GWTTestSuite makes builds faster, but requires JUnit 4.1
Earlier this week, I spent some time implementing GWTTestSuite to speed up my project's build process. In Hudson, the project was taking around 15 minutes to build, locally it was only taking 5 minutes for mvn test. In IDEA, I could run all the tests in under a minute. While 15 minutes isn't a long time for a build to execute, a co-worker expressed some concern:
Does Maven have to run GWT test and individual Java processes? (See target/gwtTest/*.sh) This arrangement and the overhead of JVM launches is another reason why builds take so long. As we add more GWT tests we are going to test that LinkedIn record for the slowest build ever.
After this comment, I started looking into GWTTestSuite using Olivier Modica's blog entry as a guide. It was very easy to get things working in IDEA. However, when I'd run mvn test, I'd get the following error:
Error: java.lang.ClassCastException
No line numbers. No class information. Zilch. After comparing my project's pom.xml with the one from the default gwt-maven archetype, I noticed the default used JUnit 4.1, while I had the latest-and-supposedly-greatest JUnit 4.4. Reverting to JUnit 4.1 fixed the problem. Now Hudson takes 3:15 to execute the build instead of 15 minutes.
The reason for this blog post is this doesn't seem to be documented anywhere. Hopefully other developers will find this entry when googling for this issue.
Related to making GWT faster, I also added the following line to my Application.gwt.xml file:
<set-property name="user.agent" value="safari" />
This dropped the gwt:compile time from 1 minute to 25 seconds. As explained in the documentation, you can use the "user.agent" setting to only generate one JS file for your app instead of 4. The strange thing about adding this setting was I pretty much forgot about it since everything seemed to work fine on both Safari and Firefox. When I started testing things in IE6, I started seeing a lot of JavaScript errors. After debugging for an hour or so, I realized this setting was there, removed it, and everything started working great in all browsers.
Now if I could just figure out how to use safari-only for development, but remove the line when building the WAR. Suggestions welcome.