In the comments of the file tests/parser/parserTests.txt (Wikimedia) it is written that the file includes context from metawiki pages. The GNU FDL and CC BY-SA 3.0 licenses do not allow inclusion of content into the GNU GPLv2.

Comment: Mediawiki does not have an official standard for wiki syntax. This means that everything that the Mediawiki software relate, acts or does is under the Copyright of Mediawiki, i.e. GPLv2. The exception may be instructions (not part of the official Mediawiki software package), due to the legal exception for educational purposes or non-profit. The copied text serves as a standard for the Mediawiki parser, so if someone wants to develop a new parser, then if he wants to be sure of the correct implementation, he must test his parse on identical data. So, these few lines play an important role in the following.