jbognar wrote:

If the JUnit publisher finds that one or more tests failed, will it
mark the build as failed, even if the build ant script itself
succeeds?

Yes.

.... unless you use the mayFailPattern attribute of the junitLogPublisher
task to tell RTC which tests are allowed to fail. Quoting the
documentation of the mayFailPattern attribute:

"A substring of a test suite class name. Any test suite class name that
contains the pattern is allowed to fail without causing the overall
build to fail. The pattern is a simple string, not a regular
expression. If not specified, any test suite failure causes the build
to fail."