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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
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<title>PH7 - Getting started with Autotest - Continuous
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<div class="content">
<h1>NOTE: This article was written in 2007. It is out of date.</h1>
<h1 style="text-align: center;">Getting started with Autotest -
Continuous Testing</h1>
<div id="abstract" class="Abstract">
<p class="first">Why manually run your tests, when the computer can
do it for you! <a href=
"">Autotest</a> is a
great tool to speed up test-driven development with Ruby or Ruby on
Rails. Autotest makes your coding session even more productive as
<strong>it automatically runs a subset of your test suite each time
you change a file. Autotest is smart -- it figures out which subset
to run based on the files you've changed.</strong> Think of it as
<strong><q>Continuous Testing</q></strong>.</p>
<p>Autotest source code is well-documented (<a href=
"" title=
"ZenTest documentation">rdoc</a>) but finding a high level overview
online is a little more challenging. This article will get you up
and running in no time, so that you may concentrate on writing
code. <a href="getting_started_with_autotest">Let's get
<h2 id="why_autotest">Why Autotest?</h2>
<h3 id="continuous_testing">Continuous Testing</h3>
<p>The cool thing about Autotest is that you have <strong>instant
feedback on your code</strong> (tests run within a second). Even
better, <strong>the testing happens on its own</strong> so
<strong>you no longer have to switch back and forth</strong> from
the coding context to the testing context anymore (both wise
cognitively and from a <acronym title="User Interface">UI</acronym>
perspective). This effortless and immediate feedback on your code
as well as the automated and unattended test runs are quite similar
to the characteristics of <a href=
"Martin Fowler's legendary introduction to Continuous Integration">Continuous
Integration</a> at the team level. However, continuous integration
concentrates on improving <em>integration</em> at a <em>team</em>
level while Autotest concentrates on facilitating the
<em>development</em> for a <em>single</em> developer (or
programming-pair) <em>before</em> the code gets integrated -- hence
the term <strong><dfn>Continuous Testing</dfn></strong>.</p>
<p>As this is highly visual, <strong>have a look at Nuby on Rails'
<a href="">autotest
<h3 id="quicker_test_runs">Quicker Test Runs</h3>
<p>Autotest can also provide <strong>quicker test runs</strong>
than standard convention since it intelligently monitors the
changes and only runs the tests that are impacted by these changes.
In practice this is relevant only for <q>classic</q> Rails
applications because:</p>
<li><strong>Rails conventions provide good heuristics</strong> for
Autotest to decide which tests to run when a file changes. If your
application does not stick to the classic Rails layout and naming
conventions the <q>magic</q> does not work so well anymore. In this
case, it is probably better to have Autotest <a href=
"getting_started_with_autotest#running_whole_test_suite">run your
whole test suite for all changes</a>.</li>
<li>There is value in running a <em>subset</em> of the whole test
suite <strong>only because running <q>classic</q> Rails unit tests
can be slow</strong>. This is mostly since Rails approach to unit
testing is quite unconventional and involves database access. This
approach goes against general <q>agile</q> wisdom that you should
make sure your unit tests run quickly, and do not have any
dependency for external systems. Also note that there are <a href=
well-documented ways</a> to have your Rails unit tests not depend
on the database and have them run blazing fast!</li>
<h3 id="lack_of_proper_ide">Make Up for a Lack of a Proper Ruby
<p>Autotest can come in handy if your favorite IDE has limited Ruby
support, or if you prefer a more ligthweight development
environment (text editor + terminal + Autotest): it gives you an
easy and automated way to run your tests.</p>
<h2 id="install_autotest">Install Autotest</h2>
<h3>Make Sure You Already have RubyGem Installed</h3>
<p>The easiest way to install <code>Autotest</code> is to use the
<strong>ZenTest gem</strong>. If you have no idea of what a
<dfn>gem</dfn> is, or you have not installed the RubyGem packaging
system yet, please have a look at the <a href=
"">RubyGem official website</a>. If you are
serious about Ruby development, it will be hard <em>not</em> to use
<h3 id="install_osx_ubuntu">OS X and Ubuntu</h3>
<p>On OS X or Ubuntu launch from a terminal:</p>
<pre class="command-box">
$ sudo gem install ZenTest
<h3 id="install_other_unix">Other Unix flavors</h3>
<p>For other *Nix flavors, try</p>
<pre class="command-box">
$ suPassword:<span class=
"placeholder">Type root password here</span>$ gem install ZenTest
<h2 id="run_autotest">Run autotest</h2>
<h3 id="run_rails">Ruby on Rails project</h3>
<p>Consistent with Rails principles, Autotest does not require any
configuration to run. Provided you follow classic Rails
conventions, Autotest will figure things out on its own.
