They Rsync command is generally functional but contains some limitations and bugs that need to be addressed. Unfortunately, no tests for the module are present in the current Rex distribution. Basic tests should be created for the module as it currently exists and then for any existing patches and any future ones.
Current issues are:
#1356
#1355
#1315
#1290
#1075
Existing patches:
#1353
#1298
I'm willing to write tests for the issues and patches above if someone can get the ball rolling by writing basic tests for the Rsync module as it exists today.