Installing "Additional" Packages During Tests

[brodie gaslam]

Sorry, previous e-mail got pre-maturely sent due to fat finger...
My package unitizer[1] has recently gained the following type of error:
     Warning in install.packages(pkg, repos = NULL, type = "src") :     'lib = "/home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages"' is not writable
     Error in install.packages(pkg, repos = NULL, type = "src") : 
     unable to install packages

While I did recently update the package to resolve the RNGversion issue, this problem seems unrelated as some of the CRAN machines produce it, and some don't, on the same package version.
The tests install some dummy packages with `install.packages`, and this has worked for a long time, but no longer, presumably due to changes in permissions of the test running daemon.  The packages are removed on.exit.  The packages are used for integration tests as unitizer is a package-testing-package and it is useful to be able to test functionality that includes use on actual packages that change.

Should I expect this to be the new normal, where I will be henceforth disallowed from installing packages temporarily?  Will there be an acceptable workaround (e.g. setting up a temporary library in a tempdir and try to `install.packages` into that; I admit I have no familiarity with this other than the vague awareness maybe this could be done)?
FWIW, perhaps an indication that this is something I shouldn't be doing came up earlier in the year when I had to resort to temporarily unsetting "R_TESTS" as per [2].
Thanks in advance for any input.
Best,
Brodie.


[1]: https://cran.r-project.org/web/checks/check_results_unitizer.html[2]: https://github.com/r-lib/testthat/issues/144
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