<strong>Simply launch Autotest from the base directory of your Ruby
on Rails project.</strong></p>
<pre class="command-box">
$ cd <span class=
"placeholder">base directory of your Ruby on Rails project</span>$ autotest
<p>Autotest will then run all your tests (the first time), and wait
for you to modify some code:</p>
<pre class="command-box">
$ autotest
/usr/bin/ruby1.8 -I.:lib:test -rtest/unit -e "%w[test/functional/tasks_controller_test.rb test/unit/quarter_test.rb test/unit/task_test.rb].each { |f| require f }" | unit_diff -u
Loaded suite -e
Finished in 0.672928 seconds.
<strong>23 tests, 60 assertions, 0 failures, 0 errors</strong>
<p>Go ahead and <strong>modify some code in your project so that a
test fails.</strong> Save the modified file to disk and Autotest
will automatically rerun some of the tests:</p>
<pre class="command-box">
/usr/bin/ruby1.8 -I.:lib:test -rtest/unit -e "%w[test/functional/tasks_controller_test.rb test/unit/task_test.rb].each { |f| require f }" | unit_diff -u
Loaded suite -e
Finished in 0.42272 seconds.
1) Failure:
test_should_be_found(TaskTest) [<strong>./test/unit/task_test.rb:22</strong>]:
--- /tmp/diff6647.0 2006-11-15 20:46:43.000000000 -0800
+++ /tmp/diff6647.1 2006-11-15 20:46:43.000000000 -0800
@@ -1 +1 @@
-Expected result
+Actual result</strong>
<strong>4 tests, 9 assertions, 1 failures, 0 errors</strong>
<p>Note that autotest ran only a <em>subset</em> of your test suite
this time (4 tests out of 23 in my case). Also note that
<strong>Autotest is especially good in providing brief and relevant
feedback on the test failures</strong>.</p>
<p>Autotest focuses on running previous failures until you have
fixed them. So <strong>test failures are run until they have all
passed. Then the full test suite is run</strong> to ensure that
nothing else was inadvertently broken.</p>
<h3 id="run_ruby">Ruby Project</h3>
<p>In theory you would run Autotest the same way as you would for
any Ruby project -- even if it is not based on Rails:</p>
<pre class="command-box">
$ cd <span class=
"placeholder">base directory of your Ruby project</span>$ autotest
<p>In practice, Autotest might have problems finding your tests or
figuring out which tests to run when you change some code. If this
is the case, take a look at the <a href=
test detection</q></a> section.</p>
<h3 id="full_test_run">Forcing a Full Test Run and Stopping
<p><strong>If you want to force Autotest to run the <em>entire</em>
test suite</strong> <strong>hit <kbd>Ctrl - C</kbd> once</strong>
in the terminal running Autotest. Hitting <kbd>Ctrl - C</kbd> twice
will stop Autotest.</p>
<h2 id="configure_plugins">Configure Plugins</h2>
<p>Autotest also provides some cool plugins that enable you to
<strong>get feedback the way you want</strong>.</p>
<h3 id="create_dot_autotest">Create a <code>.autotest</code>
<p><strong>You configure plugins by creating a
<code>.autotest</code> file in your project base
directory</strong>. You can also provide a default configuration
for all your projects by creating a <code>.autotest</code> file in
your home directory (when present, project configuration files
override user default configuration file).</p>
<p><strong>You enable a plugin by adding a line requiring the
plugin in the <code>.autotest</code> file</strong>. For instance,
to enable the <q>Growl</q> plugin, you would add the following
<pre class="source-code-box">
require 'autotest/growl'
<p>Below you will find a description of the most popular plugins
and how to enable them.</p>
<h3 id="red_green_plugin">Red / Green Plugin</h3>
<p>The <q>Red / Green</q> plugin provides color to
<code>Autotest</code> messages in the terminal window. As expected,
output is green if all the tests pass, red if some test fails.
