unittest part of test cases

import unittest


class Test(unittest.TestCase):
    def test_a(self):
        print ("a")

    def test_b(self):
        print ("b")

    def test_c(self):
        print("c")


if __name__ == '__main__':
    suite = unittest.TestSuite()
    suite.addTest(Test("test_b"))
    suite.addTest(Test("test_a"))
    with open("output", "a") as f:
        runner = unittest.TextTestRunner(f, verbosity=2)
        runner.run(suite)