Headless integration testing w/ HtmlUnit: enables testing JavaScript-driven web sites
JavaScript Ruby Java
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Steam is a headless integration testing tool driving HtmlUnit to enable testing JavaScript-driven web sites. In that it is similar to Culerity which drives Celerity (which also drives HtmlUnit). See below for a comparsion.


Steam currently has the following dependencies:

  • Working Java Runtime
  • HtmlUnit (jar files)
  • RJB and Locator gems

Installing Steam as as a gem will automatically install the required RJB and Locator gems:

$ gem install steam

To install HtmlUnit you can download it from Sourceforge.

You then need to add HtmlUnit to your Java classpath. The following ways should both work:

# anywhere during startup, e.g. in features/support/env.rb
ENV['CLASSPATH'] = Dir["path/to/your/htmlunit/*.jar"].join(':')

# after steam has been added to the load path, e.g. in features/support/env.rb
Steam.config[:html_unit][:java_path] = 'path/to/your/htmlunit'

Since some Mac OS X 10.6 update removed the Java header files that are necessary to compile RJB one also needs to install Java for Mac OS X 10.6 Update 3 Developer Package

Also, if you are on Mac OS X, use `sudo` and get an error saying that “JAVA_HOME is not set” then you need to export the JAVA_HOME variable for RJB. See here for two solutions: Installing RJB on Mac OS X. The visudo way worked for us. Don’t forget to add yourself to the sudoers file, though.


You should not need to configure anything. If you do need though have a look at Steam.config

E.g. in order to tweak the Java load params you can

Steam.config[:java_load_params] = "-Xmx2048M"

If you want to test your application through Cucumber features then you need to setup your Cucumber environment and steps accordingly. You can find an example for a Cucumber setup here: env.rb.

Steam is widely compatible with Webrat – many actions are implemented and take the same or very similar parameters as their Webrat equivalent. As a starting point you might want to copy the file webrat_compatible_steps.rb over to your features/step_definitions directory.


To test your application it needs to be available through http, so usually you want to start a test server:

script/server -e test # Rails < 3.0.0
rails server  -e test # Rails >= 3.0.0
rackup        -E test # etc.

If you have Cucumber set up you should now be able to run your features through Steam in a separate terminal (unless you’ve detached your server):

cucumber features/*.feature

Be sure to restart the server if you make changes to your application. During development it might be useful to enable class reloading on the test server. You also might want to consider having separate environments for development with Cucumber/Steam and running the full test suite, e.g. on CI (where you keep class reloading disabled for faster test runs).


You can find a demo application here: http://github.com/clemens/steam-demo

Comparsion to others

Steam’s advantages over plain Webrat:

  • Steam can test your Javascript and CSS, ’nuff said

Plain Webrat’s advantages over Steam:

  • It’s still a little bit easier to set up. All full-stack integration testing tools still require you to manage more than one process (i.e. you have to start a server for the application). Webrat can run your tests, the “browser” (session) and application all in the same process, just like classic Rails integration tests.

Steam’s advantages over Culerity/Celerity:

  • runs in Ruby MRI and does not require an entire JRuby environment.
  • Steam can have the HtmlUnit browser running in the same process as your tests, thus making the whole thing less complex and hard to debug
  • Steam does not build on Celerity which is a quite heavy-weight Ruby wrapper around HtmlUnit adding a lot of unnecessary code
  • Steam uses Locator

Culerity/Celerity’s advantages over Steam:

  • RJB can’t resolve the mismatch of Ruby vs Java threads which makes fancy setups impossible to solve
  • Celerity implements a lot of stuff, maybe it contains something you need (e.g. maybe you want to test pop-down windows opening in the background?)
  • Steam still is in its infancy


Kudos to Alexander Lang for writing Culerity which pioneered full-stack AJAX-enabled integration testing in Rails.



  • explain requirement to start/restart a test server
  • explain log levels