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<h1 class="title toc-ignore">Skipping tests</h1>

Some times you have tests that you don’t want to run in certain
circumstances. This vignette describes how to skip
tests to avoid execution in undesired environments. Skipping is a
relatively advanced topic because in most cases you want all your tests
to run everywhere. The most common exceptions are:
<ul>
<li>You’re testing a web service that occasionally fails, and you
don’t want to run the tests on CRAN. Or maybe the API requires
authentication, and you can only run the tests when you’ve <a href="https://gargle.r-lib.org/articles/articles/managing-tokens-securely.html">securely
distributed</a> some secrets.</li>
<li>You’re relying on features that not all operating systems
possess, and want to make sure your code doesn’t run on a platform where
it doesn’t work. This platform tends to be Windows, since amongst other
things, it lacks full utf8 support.</li>
<li>You’re writing your tests for multiple versions of R or multiple
versions of a dependency and you want to skip when a feature isn’t
available. You generally don’t need to skip tests if a suggested package
is not installed. This is only needed in exceptional circumstances,
e.g. when a package is not available on some operating system.</li>
</ul>
<div class="sourceCode" id="cb1"><pre class="sourceCode r"><code class="sourceCode r"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>library(testthat)</code></pre></div>
<div id="basics" class="section level2">
<h2>Basics</h2>
testthat comes with a variety of helpers for the most common
situations:
<ul>
<li><code>skip_on_cran()</code> skips tests on CRAN. This is useful
for slow tests and tests that occasionally fail for reasons outside of
your control.</li>
<li><code>skip_on_os()</code> allows you to skip tests on a specific
operating system. Generally, you should strive to avoid this as much as
possible (so your code works the same on all platforms), but sometimes
it’s just not possible.</li>
<li><code>skip_on_ci()</code> skips tests on most continuous
integration platforms (e.g. GitHub Actions, Travis, Appveyor).</li>
</ul>
You can also easily implement your own using either
<code>skip_if()</code> or <code>skip_if_not()</code>, which both take an
expression that should yield a single <code>TRUE</code> or
<code>FALSE</code>.
All reporters show which tests as skipped. As of testthat 3.0.0,
ProgressReporter (used interactively) and CheckReporter (used inside of
<code>R CMD check</code>) also display a summary of skips across all
tests. It looks something like this:
<pre><code>── Skipped tests ───────────────────────────────────────────────────────
● No token (3)
● On CRAN (1)</code></pre>
You should keep an on eye this when developing interactively to make
sure that you’re not accidentally skipping the wrong things.
</div>
<div id="helpers" class="section level2">
<h2>Helpers</h2>
If you find yourself using the same
<code>skip_if()</code>/<code>skip_if_not()</code> expression across
multiple tests, it’s a good idea to create a helper function. This
function should start with <code>skip_</code> and live somewhere in your
<code>R/</code> directory.
<div class="sourceCode" id="cb3"><pre class="sourceCode r"><code class="sourceCode r"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>skip_if_Tuesday &lt;- function() {
<a href="#cb3-2" aria-hidden="true" tabindex="-1"></a> if (as.POSIXlt(Sys.Date())$wday != 2) {
<a href="#cb3-3" aria-hidden="true" tabindex="-1"></a> return(invisible(TRUE))
<a href="#cb3-4" aria-hidden="true" tabindex="-1"></a> }
<a href="#cb3-5" aria-hidden="true" tabindex="-1"></a> 
<a href="#cb3-6" aria-hidden="true" tabindex="-1"></a> skip(&quot;Not run on Tuesday&quot;)
<a href="#cb3-7" aria-hidden="true" tabindex="-1"></a>}</code></pre></div>
It’s important to test your skip helpers because it’s easy to miss if
you’re skipping more often than desired, and the test code is never run.
This is unlikely to happen locally (since you’ll see the skipped tests
in the summary), but is quite possible in continuous integration.
For that reason, it’s a good idea to add a test that you skip is
activated when you expect. skips are a special type of condition, so you
can test for their presence/absence with
<code>expect_condition()</code>. For example, imagine that you’ve
defined a custom skipper that skips tests whenever an environment
variable <code>DANGER</code> is set:
<div class="sourceCode" id="cb4"><pre class="sourceCode r"><code class="sourceCode r"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>skip_if_dangerous &lt;- function() {
<a href="#cb4-2" aria-hidden="true" tabindex="-1"></a> if (identical(Sys.getenv(&quot;DANGER&quot;), &quot;&quot;)) {
<a href="#cb4-3" aria-hidden="true" tabindex="-1"></a> return(invisible(TRUE))
<a href="#cb4-4" aria-hidden="true" tabindex="-1"></a> }
<a href="#cb4-5" aria-hidden="true" tabindex="-1"></a> 
<a href="#cb4-6" aria-hidden="true" tabindex="-1"></a> skip(&quot;Not run in dangerous enviromnents&quot;)
<a href="#cb4-7" aria-hidden="true" tabindex="-1"></a>}</code></pre></div>
Then you can use <code>expect_condition()</code> to test that it
skips tests when it should, and doesn’t skip when it shouldn’t:
<div class="sourceCode" id="cb5"><pre class="sourceCode r"><code class="sourceCode r"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>test_that(&quot;skip_if_dangerous work&quot;, {
<a href="#cb5-2" aria-hidden="true" tabindex="-1"></a> # Test that a skip happens
<a href="#cb5-3" aria-hidden="true" tabindex="-1"></a> withr::local_envvar(DANGER = &quot;yes&quot;)
<a href="#cb5-4" aria-hidden="true" tabindex="-1"></a> expect_condition(skip_if_dangerous(), class = &quot;skip&quot;) 
<a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>
<a href="#cb5-6" aria-hidden="true" tabindex="-1"></a> # Test that a skip doesn&#39;t happen
<a href="#cb5-7" aria-hidden="true" tabindex="-1"></a> withr::local_envvar(DANGER = &quot;&quot;)
<a href="#cb5-8" aria-hidden="true" tabindex="-1"></a> expect_condition(skip_if_dangerous(), NA, class = &quot;skip&quot;)
<a href="#cb5-9" aria-hidden="true" tabindex="-1"></a>})
<a href="#cb5-10" aria-hidden="true" tabindex="-1"></a>#&gt; Test passed 🥇</code></pre></div>
Testing <code>skip_if_Tuesday()</code> is harder because there’s no
way to control the skipping from the outside. That means you’d need to
“mock” its behaviour in a test, using the <a href="https://github.com/r-lib/mockery">mockery</a> or <a href="https://krlmlr.github.io/mockr/">mockr</a> packages.
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