When drilling down into unit tests execution measures, you will eventually reach the unit test class level:
This The Source tab simply displays the source code of your the unit test classfile:
This The Tests tab displays the result of the unit tests belonging to the unit tests test class.
In case the test failed or was in of a failure or an error, the reason of the issue can be viewed.is displayed:
Since Sonar 3.5, it is also possible to display the files covered by a specific unit test:
This The Violations tab displays the violations on the unit tests: