I just recently saw a discussion on gitter, where jglick mentioned that the junit task returns a hudson.tasks.junit.TestResultSummary.

This is a very cool feature and I bet many people like to use it, but I couldn't find it anywhere in the official documentation.

Jesse Glick @jglick Aug. 30 23:00
@sshepel you need to use the return value from the junit step, as above

Serhii Shepel @sshepel Aug. 30 23:01
But ATM currentBuild.rawBuild.getAction(AbstractTestResultAction.class) returns summary for all mvn test calls...
hm I didn't know that junit has return value
interesting
so, does this means that smth like this should work: def platformTestResults = junit allowEmptyResults: true, testResults: '*/target/surefire-reports/.xml'?

Jesse Glick @jglick Aug. 30 23:33
@sshepel yes

Serhii Shepel @sshepel 00:08
Ok, thanks @jglick will check that tomorrow

Serhii Shepel @sshepel 00:33
@jglick hm, decided to do a quick test, and got failure... What kind of value junit step shout return?
I thought that it should be hudson.tasks.junit.TestResultAction, am I wrong?
oh, strange it returns hudson.tasks.junit.TestResultSummary
then how can I get failureDiffString

Jesse Glick @jglick 02:16
.failCount as previously mentioned

Serhii Shepel @sshepel 10:32
failCount will return Gets the total number of failed tests. whereas failureDiffString returns Gets the diff string of failures... Anyway I can live without it Once again, thanks a lot @jglick