I'd be great if our sonar instance at sonarqube.com would report test coverage.
Docs are here: http://docs.sonarqube.org/display/PLUG/Code+Coverage+by+Unit+Tests+for+Java+Project

Just to file similar instruments (findbug and error-prone): we also can have a look at Eclipse Che experience in this question: https://github.com/eclipse/che/wiki/Development-Workflow#validate-your-changes