Cannot run Spock spec by right-clicking class in editor if file also contains abstract base spec

import spock.lang.*

abstract class BaseSpec extends Specification {
  def x = { println 'base field initializer' }()

  def setupSpec() { println 'base setupSpec()' }
  def cleanupSpec() { println 'base cleanupSpec()' }

  def setup() { println 'base setup()' }
  def cleanup() { println 'base cleanup()' }

  def baseSpecMethod() { setup: println 'base spec method' }
}

class DerivedSpec extends BaseSpec {
  def y = { println 'derived field initializer' }()

  def setupSpec() { println 'derived setupSpec()' }
  def cleanupSpec() { println 'derived cleanupSpec()' }

  def setup() { println 'derived setup()' }
  def cleanup() { println 'derived cleanup()' }

  def derivedSpecMethod() { setup: println 'derived spec method' }
}