TimeoutExceptionProof.groovy

import org.spockframework.runtime.SpockAssertionError
import spock.lang.Specification
import spock.util.concurrent.PollingConditions


class TimeoutExceptionProof extends Specification {

    final def pollingConditions = new PollingConditions(timeout: 10, initialDelay: 1)

    def "why does it fail"() {
        when:
        def foo = "bar"

        then:
        def loopCount = 0
        try {
            pollingConditions.eventually {
                loopCount += 1
                Thread.sleep(2500)
                assert false == true
            }
        } catch (IllegalArgumentException iae) {
            throw new SpockAssertionError("Illegal Arg exception: loop count $loopCount", iae)
        }

    }
}

Noting that the longer that delay within the eventually is, the sooner in the loop count it's going to tank.