Allow aborting sending mails via Mail.send event. (#17635)

* Allow aborting sending mails via Mail.send event.

* Add quick entry to developer changelog.

* add test

1 files changed, 58 insertions, 1 deletions

diff --git a/tests/PHPUnit/Integration/MailTest.php b/tests/PHPUnit/Integration/MailTest.php
index 8b64543fc6..f93a94279a 100644
--- a/tests/PHPUnit/Integration/MailTest.php
+++ b/tests/PHPUnit/Integration/MailTest.php
@@ -9,9 +9,27 @@
 namespace Piwik\Tests\Integration;
 
 use Piwik\Mail;
+use Piwik\Piwik;
+use Piwik\Tests\Framework\TestCase\UnitTestCase;
 
-class MailTest extends \PHPUnit\Framework\TestCase
+class MailTest extends UnitTestCase
 {
+    /**
+     * @var Mail[]
+     */
+    public $sentMails = [];
+
+    public function setUp(): void
+    {
+        parent::setUp();
+        $this->sentMails = [];
+    }
+
+    public function tearDown(): void
+    {
+        $this->sentMails = [];
+        parent::tearDown();
+    }
 
     public function getEmailFilenames()
     {
@@ -29,4 +47,43 @@ class MailTest extends \PHPUnit\Framework\TestCase
         $mail = new Mail();
         $this->assertEquals($expected, $mail->sanitiseString($raw));
     }
+
+    public function test_abortSendingMail()
+    {
+        $mail = new Mail();
+        $result = $mail->send();
+
+        $this->assertTrue($result);
+        $this->assertCount(1, $this->sentMails);
+
+        Piwik::addAction('Mail.send', function (&$mail) { $mail = null; });
+
+        $mail2 = new Mail();
+        $result = $mail2->send();
+
+        $this->assertNull($result);
+        $this->assertCount(1, $this->sentMails);
+    }
+
+    protected function provideContainerConfig()
+    {
+        $mockTransport = new class($this) extends Mail\Transport {
+            private $testCase;
+
+            public function __construct(MailTest $mailTest)
+            {
+                $this->testCase = $mailTest;
+            }
+
+            public function send(Mail $mail)
+            {
+                $this->testCase->sentMails[] = $mail;
+                return true;
+            }
+        };
+
+        return [
+            Mail\Transport::class => $mockTransport,
+        ];
+    }
 }