Disabling parallel test execution when running test with coverage in Intellij

What sbt task does intellij IDEA 14 use to run scala tests with coverage? I'm test my spark code and need to prevent them running in parallel.

I've added the following to my build.sbt file and it prevents tests running in parallel when they aren't generating coverage reports:

parallelExecution in Test := false

However this has no effect when running with coverage. I tried using something similar, but with ScctTest instead of Test, but sbt couldn't resolve it.

So, what coverage plugin does intellij use, and how can I disable parallel test execution when running tests with coverage? Running sbt tasks doesn't show anything containing the word coverage. I haven't enabled the Emma plugin in intellij - only the default Coverage one is enabled and it has no information.