The Quiz Extension has a lot of long lines, that should be wrapped, split and reformatted to improve the code readability.
The Quiz extension was created by a volunteer and is currently installed on several WMF projects, such as Wikiversity.
Install mediawiki locally. It is easiest (often) to use vagrant for this. Quiz is not available as a role in vagrant, so follow these directions to manually add lines to LocalSettings.php in vagrant, and include the line
You can test that the extension is working by adding a sample quiz to your test wiki in wikitext. The quiz syntax is well documented here.
You can find the quiz extension in the vagrant repository by navigating to mediawiki/extensions/Quiz. If you haven't already, you will need to set up git, gerrit, and git-review, and install a gerrit hook to begin submitting commits to the Quiz extension.