Re: [xml-dev] xml tool

Both Stylus Studio [1] and XML Spy [2] do much of this. ActiveState [3] 
has an XSLT debugger, but I haven't used it. I'm not sure exactly what 
you mean by "debug and test applications", you may want a tool like 
Eclipse or Visual Studio if you are writing the programs in Java or C#.

Personally, I use Stylus Studio, Emacs, and Eclipse every day, and the 
combination works well for me.

Jonathan

Bias alert: the company that makes Stylus Studio bought our company.

[1] http://www.stylusstudio.com/xslt_debugger.html
[2] http://www.xmlspy.com/features_xsl.html
[3] http://www.activestate.com/Products/Komodo/?_x=1
[4] http://eclipse.org/
[5] http://lab.msdn.microsoft.com/express/