[TASK] Add unit test to cover stdWrap_append

Releases: master
Resolves: #76846
Change-Id: Ia269a9d72b90235b0ee181604e868ea2c859dfec
Reviewed-on: https://review.typo3.org/48733


Tested-by: Bamboo TYPO3com <info@typo3.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>