---
title: "R Can Use Your Help: Testing R Before Release"
author: "Tomas Kalibera, Luke Tierney, Kurt Hornik"
date: 2021-04-28
categories: ["External Contributions"]
tags: ["testing", "bugs", "bugzilla"]
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(collapse = TRUE)
```

If you use R you may have wondered if there are ways you can contribute to
making R better. This is another post on how you might help ([Reviewing Bug
Reports](https://developer.r-project.org/Blog/public/2019/10/09/r-can-use-your-help-reviewing-bug-reports/index.html)
was the first).

This post is about helping with testing of pre-release versions of R.

Maintaining and improving R unavoidably comes with introducing regressions,
that is breaking things which worked before.  This also happens when
external software changes its behavior (OS, compilers, libraries). 
Regressions that cause the R test suite to fail are found and fixed quickly. 
Regressions that cause CRAN packages to fail are typically found soon as
well when those packages passed their tests before the regression was
introduced, yet there is some risk of overlooking these problems as there
are always some failing packages (about 50 packages out of over 17,000
currently result in ERROR or WARNING on Linux, more on other platforms, as
shown [here](https://cran.r-project.org/web/checks/check_summary.html)).

The biggest risk of overlooking regressions is in things that are not
covered by automated tests.  To allow us to improve quality of released R
versions, we could use your help with testing R. 

Planned R releases are announced via [R-announce mailing
list](https://stat.ethz.ch/pipermail/r-announce/) and detailed schedules are
at on the [R developer](https://developer.r-project.org) website.  Now is a
good time as R 4.1 is to be released soon: feature freeze happens May 4,
code freeze May 11, the release is scheduled for May 18. In order to allow
fixing the discovered issues, they would have to be reported as early as
possible.

If you would like to help, here are some things you can test.  If you find
any regressions, please report them (see [Reporting
Bugs](https://www.r-project.org/bugs.html) via [R bug
tracker](https://bugs.r-project.org) or [R-devel mailing
list](https://stat.ethz.ch/mailman/listinfo/r-devel)).  If you find bugs
that are not regressions (bugs in new features or bugs that existed in
earlier releases), please still report them.

## On all platforms

Please be careful not to damage your existing R installation.  Only use a
fresh package library for the tests.  When possible, it may be a good idea
to use virtual machines for the testing.

Test things that are interactive (installation, front-ends, interactive R
packages, manual installation).  Test things that interact with external
libraries.

If you use R and have your own programs and data, your own workflows, your
special ways of installing or setting up R, please test that. Unusual
settings are most likely to trigger regressions, and this way you may most
directly benefit from getting things fixed. If you are maintaining an R
package and have tests that are not run automatically, hence also during
CRAN checks, please run them now.

## On Windows

You can use a virtual machine, such as virtualbox, for the testing (there
are some [free VMs](https://developer.microsoft.com/en-us/microsoft-edge/tools/vms/) for
time-limited testing). Using a virtual machine avoids the problem of
damaging an existing R installation and allows to test installation from
scratch, including dependent software.

Pre-release versions of R can be installed from
[here](https://cran.r-project.org/bin/windows/base/rpatched.html).  Some
areas where issues are most likely/have been seen in the past:

- Test the Windows installer. Try also with different non-default options.
  There have been some improvements in the installer in 4.1, so potentially
  also regressions.

- Test interactive R packages, particularly those using some graphical
  interface or external software, including Tcl/Tk, Java, etc.

- Test with non-ASCII/non-European characters.  This is especially useful if
  you normally work with data with such characters.  Please only look for
  regressions: there are a number of known limitations of the encoding
  support on Windows, which should be overcome once there is a stable
  release with UTF-8 support as native encoding.  Still, all characters
  supported by the native encoding should work, even when it is an encoding
  for a non-European language.

- Test with unusual characters in file names (spaces, etc).  Please
  only look for regressions as such characters are discouraged, so ideally
  if you are using such names with R already, test on the same data.

- Test RTerm, the command-line front-end for R. There has been a significant
  change of the implementation of line editing for 4.1 fixing issues with
  non-European characters.  Potential regressions could also impact use with
  ASCII and European characters, even though less likely.

- Test RGui, the graphical front-end for R.

## On macOS

Please see [R for macOS Developers](https://mac.r-project.org/) for binaries
for the alpha version of 4.1 and more information.  Particularly interesting
would be tests on Big Sur, which comes with stricter security checks by
default, and on M1, both Intel builds running with emulation and the native
64-bit ARM builds.

- Test installation and the macOS GUI frontend. Ideally test with
  non-default settings.  Test the documentation in [R Installation and
  Administration](https://cran.r-project.org/doc/manuals/r-patched/R-admin.html),
  check whether it is sufficiently up-to-date and matches experience
  on your system.

- Test with non-European/non-ASCII characters. On macOS, R uses UTF-8 as the
  native encoding by default, so all characters should work. There have been
  some improvements in 4.1 to Unicode support, so possibly there may be
  regressions visible on macOS as well.

- Test building R from source, following the instructions in [R Installation
  and Administration](https://cran.r-project.org/doc/manuals/r-patched/R-admin.html). 
  This is especially useful on clean/new systems when one has to deal with
  OS settings and installing dependent software.

## On Linux

- Test building R from source on your favourite distribution. Particularly
  useful may be checks on less common distributions and with non-default
  build/`configure` options.

- Test interactive R packages, ideally with your own data, especially useful
  are checks that involve external software.

- If you use forking support in parallel package (`mclapply`, etc) and have
  your own applications/data/clusters built on that API, test it with the
  new version.

## On Solaris

If you use R on Solaris, please test anything similar to the above.  This
may be the least tested R platform at this point.  Solaris may be prone to
encoding issues in R when working with supplementary Unicode characters (a
bit like Windows, but on Solaris one might test different code paths). 

## Helping regularly

If you are interested in helping R this way repeatedly, it may be useful to
create a check-list, possibly also with some code and data, so that you can
easily repeat the tests before the next R release. This type of help would
be useful also for minor R releases.
