BankSpec.groovy

import spock.lang.Specification
import spock.lang.Unroll

import java.time.*

@Unroll
class BankSpec extends Specification {
    final ZoneId warsaw = ZoneId.of("Europe/Warsaw")

    def 'should calculate downtime also in DST'() {
        given:
            LocalDate date = LocalDate.of(2015, Month.OCTOBER, day)
            ZonedDateTime from = ZonedDateTime.of(date, LocalTime.of(2, 30), warsaw)
            ZonedDateTime to = ZonedDateTime.of(date, LocalTime.of(3, 30), warsaw)
        when:
            Duration duration = Duration.between(from, to)
        then:
            duration == Duration.ofHours(expectedHours)
        where:
            day | expectedHours
            24  | 1
            25  | 2
            26  | 1
    }
}