support of parallelism with per test coverage data

[tom vin]

Hi,

I would like to understand a couple of thinks regarding Clover coverage tool.

As we know, surefire / failsafe has some parallel strategy for running tests, meaning - one can run his tests with a number of threads or processes. (https://maven.apache.org/surefire/maven-surefire-plugin/examples/fork-options-and-parallel-execution.html)

I saw, in the following link (https://confluence.atlassian.com/display/CLOVER/Using+Distributed+Per-test+Coverage) that in clover configuration, one have to configure the parameter "forkMode" = once, which is equals to running only one process.

Some environment background: 
we are using jenkins as a CI server, maven to build our app surefire / failsafe for running our tests. 

I wanted to know, 

can we collect coverage per test when running surefire / failsafe in parallel mode ? (threads or processes) with clover ?

Thanks,

Tom.

[Marek Parfianowicz]

You can't.

The reason is that Clover's per-test coverage feature is based on timing, not on threads. So it means that whenever given test starts and finishes, Clover calculates coverage delta - thanks to this we know what has been added to the coverage in the meantime - and this is the "per-test". Clover does not distinguish which thread generated the coverage.

[Marek Parfianowicz]

Of course you can measure global coverage with surefire's parallel mode.