Fix #215: pre tags with attrs not being parsed (#238)

Author: stbneb

src/Converter/PreformattedConverter.php

@@ -11,7 +11,9 @@ class PreformattedConverter implements ConverterInterface
     public function convert(ElementInterface $element): string
     {
         $preContent = \html_entity_decode($element->getChildrenAsString());
-        $preContent = \str_replace(['<pre>', '</pre>'], '', $preContent);
+        $preContent = \preg_replace('/<pre\b[^>]*>/', '', $preContent);
+        \assert($preContent !== null);
+        $preContent = \str_replace('</pre>', '', $preContent);
 
         /*
          * Checking for the code tag.

tests/HtmlConverterTest.php

@@ -300,6 +300,7 @@ public function testPreformat(): void
         $this->assertHtmlGivesMarkdown("<pre>\n\n\n</pre>", "```\n\n\n\n```");
         $this->assertHtmlGivesMarkdown("<pre>\n</pre><pre>\n</pre>", "```\n\n```\n\n```\n\n```");
         $this->assertHtmlGivesMarkdown("<pre>one\ntwo\r\nthree</pre>\n<p>line</p>", "```\none\ntwo\nthree\n```\n\nline");
+        $this->assertHtmlGivesMarkdown("<pre class='some-class'>test with attributes</pre>", "```\ntest with attributes\n```");
     }
 
     public function testBlockquotes(): void