texPreview do not pass tests on all architectures

[phgrosjean]

See in your own Universe (https://yonicd.r-universe.dev/builds), the log of the different GitHub actions. It fails on Windows and macOS because it does not find tlmgr or mpm. I think your tests are designed for Linux only, but they can probably be made compatible with Windows and macOS too. On macOS, it chokes on system("tlmgr --version", intern = TRUE). So, you use this code (e.g., in test-utilities.R l. 51: if(length(system('tlmgr --version',intern = TRUE))>0) { ... }. You could use tinytex::tlmgr_version(), but the result would be the same. I think it is in the GitHub action itself where installation of tlmgr should be requested.

Looking at https://rstudio.r-universe.dev/tinytex, which passes on all OSes. You should get there what you need to passe also textPreview on Windows and macOS.