Other test frameworks
To use other test frameworks or languages with rostest, all you need to do is to provide a gtest-compatible executable in your <test> tag. gtest compatible means it takes into account the relevant command line arguments and writes suitable xml to a suitable location.
gtest uses the --gtest_output flag to specify the output location of the XML junitreport results:
junitreport XML format
gtest uses the Ant JUnit XML report format to describe the test results. This format is not well documented, though gtest has a guide:
Note that gtest does not use the full junitstructure, e.g. status is always "run", so no need to fully fill out every possible entry. A proper DTD does not seem to exist.