Add tests for `recursive_unicode` function #3045

Job	Run time
gatekeeper	3s
changes	4s
env	1s
documentation / build	14s
application_tester / run (windows-latest)	3m 53s
application_tester_draft / run (ubuntu-latest)	3m 54s
coverage_draft / generate and upload	3m 37s
application_tester / run (macos-latest)	3m 3s
guitest / run (ubuntu-latest)	1m 4s
guitest_draft / run (windows-latest)	2m 11s
guitest / run (macos-latest)	1m 29s
pytest / run (windows-latest)	7m 27s
mac / build	7m 53s
pytest / run (macos-latest)	3m 54s
scripttest_draft / run	1m 0s
ubuntu / build	8m 51s
windows / build	4m 34s
	53m 12s

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