Does Coverage plugins need that unit tests run beforehand

Question

I couldnt find this info anywhere. In order to get code coverage calculated using a plugin (like Jococo, Cobertura..etc) Do I need to run all the unit tests before? These look like relevant tasks, But still I think Code coverage should not be dependent on running unit tests before hand, unless coverage plugin really relies on the Junit

Answer 1

You do not need to run tests beforehand. The coverage tool instruments the code (if required), runs the tests (or your main) and then reports the stats back to you.

Having said that, if your code relies of fancy reflection/bytecode manipulation, it may be a good idea to run tests beforehand, just to make sure that failures reported during the coverage scan the the instrumentation's fault and not "real" test failures.