Having red / green visual output makes it easier for one to scan
the output and quickly determine whether everything is OK or
something went wrong.</p>
<p>Visually, the <q>Red /Green</q> plugin turns</p>
<pre class="command-box">
200 tests, 520 assertions, 0 failures, 0 errors
<pre class="command-box" style="color: green;">
200 tests, 520 assertions, 0 failures, 0 errors
<pre class="command-box" style="color: red;">
5 tests, 20 assertions, 1 failures, 0 errors
<p>To enable the <q>Red / Green</q> plugin add the following line
to your <code>.autotest</code> file:</p>
<pre class="source-code-box">
require 'autotest/redgreen'
<h3 id="desktop_notification_plugins">Desktop Notification
<p>You might not even have to look at <code>the Autotest</code>
terminal output to figure out the result of a test run.
<strong>Several plugins provide desktop notification messages
capabilities</strong>. In this way you can run Autotest in the
background and see popup messages when something fails.</p>
<h4 id="growl_plugin">Growl Plugin (OS X)</h4>
<p><a href="">Growl</a> is a popular desktop
notification system for OSX. If you are developing on a Mac, enable
the Growl plugin by adding</p>
<pre class="source-code-box">
require 'autotest/growl'
<p>to your <code>.autotest</code> file. Note that for this plugin
to work, you not only need to install <a href=""
title="Growl website">Growl</a> <strong>but also its command line
interface: <a href=
<h4 id="snarl_plugin">Snarl Plugin (Windows)</h4>
<p><a href="">Snarl</a> is a notification
system for Windows largely inspired by Growl. Autotest will use it
if you enable the Snarl plugin in your <code>.autotest</code>
<pre class="source-code-box">
require 'autotest/snarl'
<h4 id="kde_notify_plugin">KDE Notify Plugin (Linux)</h4>
<p>If you are running Linux and use KDE as your desktop
environment, you will get desktop notification by adding to your
<code>.autotest</code> file:</p>
<pre class="source-code-box">
require 'autotest/kdenotify'
<h4 id="gnome_notify_plugin">Gnome Notify plugin (Linux)</h4>
<p>If you are running Linux and use Gnome as your desktop
environment, unfortunately there is no official plugin for desktop
notification. You can still get desktop notifications by adding the
following code snipet in your <code>.autotest</code> file:</p>
<pre class="source-code-box">
module Autotest::GnomeNotify
# Time notification will be displayed before disappearing automatically
ERROR_STOCK_ICON = "gtk-dialog-error"
SUCCESS_STOCK_ICON = "gtk-dialog-info"
# Convenience method to send an error notification message
# [stock_icon] Stock icon name of icon to display
# [title] Notification message title
# [message] Core message for the notification
def self.notify stock_icon, title, message
options = "-t #{EXPIRATION_IN_SECONDS * 1000} -i #{stock_icon}"
system "notify-send #{options} '#{title}' '#{message}'"
Autotest.add_hook :red do |at|
notify ERROR_STOCK_ICON, "Tests failed", "#{at.files_to_test.size} tests failed"
Autotest.add_hook :green do |at|
notify SUCCESS_STOCK_ICON, "All tests passed, good job!", ""
<p>For this to work <strong>you need to have <a href=
installed on your system and a program named
<code>notify-send</code> in your <code>PATH</code></strong>. For
most Linux distributions this simply means that you should install
the <code>libnotify-bin</code> package. If you are running Ubuntu,
<pre class="command-box">
sudo apt-get install libnotify-bin
<h3 id="pretty_plugin">Pretty Plugin</h3>
<p>If you are running Autotest on a Mac you can enable the
<q>pretty</q> plugin to <strong>visualize your Autotest status
history</strong> as a sequence of red and green squares:</p>
<p class="figure"><img alt="Autotest Pretty Plugin Screenshot" src=
"" /></p>
<p>Of course a green square indicates passing tests while a red
square signals some test failures. If you want to get a feel of
what a session is like with this plugin enabled, ZenSpider has a
<a href=
title="ZenSpider pretty plugin video">nice video</a> demonstrating
the pretty plugin in action.</p>
<p>To enable this plugin <strong>you will need to install <a href=
"" title=
"Ruby Cocoa documentation">RubyCocoa</a></strong> and add the
folowing line to your <code>.autotest</code> file:</p>
<pre class="source-code-box">
require 'autotest/pretty'
<h3 id="html_report_plugin">HTML Report Plugin</h3>
<p>The <q>HTML report</q> plugin <strong>publishes most recent
Autotest statuses as a web page</strong> under
<code>~/Sites/autotest.html</code>. You can then point a browser to
this page and see something like:</p>
<div class="sample-box">
<div style="COLOR:green">Sat Feb 03 14:34:09 PST 2007: 0</div>
<div style="COLOR:red">Sat Feb 03 14:33:50 PST 2007: 1</div>
<div style="COLOR:green">Sat Feb 03 14:33:45 PST 2007: 0</div>
<div style="COLOR:red">Sat Feb 03 14:33:29 PST 2007: 4</div>
<div style="COLOR:green">Sat Feb 03 14:33:19 PST 2007: 0</div>
<p>Of course the content of the web page is updated while you work.
