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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'

If you’re on Mac OS X then you also 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"


You can use Steam by itself as well as with Cucumber. You can find an example for a Cucumber setup in examples/cucumber/env.rb.

Steam is widely compatible with Webrat – many actions are implemented and take the same or very similar parameters as their Webrat equivalent. You even might be able to use the default webrat_steps.rb that ships with Cucumber, but his file is meant as an example and might be out of date.


You can find a demo application here:

Comparsion to others

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 stack 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
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