[R-pkg-devel] Passing CRAN check when an examples must save a file

[Duncan Murdoch]

On 26/09/2019 11:43 p.m., Zachary Flynn wrote:
> I am working on a function in a package that saves a file.  I want to write
> an example to document the function so it must save a file, but when I do,
> the automatic CRAN checks reject the package because there is a
> non-standard file saved in the directory when the second test runs (first,
> it runs a test on Windows where the check error does not occur, then on
> Linux where it does).  The relevant check output is:
> 
> * checking for non-standard things in the check directory ... NOTE
> Found the following files/directories:
>    ‘Produc.csv’
> 
> There is no file called Produc.csv anywhere in the directory (the
> error doesn't show up in the first run on Windows).
> 
> It is generated by running the example code which automatic CRAN
> testing might be doing in between running the Windows and Linux
> checks?
> 
> How do I write an example that must save a file to be an example of
> using the function without triggering this issue?

Save the file to the temporary directory, ẹ.g.

   filename <- file.path(tempdir(), "Prodục.csv")
   write.csv(something, file = filename)

You could clean up at the end of the example with

   unlink(filename)

but you shouldn't rely on this alone to prevent the error:  if you're 
writing files, you should *only* be doing it in the temporary directory.

Duncan Murdoch