Merge pull request #69 from aitap/detritus

"Found detritus in the temp directory"

code_issues.qmd

@@ -301,6 +301,29 @@ Packages can write per default to `tempdir()`, or any other temporary/cache dire
 
 <!-- tbd: add section about R_user_dir() --> 
 
+---------------------------------------
+
+# Leaving Files in the Temporary Directory
+
+## Problem
+
+Some of your code that runs during ` R CMD check ` creates files in the temporary directory specified by the environment variable `TMPDIR` and doesn't remove them afterwards. As a result, ` R CMD check ` gives your package a NOTE complaining about the "detritus in the temp directory".
+
+## Solution
+
+If you use `tempfile()`/`tempdir()` as the default destination for functions called in your examples or tests, `unlink()` the resulting files as part of the test. In the `\examples{}` section of your help files, clean-up actions can be wrapped in `\dontshow{}` for aesthetic reasons. If you launch a browser, 'Calibre', 'Python' code or other software, and it creates temporary files, find out where they are and remove them once the code is done with them.
+
+### Details
+
+::: {.callout-note title="CRAN NOTE" icon=false}
+Check: for detritus in the temp directory, Result: NOTE\
+&emsp; Found the following files/directories:\
+&emsp;&emsp;  ‘this\_is\_detritus382e569a7712’
+:::
+
+The code responsible for the detritus may include your own tests and examples creating files under `tempdir()`, child processes, or 'Python' code launched using 'reticulate'. For example, R packages that use the 'tensorflow' 'Python' package [find and remove temporary files created by its auto-gradient feature](https://github.com/cran/vetiver/blob/35b24768cf0e84fab96610e001bba377dc777953/tests/testthat/setup.R#L13).
+
+A package that uses the 'testthat' test suite will benefit from [the self-cleaning functions `withr::local_tempfile()` and `withr::local_tempdir()`](https://r-pkgs.org/testing-design.html#sec-tests-files-where-write) to work with temporary files. Even without 'testthat', the 'withr' package has no external strong dependencies and can be used independently.
 
 ---------------------------------------