Special considerations for CRAN packages

Situations to use the helper skip_on_cran():

• For long-running tests you might want to skip it as CRAN packages need to run ideally in less than a minute in total.

• For valuable, well-written tests that are prone to occasional nuisance failure like the accesses a website or web API.

• For snapshot tests (default) used to monitor how various informational messages look.

For CRAN packages you can only write into the session temp directory and to clean up after yourself.

It is best to turn off any clipboard functionality in your tests.