Add test to cover fix from #36

test/DecodeTest.php

@@ -0,0 +1,25 @@
+<?php
+/**
+ * @see       https://github.com/zendframework/zend-mime for the canonical source repository
+ * @copyright Copyright (c) 2019 Zend Technologies USA Inc. (https://www.zend.com)
+ * @license   https://github.com/zendframework/zend-mime/blob/master/LICENSE.md New BSD License
+ */
+
+namespace ZendTest\Mime;
+
+use PHPUnit\Framework\TestCase;
+use Zend\Mail\Headers;
+use Zend\Mime\Decode;
+
+class DecodeTest extends TestCase
+{
+    public function testDecodeMessageWithoutHeaders()
+    {
+        $text = 'This is a message body';
+
+        Decode::splitMessage($text, $headers, $body);
+
+        self::assertInstanceOf(Headers::class, $headers);
+        self::assertSame($text, $body);
+    }
+}