[pre] blocks now preserve spaces

- Added test case
- Added English documentation

doc/BBCode.md

@@ -633,6 +633,14 @@ On Mastodon this field is used for the content warning.
   </td>
   <td>@user@domain.tld #hashtag</td>
 </tr>
+<tr>
+  <td>Additionally, [pre] blocks preserve spaces:
+    <ul>
+      <li>[pre]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Spaces[/pre]</li>
+    </ul>
+  </td>
+  <td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Spaces</td>
+</tr>
 <tr>
   <td>[nosmile] is used to disable smilies on a post by post basis<br>
     <br>

src/Content/Text/BBCode.php

@@ -1878,7 +1878,11 @@ class BBCode
 			// Remove escaping tags
 			$text = preg_replace("/\[noparse\](.*?)\[\/noparse\]/ism", '\1', $text);
 			$text = preg_replace("/\[nobb\](.*?)\[\/nobb\]/ism", '\1', $text);
-			$text = preg_replace("/\[pre\](.*?)\[\/pre\]/ism", '\1', $text);
+
+			// Additionally, [pre] tags preserve spaces
+			$text = preg_replace_callback("/\[pre\](.*?)\[\/pre\]/ism", function ($match) {
+				return str_replace(' ', ' ', $match[1]);
+			}, $text);
 
 			return $text;
 		}); // Escaped code

tests/src/Content/Text/BBCodeTest.php

@@ -241,6 +241,10 @@ class BBCodeTest extends MockedTest
 				'expectedHtml' => '[test] Space',
 				'text' => '[test] Space',
 			],
+			'task-8800-pre-spaces' => [
+				'expectedHtml' => '    Spaces',
+				'text' => '[pre]    Spaces[/pre]',
+			],
 		];
 	}