how can i write unittest for my argparser? - unit-testing

Question

This is my argparse command line interface which use to options --filter and --count.
i'm (filtering/count) a data.json file, which i convert to list python.
My question is how do I write tests for that section of the code base?
by using unittest or other libraries(modules) python of tests
def main(args):
my_parser = argparse.ArgumentParser(description='This program has to filter a list of elements containing a pattern and counts of People and Animals by counting the number of children ')
my_parser.add_argument('--filter',
metavar='Filter',
type=str,
help='filter a list of elements containing a pattern')
my_parser.add_argument('--count',
action='store_true',
help='the counts of People and Animals by counting the number of children')
args = my_parser.parse_args()
Filter= args.filter
count = args.count
data_filtered =[]
list_count = []
#Path to the data.json
path = /path/to/data.json file
# Python program to read
# json file and convert them to list python
with open(path) as f:
data = json.load(f)
if Filter:
data_filtered=[dico for dico in data for dict1 in dico['people'] for animal in dict1['animals'] if Filter in animal['name']]
if len(data_filtered) != 0:
return data_filtered
elif count:
for dico in data:
children = 0
for ele in dico['people']:
animals = len(ele['animals'])
children += 1 + animals
ele['name'] += f" [{animals}]"
dico['name'] += f" [{children}]"
list_count.append(dico)
return list_count
if __name__ == '__main__':
print(main(sys.argv[1:]))
I trayed to do this but it doesn't work for me, i want to make tests of non regression, sincerlly i have never write those kind of tests and i dont know clearly how to do it
import unittest
from collections import namedtuple
from command_line import main
class TestMycommand_line(unittest.TestCase):
args=['--filter=ry','--count']
def test_filter(self):
args = TestMycommand_line.args[0]
print(args)
res = main(args)
def test_count(self):
args = TestMycommand_line.args[1]
res = main(args)
if __name__ == '__main__':
unittest.main()