[Notifier] Check for maximum number of buttons in slack action block

src/Symfony/Component/Notifier/Bridge/Slack/Block/SlackActionsBlock.php

@@ -26,6 +26,10 @@ final class SlackActionsBlock extends AbstractSlackBlock
      */
     public function button(string $text, string $url, string $style = null): self
     {
+        if (25 === \count($this->options['elements'] ?? [])) {
+            throw new \LogicException('Maximum number of buttons should not exceed 25.');
+        }
+
         $element = [
             'type' => 'button',
             'text' => [

src/Symfony/Component/Notifier/Bridge/Slack/CHANGELOG.md

@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+5.3.0
+-----
+
+ * Check for maximum number of buttons in Slack action block
+
 5.2.0
 -----
 

src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackActionsBlockTest.php

@@ -0,0 +1,62 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Notifier\Bridge\Slack\Tests\Block;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Notifier\Bridge\Slack\Block\SlackActionsBlock;
+
+final class SlackActionsBlockTest extends TestCase
+{
+    public function testCanBeInstantiated(): void
+    {
+        $actions = new SlackActionsBlock();
+        $actions->button('first button text', 'https://example.org')
+            ->button('second button text', 'https://example.org/slack', 'danger')
+        ;
+
+        $this->assertSame([
+            'type' => 'actions',
+            'elements' => [
+                [
+                    'type' => 'button',
+                    'text' => [
+                        'type' => 'plain_text',
+                        'text' => 'first button text',
+                    ],
+                    'url' => 'https://example.org',
+                ],
+                [
+                    'type' => 'button',
+                    'text' => [
+                        'type' => 'plain_text',
+                        'text' => 'second button text',
+                    ],
+                    'url' => 'https://example.org/slack',
+                    'style' => 'danger',
+                ],
+            ],
+        ], $actions->toArray());
+    }
+
+    public function testThrowsWhenFieldsLimitReached(): void
+    {
+        $section = new SlackActionsBlock();
+        for ($i = 0; $i < 25; ++$i) {
+            $section->button($i, $i);
+        }
+
+        $this->expectException(\LogicException::class);
+        $this->expectExceptionMessage('Maximum number of buttons should not exceed 25.');
+
+        $section->button('fail', 'fail');
+    }
+}