      */
     protected $observables = [];
 
+    /**
+     * Boot the has event trait for a model.
+     *
+     * @return void
+     */
+    public static function bootHasEvents()
+    {
+        static::observe(static::resolveObserveAttributes());
+    }
+
+    /**
+     * Resolve the observe class names from the attributes.
+     *
+     * @return array
+     */
+    public static function resolveObserveAttributes()
+    {
+        $reflectionClass = new ReflectionClass(static::class);
+
+        return collect($reflectionClass->getAttributes(ObservedBy::class))
+            ->map(fn ($attribute) => $attribute->getArguments())
+            ->flatten()
+            ->all();
+    }
+
     /**
      * Register observers with the model.
      *

tests/Auth/AuthListenersSendEmailVerificationNotificationHandleFunctionTest.php

@@ -6,6 +6,7 @@
 use Illuminate\Auth\Listeners\SendEmailVerificationNotification;
 use Illuminate\Contracts\Auth\MustVerifyEmail;
 use Illuminate\Foundation\Auth\User;
+use Mockery as m;
 use PHPUnit\Framework\TestCase;
 
 class AuthListenersSendEmailVerificationNotificationHandleFunctionTest extends TestCase
@@ -29,8 +30,8 @@ public function testWillExecuted()
      */
     public function testUserIsNotInstanceOfMustVerifyEmail()
     {
-        $user = $this->getMockBuilder(User::class)->getMock();
-        $user->expects($this->never())->method('sendEmailVerificationNotification');
+        $user = m::mock(User::class);
+        $user->shouldNotReceive('sendEmailVerificationNotification');
 
         $listener = new SendEmailVerificationNotification;
 

tests/Database/DatabaseEloquentModelTest.php

@@ -15,6 +15,7 @@
 use Illuminate\Database\Connection;
 use Illuminate\Database\ConnectionResolverInterface;
 use Illuminate\Database\ConnectionResolverInterface as Resolver;
+use Illuminate\Database\Eloquent\Attributes\ObservedBy;
 use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Casts\ArrayObject;
 use Illuminate\Database\Eloquent\Casts\AsArrayObject;
@@ -1893,6 +1894,26 @@ public function testModelObserversCanBeAttachedToModelsThroughAnArray()
         EloquentModelStub::flushEventListeners();
     }
 
+    public function testModelObserversCanBeAttachedToModelsWithStringUsingAttribute()
+    {
+        EloquentModelWithObserveAttributeStub::setEventDispatcher($events = m::mock(Dispatcher::class));
+        $events->shouldReceive('dispatch');
+        $events->shouldReceive('listen')->once()->with('eloquent.creating: Illuminate\Tests\Database\EloquentModelWithObserveAttributeStub', EloquentTestObserverStub::class.'@creating');
+        $events->shouldReceive('listen')->once()->with('eloquent.saved: Illuminate\Tests\Database\EloquentModelWithObserveAttributeStub', EloquentTestObserverStub::class.'@saved');
+        $events->shouldReceive('forget');
+        EloquentModelWithObserveAttributeStub::flushEventListeners();
+    }
+
+    public function testModelObserversCanBeAttachedToModelsThroughAnArrayUsingAttribute()
+    {
+        EloquentModelWithObserveAttributeUsingArrayStub::setEventDispatcher($events = m::mock(Dispatcher::class));
+        $events->shouldReceive('dispatch');
+        $events->shouldReceive('listen')->once()->with('eloquent.creating: Illuminate\Tests\Database\EloquentModelWithObserveAttributeUsingArrayStub', EloquentTestObserverStub::class.'@creating');
+        $events->shouldReceive('listen')->once()->with('eloquent.saved: Illuminate\Tests\Database\EloquentModelWithObserveAttributeUsingArrayStub', EloquentTestObserverStub::class.'@saved');
+        $events->shouldReceive('forget');
+        EloquentModelWithObserveAttributeUsingArrayStub::flushEventListeners();
+    }
+
     public function testThrowExceptionOnAttachingNotExistsModelObserverWithString()
     {
         $this->expectException(InvalidArgumentException::class);
@@ -3334,6 +3355,18 @@ public function uniqueIds()
     }
 }
 
+#[ObservedBy(EloquentTestObserverStub::class)]
+class EloquentModelWithObserveAttributeStub extends EloquentModelStub
+{
+    //
+}
+
+#[ObservedBy([EloquentTestObserverStub::class])]
+class EloquentModelWithObserveAttributeUsingArrayStub extends EloquentModelStub
+{
+    //
+}
+
 class EloquentModelSavingEventStub
 {
     //