Added missing code to set locale from model preferred locale (#45308)

Author: clementbirkle

src/Illuminate/Mail/Mailable.php

@@ -10,6 +10,7 @@
 use Illuminate\Contracts\Queue\Factory as Queue;
 use Illuminate\Contracts\Support\Htmlable;
 use Illuminate\Contracts\Support\Renderable;
+use Illuminate\Contracts\Translation\HasLocalePreference;
 use Illuminate\Support\Collection;
 use Illuminate\Support\HtmlString;
 use Illuminate\Support\Str;
@@ -577,6 +578,10 @@ public function hasFrom($address, $name = null)
      */
     public function to($address, $name = null)
     {
+        if (! $this->locale && $address instanceof HasLocalePreference) {
+            $this->locale($address->preferredLocale());
+        }
+
         return $this->setAddress($address, $name, 'to');
     }
 

tests/Integration/Mail/SendingMailWithLocaleTest.php

@@ -95,6 +95,11 @@ public function testLocaleIsSentWithModelPreferredLocale()
         $this->assertStringContainsString('esm',
             app('mailer')->getSymfonyTransport()->messages()[0]->toString()
         );
+
+        $mailable = new Mailable;
+        $mailable->to($recipient);
+
+        $this->assertSame($recipient->email_locale, $mailable->locale);
     }
 
     public function testLocaleIsSentWithSelectedLocaleOverridingModelPreferredLocale()