Selenium Broken by Firefox Upgrade on Ubuntu

I use Webrat and Selenium to automate browser testing. There can be an problem with Firefox 3 on Ubuntu that requires configuring Selenium to point the Firefox binary directly.

 
Webrat.configure do |config|
 config.mode = :selenium
 config.selenium_browser_key = '*firefox3 /usr/lib/firefox-3.0.10/firefox'
end 

The problem is when Firefox is upgraded the path to the binary will change. That causes an error at the beginning of the test run.

16:10:07.104 WARN - POST /selenium-server/driver/ HTTP/1.1
java.lang.RuntimeException: java.lang.NullPointerException
   at org.openqa.selenium.server.browserlaunchers.BrowserLauncherFactory.createBrowserLauncher(BrowserLauncherFactory.java:145)
   at org.openqa.selenium.server.browserlaunchers.BrowserLauncherFactory.getBrowserLauncher(BrowserLauncherFactory.java:85)
   at org.openqa.selenium.server.BrowserSessionFactory.createNewRemoteSession(BrowserSessionFactory.java:318)
   at org.openqa.selenium.server.BrowserSessionFactory.getNewBrowserSession(BrowserSessionFactory.java:118)
   at org.openqa.selenium.server.BrowserSessionFactory.getNewBrowserSession(BrowserSessionFactory.java:81)
   at org.openqa.selenium.server.SeleniumDriverResourceHandler.getNewBrowserSession(SeleniumDriverResourceHandler.java:658)
   at org.openqa.selenium.server.SeleniumDriverResourceHandler.doCommand(SeleniumDriverResourceHandler.java:392)
   at org.openqa.selenium.server.SeleniumDriverResourceHandler.handleCommandRequest(SeleniumDriverResourceHandler.java:368)
   at org.openqa.selenium.server.SeleniumDriverResourceHandler.handle(SeleniumDriverResourceHandler.java:129)
   at org.mortbay.http.HttpContext.handle(HttpContext.java:1530)
   at org.mortbay.http.HttpContext.handle(HttpContext.java:1482)
   at org.mortbay.http.HttpServer.service(HttpServer.java:909)
   at org.mortbay.http.HttpConnection.service(HttpConnection.java:816)
   at org.mortbay.http.HttpConnection.handleNext(HttpConnection.java:982)
   at org.mortbay.http.HttpConnection.handle(HttpConnection.java:833)
   at org.mortbay.http.SocketListener.handleConnection(SocketListener.java:244)
   at org.mortbay.util.ThreadedServer.handle(ThreadedServer.java:357)
   at org.mortbay.util.ThreadPool$PoolThread.run(ThreadPool.java:534)
Caused by: java.lang.NullPointerException
   at org.openqa.selenium.server.browserlaunchers.FirefoxChromeLauncher.<init>(FirefoxChromeLauncher.java:62)
   at org.openqa.selenium.server.browserlaunchers.Firefox3Launcher.<init>(Firefox3Launcher.java:30)
   at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
   at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
   at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
   at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
   at org.openqa.selenium.server.browserlaunchers.BrowserLauncherFactory.createBrowserLauncher(BrowserLauncherFactory.java:137)
   ... 17 more 

Then each test will fail with a Selenium::CommandError: Selenium::CommandError. The fix is simple, just update the path to the Firefox binary. Hopefully this will save someone some time.