coalesce.py

import unittest

def coalesce(*args):
    for a in args:
        if a is not None:
            return a
    else:
        raise ValueError("No values found to return")




class TestCoalesce(unittest.TestCase):
    def test_empty(self):
        with self.assertRaises(ValueError):
            coalesce()

    def test_all_failed(self):
        with self.assertRaises(ValueError):
            coalesce(None, None)

    def test_find_valid(self):
        self.assertEqual(coalesce(None, 42, None, "asdfa", None), 42)
        self.assertEqual(coalesce(1, 2, 3), 1)
        self.assertEqual(coalesce(None, 0, "last value"), 0)


unittest.main()