Consider adding unit tests

[mcanouil]

Hi,

to avoid (or at least anticipate) issues such as #163 in the future, I recommend to use unit tests, for example with testthat (https://testthat.r-lib.org/) and setup GitHub action for R CMD checks (https://github.com/r-lib/actions/blob/v2-branch/examples/check-standard.yaml).

[dcomtois]

That would be the natural next step indeed.

Help would be much appreciated, my time is very limited and will be for a while.