This is an improvement request and not a bug.
You can still configure TestNG to produce JUnit compatible output.

Just want to add couple of points here for TestNG:

1. For TestNG, ${FAILED_TESTS} is giving No Tests Ran.

2. The following results page is not read by this plug-in:
${FILE, path="http://server:port/jenkins/job/<job_name>/<build_number>/"} ---> Null Pointer exception is thrown....
Please Note: Above URL is the place where the TestNG Results are displayed [We are unable to send this in the e-mail] --> presently users need to click on the link & then this data is shown!! [a bit of extra work]

--> It would be great if we could send the data (as mentioned in the attachment) in the e-mail.

This plugin only sends emails, if you want send testng results - implement this in templates and send patch to review.

The other interesting thing. I use default jelly html template but in one job it sends testng results, in other not, no ideas why (sources are same).

The FILE token does not support URLs, it only supports FILES in the workspace.

It looks like this would be easy if the testng plugin inherited from the AbstractTestResultAction. (http://javadoc.jenkins-ci.org/hudson/tasks/test/AbstractTestResultAction.html)

testng plugin needs to use the built-in way of reporting and associating test results with a build. http://javadoc.jenkins-ci.org/hudson/tasks/test/AbstractTestResultAction.html

Here is a workaround: because the Testng's ant task also generates the junit compatible reports we can use that for putting the failed tests to the emails. Just the Junit report publisher to the Jenkins project, and set the "Test report XMLs" to find the junit formatter xmls, like: "*/junitreports/.xml".
Suddenly the failing tests will start to appear in the emails.

Cheers,
Zoltan

junit defines skipped tests as failed and provides wrong FAIL status to job.

Feel free to submit a request to the testng plugin to inherit from AbstractTestResultAction. Until that happens this will remain "Won't Fix"