UtilsSpec.groovy

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

class UtilsSpec extends Specification {

    @Unroll
    def 'flat collection of integers: #list'() {

        expect:
            Utils.flatIntegers(list) == expectedResult

        where:
            list             || expectedResult
            [[1, 2, [3]], 4] || [1, 2, 3, 4]
            [1, 2, 3]        || [1, 2, 3]
            []               || []
    }

    @Unroll
    def 'must report IAE on invalid input'() {
        when:
            Utils.flatIntegers(list)

        then:
            thrown(IllegalArgumentException)

        where:
            list << [
                    null,
                    [null],
                    [1, [2, [3, null]]],
                    [1, [2, [3]], 4, 'A']
            ]
    }
}