def findMinAndMax(L):
    if not isinstance(L,list):
        raise TypeError('%s:is not a List' % L)
    if L == None or L == []:
        return None,None
    else:
        min = max = L[0]
        for num in L[1:] :
            if num < min :
                min = num
            elif num > max :
                max = num
        return min,max

if findMinAndMax([]) != (None, None):
    print('测试失败!')
elif findMinAndMax([7]) != (7, 7):
    print('测试失败!')
elif findMinAndMax([7, 1]) != (1, 7):
    print('测试失败!')
elif findMinAndMax([7, 1, 3, 9, 5]) != (1, 9):
    print('测试失败!')
else:
    print('测试成功!')

findMinAndMax(1)