To echo
To trust code, it needs to be reviewed.
If the code is reviewed, and the build system is sane, [..]
I deduce from your response that the binary tests committed in systemd were not reviewed
neither by co-maintainers nor by downstream package maintainers.
I understand that the build system used by systemd makes it much less probable that some
binary blob used in a test obfuscates something that could be used for other purposes
outside the test; still, wouldn't you agree it would be a good practice to make sure
everyone is able to review everything in the source code repository?