Add PdfSignedMessage and its serializer

Added a new class, PdfSignedMessage, to handle received signed PDF messages. Also, added a serializer for this class, PdfSignedMessageSerializer, for use with messaging. Furthermore, comment documentation has been added to RequestPdfSignMessage and its serializer for better clarity. Updated unit tests are also included.

src/Bundle/ChillDocStoreBundle/Tests/Service/Signature/Driver/BaseSigner/PdfSignedMessageSerializerTest.php

@@ -0,0 +1,63 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * Chill is a software for social workers
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Chill\DocStoreBundle\Tests\Service\Signature\Driver\BaseSigner;
+
+use Chill\DocStoreBundle\Service\Signature\Driver\BaseSigner\PdfSignedMessage;
+use Chill\DocStoreBundle\Service\Signature\Driver\BaseSigner\PdfSignedMessageSerializer;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Messenger\Envelope;
+
+/**
+ * @internal
+ *
+ * @coversNothing
+ */
+class PdfSignedMessageSerializerTest extends TestCase
+{
+    public function testDecode(): void
+    {
+        $asString = <<<'JSON'
+            {"signatureId": 0, "content": "dGVzdAo="}
+            JSON;
+
+        $actual = $this->buildSerializer()->decode(['body' => $asString]);
+
+        self::assertInstanceOf(Envelope::class, $actual);
+        $message = $actual->getMessage();
+        self::assertInstanceOf(PdfSignedMessage::class, $message);
+        self::assertEquals("test\n", $message->content);
+        self::assertEquals(0, $message->signatureId);
+    }
+
+    public function testEncode(): void
+    {
+        $envelope = new Envelope(
+            new PdfSignedMessage(0, "test\n")
+        );
+
+        $actual = $this->buildSerializer()->encode($envelope);
+
+        self::assertIsArray($actual);
+        self::assertArrayHasKey('body', $actual);
+        self::assertArrayHasKey('headers', $actual);
+        self::assertEquals([], $actual['headers']);
+
+        self::assertEquals(<<<'JSON'
+                {"signatureId":0,"content":"dGVzdAo="}
+                JSON, $actual['body']);
+    }
+
+    private function buildSerializer(): PdfSignedMessageSerializer
+    {
+        return new PdfSignedMessageSerializer();
+    }
+}