Note that <strong>you need to have an an existing
<code>~/Sites</code> directory</strong> <em>before</em> you enable
the plugin with the following line:</p>
<pre class="source-code-box">
require 'autotest/html_report'
<h3 id="menu_plugin">Menu Plugin</h3>
<p>Remember that, by default, hitting <code>Ctrl - C</code> once
will force Autotest to run the entire test suite, and hitting
<code>Ctrl - C</code> twice will stop Autotest? The <q>menu</q>
plugin changes this behavior: each time you hit <code>Ctrl -
C</code> it will explicitly ask you whether you want to quit,
restart or just keep going.</p>
<pre class="command-box">
c: continue q: quit r: restart menu&gt;
<p>Enable the menu plugin by adding the following line to your
<code>.autotest</code> file.</p>
<pre class="source-code-box">
require 'autotest/menu'
<h3 id="timestamp_plugin">Timestamp Plugin</h3>
<p>While Autotest waits for you to save a file, the timestamp
plugin prints a message with the current time. Messages look
<pre class="command-box">
# waiting... Sat Feb 03 15:56:23 EST 2007
<p>To enable the timestamp plugin add the following to your
<code>.autotest</code> file:</p>
<pre class="source-code-box">
require 'autotest/timestamp'
<h3>Getting More Information</h3>
<p>Your Autotest install comes with a sample <code>.autotest</code>
file listing all available plugins. It is named
<code>example_dot_autotest.rb</code>. You will find it in the gems
install directory. Most likely this directory will look like:</p>
on OS X.</li>
<li><code>/usr/lib/ruby/gems/1.8/gems/ZenTest-3.4.3/</code> on
other Unix platforms</li>
<p>Interesting plugins that are not distributed with Autotest can
also be found within <a href=
autotest pending patches</a>. The <a href=
"" title=
"RSpec project website">RSpec</a> patches you will find there will
be of particular interest to those of you that enjoy <a href=
"" title=
"Official Behavior Driven Development website">behavior-driven
<h2 id="troubleshoot_test_detection">Troubleshooting Autotest Test
<p>Whether Autotest does not work out of the box for you or its
magics eludes you, it is always good to get some understanding of
the heuristics that Autotest uses to figure which test(s) to
<h3 id="rails_heuristics">Heuristics for Rails</h3>
<p>Autotest automatically discovers Ruby on Rails projects by
checking for a <code>config/environment.rb</code> file. If there is
one, Autotest will base its logic on standard Rails file mappings
and conventions.</p>
<p>If for some reason you want to force Ruby on Rails mode you can
always launch Autotest it with the <code>-rails</code> option:</p>
<pre class="command-box">
$ autotest -rails
<p>A <em>simplified</em> version of Autotest heuristics in this
mode would be:</p>
<li>When changing a test file, only this file is run (e.g.
<code>test/unit/foo_test.rb</code> &rarr;
<li>When changing a model file, only associated unit test file is
run (e.g. <code>app/models/foo.rb</code> &rarr;
<li>When changing a controller file, associated functional test
file is run (e.g. <code>app/controllers/foo_controller.rb</code>
&rarr; <code>test/functional/foo_controller_test.rb</code>).</li>
<li>When changing a fixture file, associated unit test and
functional test are run (e.g. <code>app/fixtures/foos.yml</code>
&rarr; <code>test/unit/foo_test.rb</code> +
<li>When changing a helper file, associated functional test file is
run (e.g. <code>app/helpers/foo_helper.rb</code> &rarr;
<li>When changing <code>application_helper.rb</code> file all
functional test files are run (e.g.
