def findMinAndMax(l):

    if l:

        a = l[0]

        b = l[0]

        for i in l:

            if a <= i:

                a = i

            if b >= i:

                b = i

        return b, a

    else:

        return None, None

if findMinAndMax([]) != (None, None):

    print('测试失败!1')

elif findMinAndMax([7]) != (7, 7):

    print('测试失败!2')

elif findMinAndMax([7, 1]) != (1, 7):

    print('测试失败!3')

elif findMinAndMax([7, 1, 3, 9, 5]) != (1, 9):

    print('测试失败!4')

else:

    print('测试成功!')