is.py

import unittest

def insertion_sort(iterable):
    """Given `iterable`, sort it into a list using insertion sort."""
    L = []
    iterable = iter(iterable)
    while True:
        try:
            i = next(iterable)
        except StopIteration:
            return L
        for idx, value in enumerate(L):
            if i < value:
                L.insert(idx, i)
                break
        else:
            L.append(i)


class InsertionSortTests(unittest.TestCase):

    data = [([0, 1, 2, 3], [0, 1, 2, 3]),
            ([4, 3, 2, 1], [1, 2, 3, 4]),
            ([8, 5, 7, 9], [5, 7, 8, 9])]

    def test_is(self):
        for test in self.data:
            self.assertEqual(insertion_sort(test[0]), test[1], '{0} != {1}'.format(test[0], test[1]))