<code>application_helper.rb</code> &rarr;
<li>When changing a file under the <code>config</code> directory,
all tests are run.</li>
<p>You've got the idea. Actual heuristics are a little more complex
and also handle the concept of <code>view</code> and
<code>controller</code> tests. <strong>For a more thourough
understanding have look at the <code>rails_autotest.rb</code>
file</strong> in ZenTest gem install directory.</p>
<p>In case these heuristics do not play well with your own
conventions, do not give up yet: <strong>you can always configure
Autotest to <a href=
"getting_started_with_autotest#running_whole_test_suite">run the
whole test suite for all changes</a></strong>.</p>
<h3 id="ruby_heuristics">Heuristics for Non Rails Projects</h3>
<p>For non Rails project, Autotest uses a simple naming scheme to
map implementation files to test files:</p>
<li>Test files must be stored in the <code>test</code>
<li>Implementation files must be stored in the <code>lib</code>
<li>Test files names must start with <code>test_</code></li>
<li>Test class names must start with <code>Test</code></li>
<li>Test files corresponding to a specific implementation file must
be named <code>test_*<span class="placeholder">name of
implementation file</span>.rb</code></li>
<p>If you can live with these conventions, Autotest will work
out-of-the-box for you. If these conventions are not your cup of
tea and you have your own, the next paragraph explains how to
configure Autotest so that it runs the whole test suite each time
you save a file.</p>
<h3 id="running_whole_test_suite">Running the Whole Test Suite for
All Changes</h3>
<p>If for some reason Autotest heuristics do not work for you, you
can customize them in your <code>.autotest</code> file with a
little bit of work.</p>
<p>For instance, if your entire test suite runs quickly (as it
should), you can easily configure Autotest to run the whole test
suite for any change by adding the following code to your
<code>.autotest</code> file:</p>
<pre class="command-box">
# Override autotest default magic deciding which test to run when
# a file is changed : enable more flexible naming conventions
# trading some of the efficiency: we rerun all the tests each time.
class Autotest
def test_files_for(filename)
return Dir["test/**/*.rb"]
<p>Autotest provides an easy and effortless way to run your tests:
just save a file. This is a great way to get quick feedback on your
code and avoid any context switch. Autotest automated test runs are
also extremelly valuable if your favorite IDE has poor Ruby
support, or if you prefer a more ligthweight development
environment (text editor + terminal + Autotest).</p>
<p>Autotest also tries hard to be smart on deciding which tests to
<li>It only runs the tests affected by your latest code
<li>When some tests fail, Autotest focuses on running previous
failures until you have fixed them. Once they pass, the full test
suite is run to ensure that nothing else was inadvertently
<p>On deciding which tests to run, Autotest <q>magic</q> works out
of the box if your application follows classic Ruby on Rails
conventions. If this is not your cup of tea, it is extremely easy
to customize Autotest to fit your conventions.</p>
<p>Via its plugins Autotest also offers a lot of interesting
feedback options, from terminal output to html publishing to
desktop notifications. The pretty plugin offers a highly visual
representation of your test runs history, which could be useful
when teaching Test Driven Development (green, red, green, red,
<p>On the flip side, It is important to note that Autotest does not
fit all developement styles: Some developers like better control on
which tests they are running. While working on a piece of code,
they will typically focuss on a few tests (which they know they
could have broken), and then run the whole test suite just before
committing. Autotest emulates this as well as it can with his focus
on running previous failures; but ultimately a human will always
have a better intuition, especially if your project does not follow
classic Rails conventions.</p>
<p>In all cases, it is worth spending some time playing with
Autotest and experiment with its innovative, lightweight and
effortless approach to test runs, what I have been calling
<q>continuous testing</q>.</p>
<p class="Copyright">&copy; Copyright Philippe Hanrigou, all rights
<p class="License">This work is licensed under a <a rel="license"
href="">Creative Commons
Attribution 2.5 License</a>.</p>
<p class="License">Used and distributed with permission from
Philippe Hanrigou.</p>
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