Please help me write a pytest test case for this python program.

The program works!!! please run it and write and test case which passes

def convert_roman(num):

value = (100, 90, 50, 40, 10, 9, 5, 4, 1)

symbol = ('C', 'XC','L','XL','X','IX','V','IV','I')

roman_num = ""

for i in range(len(value)):

count = int(num / value[i])

roman_num += symbol[i] * count

num -= value[i] * count

return roman_num

print(convert_roman(25))